INTERNATIONAL CONGRESS ON PHTHIRAPTERA
Buenos Aires, Argentina
16 - 20 October, 2006
Host: Centro de Investigaciones de Plagas e Insecticidas (CITEFA/CONICET)
Venue: Pestana Buenos Aires Hotel, Carlos Pellegrini 877, Buenos Aires, Argentina.
Each of the oral presentations have an abstract which may be viewed by clicking on the number within brackets following the title. Click on the title for a PowerPoint Presentation, if any. Use the left index of the PowerPoint to jump to images, or click on the icon on the lower left to eliminate the index. Click on the icon on the lower right for a full screen slide show.
Posters will be on display all day Thursday, October 19, with presenters in attendance from 12:00 - 13:00 and beyond if necessary. For a listing of posters presented click here.
|Monday, 16 October
|08:30 - 13:00
|09:30 - 10:00
|Welcome and opening ceremony
|10:00 - 11:00
|Symposium: Phthirapterists and Phthirapterology
Chairs: Bob Dalgleish & Steve Barker
|10:00 - 10:15
|Berlin 1975: The forgotten symposium. 
Mey, E.; Dalgleish, R. & Rékási, J.
|10:15 - 10:30
|Theresa Clay (1911-1995): Phthirapterist extraordinaire 
Dalgleish, R. & Meiners, M.
|10:30 - 10:45
|Electronic resources for studying lice. 
Smith, V.; Dalgleish, R.; Rycroft, S. & Reed, D
|10:45 - 11:00
|Psocodea in the Tree of Life Project. 
Bess, E.; Smith, V. & Johnson, K.
|11:00 - 11:30
|11:30 - 13:15
|Symposium: Faunistics and Morphology
Chairs: Ricardo Palma & Armando Cicchino
|11:30 - 12:00
|Plenary lecture: Kiwis are lousy. 
|12:00 - 12:15
|Chewing lice of Brazil: Present knowledge based on literature. 
|12:15 - 12:30
|Biodiversity of Anoplura in Argentina. 
|12:30 - 12:45
|Chewing lice on captive Parrots and Passerines in Czech Republic. 
|12:45 - 13:00
|Functional micromorphological specializations of the human head louse. 
Green, E. & Turner, M.
Welcome reception will be held in the glass-fronted foyer of the Pestana Buenos Aires Convention Centre. One The Welcome Reception is included in registration fee, including students, fellowship holders and accompanying guests.
|13:00 - 14:30
|14:30 - 17:00
|Symposium: Microorganisms Associated with Lice
Chairs: John Edman & Alejandra Perotti
|14:30 - 15:00
|Plenary lecture: Establishment and in vitro maintenance of Pediculus colonies: Key to research on microbial transmission and louse control. 
Edman, J.; Yoon, K.; Takano-Lee, M. & Clark, J.
|15:00 - 15:30
|Plenary lecture: - Lice as hosts: evolution and development of host-symbiont interaction. 
|15:30 - 15:45
|In vitro feeding and long term in vitro breeding of the human body louse P. h. humanus. 
Habedank, B.; Bartmann, T.; Schrader, G. & Schein, E.
|15:45 - 16:00
|Symbiotic bacteria associated with stomach disc of human lice Pediculus humanus and P. capitis. 
|16:00 - 16:30
|16:30 - 16:45
|Evolutionary relationships of a new lineage of Entero-bacteriacae living as an endosymbiont in Anoplura 
|16:45 - 17:00
|Molecular characterization of symbiotic bacteria isolated from columbiform bird lice. 
|Tuesday, 17 October
|09:00 - 09:30
|Keynote lecture: Head louse infestations worldwide. 
Mumcuoglu, K. Y.
|09:30 - 11:00
|Round Table discussion: Criteria to evaluate the quality of efficacy trials in the topical treatment of head lice.
Chairs: Robert van der Stichele & Kosta Y. Mumcuoglu
|11:00 - 11:30
|11:30 - 15:00
|Symposium: Epidemiology of Human Lice
Chairs: Hilde Lapeere & Alda González
|11:30 - 12:00
|Plenary lecture: Epidemiology of human lice. 
|12:00 - 12:30
|Plenary lecture: Pediculosis: Yesterday and today. 
González, A. & de Villalobos, C.
|12:30 - 12:45
|Individual treatments in the context of an effective strategy for the prevention of Pediculosis capitis in the UK. 
Ibarra, J.; Wickenden, C.; Fry, F.; Jenner, M. & Franks, A.
|12:45 - 13:00
|Epidemiology of Pediculosis capitis in elementary schools of Buenos Aires, Argentina. 
Vassena, C.; Toloza, A.; Gonzalez Audino, P.; Mougabure Cueto, G .; Zerba, E. & Picollo, M.
|13:00 - 14:30
|14:30 - 14:45
|Diagnosis of head louse infestation by plastic detection comb: An epidemiological study in Turkey. 
Balcioglu, C.; Burgess, I.; Limoncu, E.; Sahin, T.; Ozbel, Y.; Bilaç, C.; Ozgur, K. & Larsen K.
|14:45 - 15:00
|Physicians' answers to a questionnaire regarding head louse infestations in Turkey. 
Taylan-Ozkan, A; Coskun, O.; Mungan, M.; Babur, C.; Ertek, M. & Mumcuoglu, K.
|15:00 - 18:00
|Symposium: Prophylaxis & control of lice
Chairs: Terri Meinking & Eduardo Zerba
|15:00 - 15:30
|Plenary lecture:Evolution of head lice control in Argentina after permethrin resistance. 
|15:30 - 15:45
|Control of pediculosis: Status of resistance and monitoring. 
|15:45 - 16:00
|Role of esterases in enhanced detoxication of pyrethoids in P. h. capitis from Buenos Aires. 
González Audino, P.; Barrios, S.; Picollo, M. & Zerba, E
|16:00 - 16:30
|16:30 - 16:45
|Physiochemical parameters related with the bioactivity among essential oil components against permethrin-resistant P. h. capitis. 
Toloza, A..; Mougabure Cueto, G.; Zygadlo, J.; Zerba, E. & Picollo, M
|16:45 - 17:00
|The 7 cis- or trans-coumaryl permethrate esterases as a possible biochemical marker of pyrethroid resistance in P. h. capitis. 
Orihuela, P.; Picollo, M.; Zerba, E. & Masuh, H.
|17:00 - 17:15
|Pyrethroid resistance in eggs of P. h. capitis from Argentina. 
Mougabure-Cueto, G.; Zerba, E. & Picollo, M.
|17:15 - 17:30
|Preliminary studies of oral and topical ivermectin in the treatment of head lice. 
Burkhart, C. G.
|17:30 - 17:45
|The bug busting wet combing method to detect and eradicate head lice. 
Ibarra, J.; Fry, F.; Wickenden, C. & Smith, J
|17:45 - 18:00
|Pediculicides in the bathroom cabinet. 
|Wednesday, 18 October - COUNTRY DAY
|Visit an authentic Argentinean farm in crop and cattle production, located 87 kilometers from Buenos Aires city (1 hour of trip approximately).
|Depart by bus from Hotel Pestana
|Reception in the typical building of the gaucho (we call it “rancho de adobe”).
Empanadas (meat pies), wine and juice.
Visits to the different places: museum, bakery, etc.
|Grill: sausages, short rib of grill, chicken, etc...
Salad: Provenzal potatoes, mixed and carrot and egg.
Drinks: red and white wine, cola drink, water and sparkling water.
|Cooked "mate" (boiled water) and sweet cakes with quince jelly
|Leave for hotel
|Thursday, 19 October
|09:00 - 09:30
|Keynote lecture: What is a good randomised control trial of a pediculicide? 
Barker, S.; Casey, C. & Burgess, I.
|09:30 - 12:00
|Symposium: Medical and Veterinary Aspects of Louse Infestations.
Chairs: Craig G. Burkhart & Craig N. Burkhart.
|09:30 - 10:00
|Plenary lecture: Clinical aspects of lice infestation. 
Craig N. Burkhart
|10:00 - 10:15
|An effective non-chemical treatment for head lice: A lot of hot air. 
|10:15 - 10:30
|Water - is it the “Achilles heel” of sucking lice? 
|10:30 - 10:45
|Susceptibility of human head lice to entomopathogenic nematodes. 
Bess, E.Doucet, M.; Miranda, M. & Bertolotti, M.
|10:45 - 11:00
|Resistance to insect growth regulator insecticides in Australian sheep louse (Bovicola ovis Schrank) populations. 
James, P.; Levot, G.; Sales, N.; Hook, S. & Camp, A
|11:00 - 11:30
|11:30 - 11:45
|The relationship between louse numbers and pruritis in sheep: How good is rubbing as an indicator of infestation? 
James, P. & Bartholomaeous, F.
|11:45 - 12:00
|The controlled crossing on Eucalyptus species as a potential technique to improve the pediculicidal activity of essential oils. 
Lucia, A.; Toloza, A.; Masuh, H.; Gonzalez-Audino, P.; Zerba, E. & Picollo, M.
|12:00 - 13:00
|13:00 - 14:30
|14:30 - 17:00
|Symposium: : Behaviour, Ecology & Epidemiology of Animal Lice
Chairs: Dale H. Clayton, D. & Noah K. Whiteman
|14:30 - 15:00
|Plenary lecture: The role of body size in host specificity: Reciprocal transfer experiments with feather lice. 
Clayton, D. & Bush, S.
|15:00 - 15:30
|Plenary lecture:Galápagos hawks and their chewing lice: A model system for studying host-parasite ecology. 
Whiteman, N. & Parker, P
|15:30 - 16:00
|16:00 - 16:15
|On the sexual practices of animal lice. 
|16:15 - 16:30
|Indirect measures of sexual selection in avian lice. 
Rózsa, L. Harnos, A.
|16:30 - 16:45
|- Host defense facilitates the coexistence of competing lice species. 
Bush, S.; Malenke, J. & Clayton, D
|16:45 - 17:00
|Comparative transmission dynamics of ecological replicates: Experiments with columbiform body and wing lice. 
Harbison, C.; Bush, S.; Malenke, J. & Clayton, D.
|17:00 - 17:15
|Evolution of cryptic coloration in host-specific lice. 
Kim, D.; Reed, M.; Bush, S. & Clayton
|17:15 - 17:30
|Local adaptation differentiates haplotypes of a feather-feeding louse: Incipient speciation? 
Malenke, J.; Johnson, K. & Clayton, D
A special dinner will be served consisting of Argentinian food and wine. You will be invited to participate in a Tango-Show. One ticket to the Congress Dinner is included in full-registration fee, premium students, and accompanying guests.
It is not included in student or award registration fees.
|Friday, 20 October
|09:00 - 13:00
|Symposium: Systematics, Population Genetics & Evolution
Chairs: Vince Smith & Kevin Johnson
|09:00 - 09:15
|The diversification of lice: Origins. 
Johnson, K.; Yoshizawa, K. & Smith, V.
|09:15 - 09:30
|The diversification of lice: Age 
Smith, V.; Ford, T.; Johnson, K.; Johnson, P.; Yoshizawa, K. & Page, R.
|09:30 - 09:45
|The diversification of lice: Phylogeny. 
Smith, V. & Johnson, K.
|09:45 - 10:00
|The diversification of lice: Specialization 
Johnson, K. & Smith, V.
|10:00 - 10:15
|The fossilization and discovery of Megamenopon rasnitsyni, the first fossil louse. 
Lutz, H.; Wappler, T. & Dalgleish, R.
|10:15 - 10:30
|Mitochondrial genomics of lice and their relatives. 
Cameron, S.; Covacin,C.; Johnson, K. & Whiting, M
|10:30 - 10:45
|Micro- and macroevolutionary perspectives into the cophylogenetic history of toucans and their chewing lice. 
Weckstein, J.; Bates, J. & Aleixo, A.
|10:45 - 11:00
|Louse population genetics as a tool for understanding the individual and population histories of their hosts. 
Whiteman, N.; Kimball, R. & Parker, P
|11:00 - 11:30
|11:30 - 11:45
|Phylogeny, cophylogeny, and molecular rate comparisons of Fahrenholzia sucking lice and their Heteromyid hosts. 
Light, J. & Hafner, M
|11:45 - 12:00
|Host-parasite associations, geography and population subdivision in Polyplax serrata and wood mice of genus Apodemus. 
Stefka, J.; Hypsa, V.; Fricová & Stanko, M
|12:00 - 12:15
|Taxonomic problem of Gyropus parvus parasite of Ctenomys. 
Martino, N.; Romero, M.; Sánchez Sánchez, G. & Castro, D.
|12:15 - 12:30
|Pair of lice lost: Parasites as markers of primate evolutionary history. 
Reed, D.; Light, J. & Allen, J.
|12:30 - 12:45
|Parasitic lice as markers of human evolutionary history. 
Reed, D.; Light, J.; Allen, J.; Carter, T. & Long, L.
|12:45 - 13:00
|Genetic analyses of human lice: Implications for human evolution. 
|13:00 - 14:30
|14:30 - 16:00
|Round Table discussion:The body louse genome project.
Chairs: John Clark & Peter Pittendrigh
|14:30 - 16:00
|Closing discussion: ICP4 and closing ceremony
Berlin 1975: The Forgotten Symposium.
Eberhard Mey1, Robert C. Dalgleish2 & József Rékási3
1 Museum of Natural History of the Thuringian State Museum Heidecksburg, Schloßbezirk 1, D-07407 Rudolstadt, Germany. email@example.com
2 10601-G Tierrasanta Blvd., #110, San Diego, CA, 92124 U.S.A. firstname.lastname@example.org
3 Pannonhalma, Var 2., H-9090 Hungary.
The organizers of The Second International Congress on Phthiraptera, Brisbane, Australia, 2002, considered the Symposium on the Control of Lice and Louse-borne Diseases, Washington, D.C., U.S.A., 1972, as the first International Symposium. They were not aware of the International Symposium held in Berlin, Germany, November, 1975. As participants in the 1975 symposium we wish to address this oversight and summarize its content, for it was a significant event in advancing knowledge on the systematics and biology of lice. Thus technically today we are attending the Fourth International Symposium on Phthiraptera.
Theresa Clay (1911 - 1995) Phthirapterist Extraordinaire.
Robert C. Dalgleish1 & Mary L. Meiners2
110601-G Tierrasanta Blvd., #110, San Diego, CA, U.S.A. email@example.com
2Department of Psychology, Miramar College, San Diego, CA, U.S.A.
"Louse taxonomy is a fools game, and the fools are winning!" so concluded the last piece of advice I received from Theresa Clay just before she retired after 37 years of taxonomic research on lice at the British Museum Natural History. My hero, my mentor, was urging me to pursue the taxonomy of another group of insects. I resolved to discover what lead her to express such despair.
Theresa attended St. Paul's Girls School, London, then the University of Edinburgh, earning a BSc. in Zoology in 1934. She was awarded a DSc. by the same institution in 1955.
Her association with the British Museum (Natural History) began in 1938 as a volunteer (Unofficial Worker), assisting with the relocation and curation of specimens during the period of World War II. In 1949 she received a temporary appointment then a full-time staff position in 1952 as Senior Scientific Officer. Her interest in lice predates her employment at the Museum and her publications are restricted to these parasitic insects. In 1970 she was appointed Deputy Keeper, Department of Entomology. She retired from the Museum in 1975. There was no published acknowledgement of her retirement, Festschrift, or detailed obituary.
With the exception of her professional publications Theresa Clay did not leave a body of information from which one can define the person. My personal knowledge of her, while limited, does however, help trace her life and guides me in selecting interpretations of her actions. What does remain are the diaries of Richard Meinertzhagen and a few pieces of correspondence and official documents in the archives of the Museum. Meinertzhagen knew her from infancy, they had a close personal and professional relationship which included the last fifty years of his life. Within his diaries Theresa Clay is invariably referred to as "Tess". The diaries also provide some insight into the development of Theresa's interest in lice, especially the chewing lice of birds.
In the introduction to their checklist, Price, Hellenthal and Palma (2003:5) record Clay as being the author or coauthor of 217 species or subspecies of chewing lice, of which they consider 208 as being valid. These authors "followed closely the conclusions reached by Hopkins and Clay...(1952) and her "taxonomic philosophy." Thus their consideration of 96% of Clay's species as being valid is not surprising, nor is it matched by any worker who described chewing lice from both birds and mammals. As with Price and Palma, I consider myself as closely allied with the species concept of Clay, however, I believe she was overly cautious in defining generic limits.
Clay, in large part due to her relationship with Meinertzhagen, had an impact well beyond her scientific publications. While her scientific integrity has not been questioned she cannot be entirely removed from Meinertzhagen's mischief.
Electronic resources for studying lice.
Vincent S. Smith1, Robert C. Dalgleish2, Simon Rycroft3, and David L. Reed4
1 The Natural History Museum, London, UK.
2 10601-G Tierrasanta Blvd., #110, San Diego, CA, U.S.A. firstname.lastname@example.org
3 Univ of Glasgow, Scotland, UK.
4 Florida Museum of Natural History, Univ of Florida, Gainesville, FL, U.S.A.
The World Wide Web has become an essential medium for disseminating the products of taxonomic and systematic research. Data sets, publications, images, checklists and keys can electronically transcend geographic barriers at the click of a button, minimizing the delay that traditionally besets taxonomic research. In an effort to build up a virtual network of taxonomists and resources supporting research on Phthiraptera, Bob Dalgleish established Phthiraptera.org - a website devoted to sharing and advancing knowledge about lice. This site includes checklists, classifications, biographies and an on-line forum for discussion. Arguably Phthiraptera.org's greatest asset is its extensive bibliography and searchable index of over 8,500 articles published on lice, of which nearly three thousand can be downloaded as full text PDF's. As a repository for digital images of lice, Vince Smith and Simon Rycroft developed SID - a Specimen Image Database that can be used as a reference image collection for named specimens, and a resource for comparative morphological research. SID (http://sid.zoology.gla.ac.uk) presently holds almost eight thousand images for approximately 450 louse taxa. Each image is accompanied by fully searchable annotation, and can be browsed, searched or downloaded. The database is entirely web based and open so that any registered users can submit, annotate or label images on-line. Finally, as part of the BioCorder project (www.biocorder.org), efforts are underway to provide integrated on-line access to the collective works of Price et al's 2003 “World Checklist of Chewing Lice”, and Durden and Musser's 1993 “Sucking Lice of the World”, both of which have been databased by the Vince Smith, and integrated with other major mammal and bird checklists. In addition, work is ongoing to integrate these lists with Lienhard and Smithers 2002 “World Catalogue and Bibliography of Psocoptera”, with the eventual aim of providing a freely available and web editable access point to all taxonomic and checklist associations on Psocodea, that would be maintained by the community, for the community.
Psocodea in the Tree of Life Project.
Emilie Bess1, Vincent S. Smith2, Charles Lienhard3 & Kevin P. Johnson4
1 Univ of Illinois at Urbana-Champaign, Dept of Entomology, USA.
2 The Natural History Museum, London, UK.
3 Museum of Natural History, Geneva, Switzerland.
4 Illinois Natural History Survey, Champaign, Illinois, USA.
The Tree of Life web project is a collaborative Internet database with the goal of functioning as a central clearinghouse for taxonomic data, images, and literature. Taxonomic information is presented as a series of interconnected phylogenetic trees that allow the user to view information about organisms of any taxonomic rank. Our contribution to this ambitious project includes up-to-date phylogenies of Phthiraptera and “Psocoptera” (Psocodea), along with illustrations, comprehensive bibliographies, and discussion of morphology, geographic distribution, ecology, and systematic relationships among the taxa. By adding data on approximately 4500 species of “Psocoptera” and 5000 species of Phthiraptera, we are nearly doubling the number of taxa in the Tree of Life database. We hope that this contribution will encourage entomologists to become involved in this wide-reaching project.
Kiwis are lousy.
Ricardo L. Palma
Museum of New Zealand Te Papa Tongarewa, New Zealand.
Kiwis (Aves: Apterygiformes: Apterygidae: Apteryx) are flightless, nocturnal birds exclusive to New Zealand, with 6 species and subspecies currently recognised as valid. They are ancient elements of the fauna believed to have descended from a flying ancestor, which may have been already in New Zealand when its landmass separated from Gondwanaland about 80 mya, or which may have arrived at a later date. In pre-human times kiwis were distributed in all forested areas of New Zealand, covering over 80% of the country. However, their distribution has been greatly reduced due to human activities during the last 1000 years, to the extent that, at present, they mostly survive in a few, relatively isolated areas. Kiwi lice belong to two genera, one in the family Philopteridae: Rallicola (four species), and the other in the Menoponidae: Apterygon (four species). The four species of Rallicola are morphologically uniform and sufficiently different from all other species in the genus to justify placing them in their own subgenus: Aptericola. Both Apterygon and Aptericola (together with Huiacola) are the only supraspecific louse taxa endemic to New Zealand. Harrison described the first species of kiwi lice in 1915, but some of them have not 'survived' subsequent revisions. Both Clay in the 1960's and Tandan in the 1970's increased the number of valid kiwi lice species to six; Palma in 1991 and Palma & Price in 2002 completed the current total of eight known species. Further detail morphological studies, complemented with molecular analyses, may allow future identification and description of more louse species, especially from small and geographically isolated kiwi populations. Following the publication of the first descriptions of kiwi lice belonging to the genus Rallicola, it was believed that kiwis' closest relatives were rails (family Rallidae). However, this theory was later dismissed because ornithological evidence indicated a closer relationship with ratites (in particular emus and cassowaries). Kiwis are very uniform in their morphology and therefore have proven difficult to identify to species by traditional methods; they are, in taxonomic terms, an excellent example of cryptic taxa. A study of the geographical distribution of kiwis and their host-louse associations shows a great degree of host-louse specificity, to the extent that one southern host population can only be distinguished by the identity of its louse fauna and not from its ornithological features. A kiwi population isolated on a small northern island was believed to have been introduced to that island by humans at the beginning of the 20th Century, until the discovery of its unique louse species showed that kiwis had been living on the island at least since pre-European times. Another small, morphologically cryptic kiwi population was recognised as a possible different taxon after the identification of its lice in 1979. Subsequent analysis of its DNA and detailed studies of its external morphology confirmed its uniqueness, until it was described and published as a new species in December 2003.
Chewing lice of Brazil: Present knowledge based on literature.
Michel P. Valim
Dept of Parasitology, Universidade Federal de Minas Gerais, Brazil. email@example.com
Financial support by CNPq/Brazil
A survey on the available literature was made to ascertain the knowledge of chewing lice fauna parasitizing birds in Brazil. The figures given below are the sum of the number of louse species actually recorded from birds in Brazil plus others that could potentially be living on Brazilian birds. The bird orders that occur in Brazil with their respective numbers of families, genera and species, plus the number of recorded bird species with chewing louse are: Struthioniformes (1/1/1/1), Tinamiformes (1/5/23/18), Sphenisciformes (1/3/4/4), Podicipediformes (1/5/5/4), Procellariiformes (4/18/40/37), Pelecaniformes (6/7/14/14), Ciconiiformes (3/25/33/29), Phoenicopteriformes (1/2/4/3), Cathartiformes (1/3/5/5) Anseriformes (2/15/26/20), Falconiformes (3/31/66/46), Galliformes (2/8/26/9), Opisthocomiformes (1/1/1/1), Gruiformes (6/18/39/21), Charadriiformes (13/38/79/73), Columbiformes (1/8/22/17), Psittaciformes (1/24/83/47), Cuculiformes (1/8/19/8), Strigiformes (2/11/23/13), Caprimulgiformes (3/11/30/4), Apodiformes (2/40/97/19), Trogoniformes (1/2/9/6), Coraciiformes (2/5/9/6), Galbuliformes (2/13/41/10), Piciformes (3/15/78/26), Passeriformes (31/357/985/177). Five orders, Sphenisciformes, Pelecaniformes, Cathartiformes, Struthioniformes and Opisthocomiformes, have 100% of their species with records of chewing lice in Brazil. Eight orders have more than 70% of their species with records of chewing lice, a knowledge level regarded here as good: Tinamiformes (78.26%), Podicipediformes (80%), Procellariiformes (92.50%), Ciconiiformes (87.88%), Phoenicopteriformes (75%), Anseriformes (76.92%), Charadriiformes (92.41%) and Columbiformes (77.27%). On the other hand, a poor level of knowledge (30%) is found in four orders: Caprimulgiformes (13.33%), Apodiformes (19.59%), Galbuliformes (24.39%), and Passeriformes (17.97%). it is very unlikely that avian orders containing a high number of species, such as Caprimulgiformes and Passeriformes, will end up having such a low percentage of louse-positive host species. only 35.07% of the total number of brazilian birds has been recorded as hosts of chewing lice, with about 1,082 species of lice distributed in 130 genera and four families. these figures clearly show that it is still necessary to carry out faunal surveys to proper record all the brazilian chewing louse fauna, sound alpha taxonomy research to describe, name and publish unknown taxa.
Biodiversity of Anoplura (Phthiraptera) in Argentina.
Dolores del C. Castro
Facultad de Ciencias Naturales y Museo de La Plata, calle 64 Nº 3, Laboratorio Zoología General, CP1900, La Plata, Buenos Aires, Argentina. castrodreon@Lpsat.com
Further knowledge on biodiversity is essential if it is intended to rationally preserve and use it taking into account ecological changes, mainly, due to gross alterations in the natural habitat. The optimum geographical situation of Argentina, has helped diversity of arthropods, and Anoplura, are also included. They are significantly important as much in the economic aspect as in the sanitary point of view, causing a marked decrease in the production of domestic animals, and being well-known as pathogenic agents vectors. Around 564 world-wide known species were grouped in 51 genera and 15 families; 150 species were found in South America (26, 5%). In Argentina there are 85 species (15%), that are distributed in 22 genera (43%) and 11 families (73%). Comparing these data, the number of species known for Argentina concerning South America countries reaches 56.6%. Taking into account that 45 species have been described for South America as well as 32 for Argentina (5 more are under study), and in 11 families, Hoplopleuridae is the most widely represented, these ectoparasites are highly significant for our country. Great expectations have been focused on the study of parasitic species in wild mammals, in particular Rodentia Order, since they represent one of the most important groups within South American mastozoologic fauna. Twelve families of this mammal order were found to be in Argentina, at least 6 of them are parasitized with Anoplura. The greatest specific diversity may be obtained from new studies dealing which hosts of the Muridae family with 97 species in which 39 (40%) have one or more Anoplura. The Octodontidae family has 50 species in which 21 (42%) are parasitized with Anoplura. Studies on these rodent parasites are of vital importance since they are used as reservoirs or transmitters of pathogens; also a significant affinity between host-pathogen-ectoparasite may be observed. Data dealing with rodents as reservoirs of pathogenic microorganisms and their ectoparasites like vectors or transmitters, are scarce in Argentina, mainly in the Pampa region where more than 70% of diversity is distributed. Also endemics epidemiologists are closely related to Rodentia reservoirs and transmission (Argentine hemorrhagic fever, FHA) as well as to local transmitters of severe to lethal viruses through excreta (Hanta virus, HV). There has been an increasing interest in farming, fact that led to alterations in the natural habitat of such rodents, promoting marked changes in soil and in the edafic fauna, particularly in foretic coleopters associated with other ectoparasites among them the lice.
Chewing lice on captive Parrots (Psittaciformes) and Passerines (Passeriformes) in Czech Republic.
Dept of Biology and Wildlife Sciences, Univ of Veterinary and Pharmaceutical Sciences Brno, Czech Republic.
The aim of my study was to record the incidence of chewing lice among the most numerous captive birds in Czech Republic, and to determine the prevalence and intensity of infestation of individual species of chewing lice on captive birds. Three hundred and twenty six parrots and songbirds of 41 species from private breeders, pet shops and zoological gardens were searched for lice from 2002 to 2004. Ectoparasites were collected using the fumigation chamber method specifically adapted for captive birds. All the lice were fixed in 96% ethanol, subsequently slide-mounted as permanent slides and determined. Four species of parrots and four species of passerines were infested: Rose-ringed Parakeet (Psittacula krameri) by Echinophilopterus chapini and Neopsittaconirmus lybartota, Budgerigar (Melopsittacus undulatus) by N. gracilis, Cockatiel (Nymphicus hollandicus) by Neopsittaconirmus sp., Green-winged Macaw (Ara chloroptera) by Heteromenopon militaris, Canary (Serinus canaria) by Menacanthus eurysternus, Myrsidea serini and Brueelia cyclothorax, Zebra Finch (Taeniopygia guttata) and Lavender Waxbill (Estrilda caerulescens) by Brueelia sp. and Gouldian Finch (Chloebia gouldiae) by Menacanthus sp. Total prevalence was 3 % and 43 % for parrots (n = 265) and passerines (n = 61), respectively. The mean intensity of infestation was 17.3 and 75.9 lice per infested parrots and passerines, respectively. Five cases of heavy infestation of a Budgerigar (118 ex. of N. gracilis) and four Canaries were found. Very high infestation by the haematophagous species Menacanthus eurysternus (612 ex.) was recorded on a Canary, which had probably died in cause of a trauma. Viable populations of chewing lice can survive and breed on captive exotic birds. It is surprising that no species of chewing lice have been yet described from some of the most popular bird species kept in aviaries throughout the world (e.g. Cockatiel or Zebra Finch). I found host-specific lice, that are still described only from wild birds (E. chapini and N. lybartota from Rose-ringed Parakeet, H. militaris from Green-winged Macaw), as well as stragglers from another captive or wild birds - N. gracilis, that I found on Budgerigars, was originally described from the Yellow-collared Lovebird (Agapornis personatus), Brueelia cyclothorax from Canary was originally described from wild Sparrows (Passer spp.). This is the first record of lice of genus Brueelia on Canary. New species of chewing lice of the genus Neopsittaconirmus and Brueelia were found on Cockatiel and Zebra Finch respectively. This is the first record of chewing lice from Cockatiel. Another infestations reported here shows that these lice could be host-specific for Cockatiel or Zebra Finch as well as stragglers from another captive bird. However, the finding of nymphs indicated that they can successfully bred on captive birds.
Functional micromorphological specializations of the human head louse.
Edward D. Green1 & M. L. Turner2
1 Dept of Anatomy, Box 232, Univ of Limpopo, Medunsa 0204, South Africa. firstname.lastname@example.org
2 Electron Microscope Unit, Box 232, Univ of Limpopo, Medunsa 0204, South Africa.
Human head lice are bloodsucking obligate ectoparasites infesting human hair and require a number of bloodmeals daily. Besides fleas, they are considered to be the insects most frequently associated with humans. Pediculosis is reported in 25% of elementary school children in the United States each year. Although not known to transmit disease, their bites frequently cause irritation and scratching of the scalp and neck. As previous studies had obviously used dried specimens resulting in the inevitable morphological distortions, this study was aimed at investigating the micromorphology of freshly fixed head lice by scanning electron microscopy (SEM) in order to obtain a clearer understanding of how these lice attach to, feed and orientate on their hosts. Head lice collected from school children in Pretoria were fixed directly in 70% ethanol. After ultrasonic cleaning, the lice were routinely prepared for SEM and viewed in a Leica Stereoscan 420 scanning electron microscope at 5 to 10 kV. The head included a pair of lateral eyes, each of which were seen as a simple-lensed ommatidium, a pair of 5-segmented antennae and a single tubular haustellum. The haustellum was horse-shoe shaped forming a simple sucker, which housed hooked stylets used for penetrating the skin, thus enabling it to reach superficial bloodvessels. The distal antennal segment bore specialized sensoria including a tuft organ enclosed in each pore organ, a double plate organ and a terminal peg organ comprising 10 sensilla. Antennal segment 4 bore a pore and tuft organ. These sensoria are required for orientation on the host's head, location of prospective mates and for retreating from noxious substances. The thorax was fused with a pair of legs attached to the pro-, meso- and metathorax segments. Each joint of the leg had a scaled membranous area with a number of openings, which may represent secretory glands as found in the bedbug Cimex lectularius. Each leg terminated in a tarsal claw, which closed against a distotibial process. The tarsal apophysis carried a long curved spine, which further improved attachment. A unique branched empodium-like structure, similar to that described in the lousefly, was observed at the base of the tarsal claw. A large round spiracular opening was seen on the mesothorax, which was lined internally by honeycomb-shaped lamellae. These may act as filters for air entering the trachea. Six pairs of abdominal spiracles were embedded in the lateral protective paratergites. These spiracles were protrudant, thus enabling the louse to regulate the entrance of toxic substances such as insecticidal shampoos as reported by Burkhart, CN et al. (2000). The gonopod VIII of the female is designed to clasp the hair, whilst the long tactile setae hold the egg in position as it is cemented to the hair. These specializations would have contributed to the continued pediculosis of humans for thousands of years.
Establishment and in vitro maintenance of Pediculus colonies: key to research on microbial transmission and louse control.
John D. Edman, K. S. Yoon, M. Takano-Lee & John M. Clark
Univ of California, Davis and Univ of Massachusetts, Amherst, U.S.A.
Research on the transmission of louse-borne Rickettsia and the efficacy of or resistance to various pediculicides has been hampered by the inability to colonize and maintain field derived populations of human lice. Recently, we developed in vitro methods to colonize and maintain both head and body lice for long periods without a human host. Stirred, heparinized human blood (expired, banked blood to which infectious agents can be added) is periodically and automatically pumped from a refrigerator into a heated, stirred vessel containing many partially-submerged plastic tubes with a membrane-covered bottom and a screw cap top. Lice are attach to bundles of human hair inside the vials. Saline is automatically pumped through the blood-holding vessel to clean the system just prior to the periodic addition of new blood. All active louse stages readily feed through the membranes which consists of stretched Parafilm® reinforced with a thin layer of silicone to provide elasticity after stretching. Female lice readily mated and deposited their eggs on the hairs in the same vials used for maintaining and feeding the lice. Both permethrin susceptible and resistant head lice from several states and countries have been colonized from express-shipped eggs and maintained in this system along with a colony of body lice. For the first time, field-derived head and body lice of uniform stage and age can be used experimentally to: (1) evaluate new control methods and compare the efficacy of controversial old ones, (2) carefully document the resistance of field populations of lice from anywhere in the world, (3) explore the genetic basis of louse resistance to various pesticides and develop new molecular methods for detecting resistance, and (4) compare the ability of both resistant and susceptible head and body lice to acquire and transmit different strains and species of bacteria under controlled, yet semi-natural conditions. The rearing system is not costly and avoids ethical issues surrounding the feeding of arthropods on vertebrate hosts, especially humans. It facilitates long-needed experiments on the ability of various louse stages, geographic strains and species to acquire, maintain and transmit Rickettsia and other infectious agents. It should be adaptable to other difficult to maintain arthropods such as pubic lice, bed bugs and soft ticks.
Lice as hosts: evolution and development of host-symbiont interaction.
M. Alejandra Perotti
School of Biological Sciences, Univ of Wales Bangor, LL57 2UW, UK.
The first microscopical description of a human louse nymph was carried out by Robert Hook in 1665. It was this initial observation that showed the presence of a prominent organ present in all human lice, the 'stomach disc'. Some 250 years later, this organ was associated with obligatory symbiosis and an unknown pleiomorphic bacterium. For another ninety years numerous attempts to isolate, culture or identify the mycetomic bacterium had failed. Eventually a combination of micro dissection and fluorescence in situ hybridisation allowed us to identify the primary endosymbiont. Pediculus humanus capitis, P. h. humanus and Pthirus pubis host strictly obligate and organ-forming symbionts, Candidatus Riesa spp., representing a new bacterial lineage in the Gammaproteobacteria. Human and most animal lice also harbour a secondary endosymbiont, Wolbachia pipientis, an Alphaproteobacteria. The identification of these endosymbionts enabled us to illustrate the evolution of an extraordinary variety of unique and intricate host-endosymbiont interactions depictured in physiological and morphological adaptations, which indeed have shaped the life history traits of their lice hosts. The primary endosymbionts of human lice have evolved into one of the most complex systems with two sequential provisional, transitory or transport mycetomes, a main mycetome and a paired filial mycetome. Most likely sucking and chewing lice have evolved twice from within the book- and barklice, Psocoptera, forming together the Psocodea. The first demonstration of a mycetome and of obligatory endosymbionts in Psocoptera is of particular importance for unravelling the evolutionary history of lice. The Psocoptera endosymbionts show an evolutionary transition from a solitary to a primary mycetomic bacterium adapted to the development of their parthenogenetic hosts. It suggests that regardless of their feeding habits, barklice, booklice, and vertebrate lice share ancient symbiotic arrangements. The finding of obligatory symbiosis in the non-blood feeding Liposcelis lineage, which is most closely related to the Anoplura advocates a possible loss of the parasitic lifestyle of lice. The obligate symbionts are entirely maternally transmitted. This strict dependence is crucial to underpin not only the history of their insect hosts; it might provide as well a strong input to the ongoing genetic analysis investigating the evolution of the vertebrate hosts of lice, such as dispersal, movements and the direct contact between modern and archaic humans.
In vitro feeding and long term in vitro breeding of the human body louse Pediculus h. humanus.
Birgit Habedank1,2, Tanja Bartmann2, Gabriele Schrader1 & Eberhard Schein2
1 Federal Environmental Agency , Postbox 33 00 22, 14191 Berlin, Germany. email@example.com
2 Free Univ Berlin, Institute for Parasitology and International Animal Health, Germany.
In vitro feeding studies of Pediculus humanus humanus of a rabbit-adapted strain revealed that the lice can feed blood through very thin membranes like Parafilm or Nescofilm. Fresh or frozen human blood or human blood transfusion units can serve as nutrition media (Habedank et al. 1999). The application of human blood transfusion units with an exceeded date of expiry was evaluated for usability in lice breeding by means of a non-automated feeding procedure. The body louse culture was successfully reared in vitro for up to 16 generations. Sensibility against a pyrethroid was compared between lice from the in vitro fed strain and a rabbit-adapted lice strain. Advantages and limitations of a long term in vitro breeding of body lice are discussed. The in vitro feeding of the human body louse through artificial membranes is not only important for animal welfare (rabbit as laboratory host), it also enables rearing body lice for investigations in molecular biology, genetics, for the studies on vector biology, behaviour, transmission of human pathogens and lice control.
Symbiotic bacteria associated with stomach disc of human lice Pediculus humanus and P. capitis.
Kayoko Sasaki-Fukatsu1, Ryuichi Koga1, Naruo Nikoh2, Kazunori Yoshizawa3, Shinji Kasai4, Minoru Mihara5, Mutsuo Kobayashi4, Takashi Tomita4 & Takema Fukatsu1
1 Inst. Biol. Res. Func., Natl. Inst. Adv. Indust. Sci. Tech. (AIST), Tsukuba 305-8566, Japan.
2 Div. Nat. Sci., Univ. Air, Chiba 261-8586, Japan.
3 Dept. Ecol. Syst., Hokkaido Univ., Sapporo 060-8589, Japan.
4 Dept. Med. Entomol., Natl. Inst. Infect. Dis., Tokyo 162-8640, Japan.
5 Dept. Environ. Biol., Jpn. Environ. Sanit. Cent., Kawasaki 210-0828, Japan.
Vertebrate blood is certainly nutritious but deficient in some nutritional components such as B vitamins, which is probably the reason why insects exclusively living on vertebrate blood all through their life, including tsetse flies, louse flies, bedbugs, assassin bugs, lice, etc., are generally in close association with endosymbiotic microorganisms (Buchner, 1965). It was back to the 1920's when the human lice were first reported to possess a large aggregate of bacteriocytes, called stomach disc, on the ventral side of midgut, wherein rod-shaped symbiotic bacteria are harbored (Sikora, 1919; Buchner, 1920). Since then, a number of histological (Ries, 1931; Eberle and McLean, 1983), embryonic (Ries, 1931; Baudisch, 1958), experimental (Aschner, 1932; 1934; Aschner and Ries, 1933; Eberle and McLean, 1982) and nutritional (Puchta 1954; 1955) studies have been conducted on the endosymbiotic system of the human lice. Despite the substantial body of early works on the lice endosymbiosis, microbial nature of the symbionts has been unknown to date. Hence, we determined 16S rRNA gene sequences of the symbiotic bacteria from the human body louse Pediculus humanus and the human head louse P. capitis. Molecular phylogenetic analysis demonstrated that the symbionts formed a distinct and well-defined clade in the Proteobacteria. The 16S rRNA gene sequences consistently exhibited AT-biased nucleotide composition and accelerated molecular evolution, as has been reported from obligate endosymbiotic bacteria of other insects. In situ hybridization revealed that in nymphs and adult males the symbiont was localized in the stomach disc, while in adult females the symbiont was not in the stomach disc but in the lateral oviducts and the posterior pole of the oocytes, confirming previous histological descriptions of the female-specific symbiont migration to ovary.
Evolutionary relationships of a new lineage of Enterobacteriacae living as an endosymbiont in Anoplura.
Julia M. Allen1, M. Alejandra Perotti, Jessica E. Light, Henk R. Braig, & David L. Reed1
1 Florida Museum of Natural History, Univ of Florida, USA.
Insects are an incredibly successful and diverse group. Part of the success of this group may be due to mutualistic endosymbiotic bacteria, which have enabled insects to radiate into nutrient poor niches such as blood feeding in the case of sucking lice, Anoplura. All Anoplura are thought to harbor primary endosymbiotic bacteria, which have remained unnamed. It is not known if the acquisition of a single endosymbiont was involved in the radiation of all of Anoplura. We have sequenced 16S rDNA from several species of Anoplura and reconstructed their evolutionary history, which can then be compared to that if their sucking louse hosts. We can thereby test not only the monophyly of the endosymbiont, but also the hypothesis of a single endosymbiosis event within Anoplura. In addition, some lineages of sucking lice parasitize mammals that have a rich fossil history, which permits the calibration of both louse gene trees as well as endosymbiont trees at nodes of cospeciation. We have recalibrated the clock for 16S rRNA substitution rates and compared our rate to that of Buchnera, the primary endosymbiont in aphids, calibrated by Moran and colleagues from the mid-1990s.
Molecular characterization of symbiotic bacteria isolated from columbiform bird lice.
Wendy Smith1, Colin Dale1, David Reed2 & Dale H. Clayton1
1 Dept of Biology, Univ of Utah, Salt Lake City UT, 84112, U.S.A.
2 Florida Museum of Natural History, Gainesville FL, 32611, U.S.A.
This talk will focus on symbiotic bacteria found in chewing lice of the genus Columbicola. These lice are host specific ectoparasites of Columbiform birds (pigeons and doves), where they feed on feathers and dead skin. Our preliminary phylogenetic analyses (see poster) demonstrate the occurrence of two clades of bacterial symbionts within the genus Columbicola, which we have dubbed Type I and Type II. Here we present further molecular characterization of bacteria from representatives of each of these clades, viz. bacteria from the louse species C. baculoides (Type I) and bacteria from the species C. columbae (Type II). First, we describe the use of pulsed field gel electrophoresis to determine genome size and age for each clade of bacteria. Second, we examine nucleotide base composition of our Type I and Type II bacteria, and compare these results with those for bacterial symbionts from other insects. Finally, we consider the implications of these findings with regard to the evolution of bacterial symbioses within the genus Columbicola.
Head louse infestations worldwide.
Kosta Y. Mumcuoglu
Dept of Parasitology, Hebrew Univ-Hadassah Medical School, Jerusalem, Israel. firstname.lastname@example.org
An increased rate of louse infestation in recent years has been reported from North and South America, Europe, Asia, and Australia. Synergized pyrethrins, pyrethroids (such as permethrin, d-phenothrin, sumithrin and bio-allethrin), lindane, carbaryl, malathion and oral ivermectin (“off label” use) are used to treat lice infested individuals. Alternative treatment modalities such as the use of “natural products” based on tea tree, coconut, anis and other essential oils are being used more and more to complement chemical products. These oils, if proven effective, have the advantage of being less toxic and because of their complexity, lice are less prone to develop resistance to them. Physical methods, e.g., the use of a louse comb alone or in combination with regular shampoo or conditioner are increasingly becoming the preferred methods of treatment. There are more frequent reports indicating that lice are developing resistance to insecticides, especially permethrin, but also malathion and carbaryl. The no-nit policy, i.e., the immediate dismissal of all children who have head lice, eggs and/or nits on their hair from school, camp or child-care settings and their readmition institution only when all head lice, eggs and nits have been removed, is being challenged by medical organizations, physicians and research groups and should be abandoned.
Epidemiology of human lice.
Dept of Dermatology, Univ Hospital Ghent, De Pintelaan 185, 9000 Ghent, Belgium.
Lice have been infesting mankind for thousand of years, but little is known about the epidemiology of pediculosis and the factors influencing the prevalence. Every year, new studies on the epidemiology of pediculosis are published in the international scientific literature. These studies should be read and interpreted with care because of the heterogeneity in the methodology. A first important factor is the selection of the population in which the screening is performed. The population can be chosen at random or may be a convenience sample. The way the population is chosen can have an important influence on the results of the screening. For instance, populations that have dealt with pediculosis in the past may be more enthusiastic to participate in a screening. However, the prevalence in these populations may also be higher and are therefore not representative for the entire community. The second key element in an epidemiologic study are the diagnostic criteria used, meaning the clinical findings that are used to ascertain the diagnosis. In case of pediculosis, the clinical findings can be eggshells or living lice. The presence of eggshells in absence of lice is a sign of a past infestation while the presence of lice represents an active infestation. The presence of an active infestation has important implications for the individual but also on the epidemiologic level. A third element is the diagnostic method. Several methods to diagnose pediculosis have been used in the international literature. Each method has advantage and disadvantages. Very little trials on the diagnostic accuracy of the detection methods have been published until now, making it difficult to make an evidence-based choice. Finally, it is also important to choose the appropriate statistical methods in order draw the right conclusions from the available data. The importance of several risk factors for pediculosis has been explored. These risk factors can be divided in three main categories: personal characteristics of the child (age, sex, hair type, hair colour and hair length), crowding (class, school, educational level) and socio economic status (profession, educational degree or income of the parents). The methodological aspects of epidemiologic studies on pediculosis will be covered and illustrated with examples from the recent literature. Furthermore, the importance of several risk factors in the prevalence of pediculosis will be discussed.
Pediculosis: yesterday and today.
Alda González1 & C. de Villalobos2
1 Center for Parasitological Studies and Vectors (CEPAVE) (CONICET-UNLP). 2 N° 584, 1900 La Plata, Argentina. email@example.com
2 Faculty of Natural Sciences and Museum, La Plata National Univ (UNLP). Paseo del Bosque s/n, 1900 La Plata, Argentina. firstname.lastname@example.org
Pediculosis has been documented through centuries, demonstrating that from the beginnings of history of humanity it has been closely related to man and his culture. In Latin America, pediculosis has been present since before Conquest times, according to a paleopathologic study on a 500-year-old mummy. In 1935, Zinsser foresaw that lice would not be exterminated and they would increase in amount even in populations considered to belong to the First World. This is something evident, considering that the percentages of pediculosis infestations have increased in almost every country. Argentina does not escape this world-wide situation. However, neither studies of its incidence on municipal, provincial or national scale nor government campaigns oriented to its prevention or control have been carried out. The purpose of this work is to study thoroughly this disease in the districts of La Plata and Dolores (Province of Buenos Aires, Argentina). In collaboration with medical professionals, teachers and sanitary officers, we worked on school age children and analyzed zones with the same structure and density but with different socio-economic status. Pediculosis cases, their causes and correlations with environmental, personal and institutional factors have been identified. From 45000 children treated, 38% and 45% presented pediculosis in the districts of La Plata and Dolores respectively. Thus, a 15% increase has been recorded in the middle social class since 2000. Through community work the causes leading to Pediculosis have been identified and the population has been advised to make its members spread the knowledge received. What moves us to confront this ectoparasitosis is an ecosystemic approach of health, which contemplates the health-environment relationship at microsocial levels, where the reflections of scientists, society and people representatives meet.
Individual treatments in the context of an effective strategy for the prevention of Pediculosis capitis in the UK.
Joanna Ibarra, Clarice Wickenden, Frances Fry, M. Jenner & A. Franks
Community Hygiene Concern, Manor Gardens Centre, 6-9 Manor Gardens, London N7 6LA, UK.
Individual cases of pediculosis capitis are not only a personal problem, but intrinsically a community problem. Exploratory studies on the incidence of head lice suggest that a transient reservoir of undetected, but contagious cases, perpetuates outbreaks. Primary school children are particularly vulnerable to repeated infestation. In the early 1970s, Donaldson applied the principles of infectious disease surveillance to pediculosis capitis. Nurses monitored the effect of engaging parents in an intensive detection/treatment campaign. Point prevalence surveys using standardised visual inspection showed that this co-ordinated approach halved the 16% infestation rate. This occurred even though a failing insecticide, lindane, was used for treatment. The introduction of malathion, which had a high degree of efficacy at that time, further reduced the rate. However, a low level of infestation persisted. This led Donaldson to conclude that the late detection of light cases is partly responsible for ongoing incidence. From 1989 onwards, the health charity, Community Hygiene Concern (CHC), has organised an educational programme on head lice. It culminates on designated Bug Busting Days, a development of the Donaldson model. The Departments of Health and Education commend school participation as, in their view, it offers the best strategy to prevent head lice from circulating. A Bug Buster Kit is used to provide parents with effective fine-tooth combs and tuition in the detection of asymptomatic cases. Families also have the option of using the kit to eradicate positive cases they diagnose, without recourse to medication. Today there is no treatment which kills louse eggs with certainty. Both CHC materials and the National Health Service leaflet “The prevention and treatment of head lice” stress the importance of checking accurately for hatching lice 5 days after using medication, and again at 12 days. Monitoring has shown that in the UK, promotion of the Bug Busting approach is reducing professional time spent with parents worried about head lice. Moreover, health authority expenditure on treatment drops by as much as 24% in the first year of implementation. We conclude that to manage pediculosis capitis effectively, individual and collective need must be met simultaneously. To provide an economic, community solution to the head louse problem, treatment must be couched within a strategy where prevention takes the lead.
Epidemiology of Pediculosis capitis in elementary schools of Buenos Aires, Argentina.
Claudia V. Vassena, Ariel C. Toloza, Paola González Audino, Gastón Mougabure-Cueto, Eduardo N. Zerba & María I. Picollo
Centro de Investigaciones de Plagas e Insecticidas (CITEFA/CONICET). Juan Bautista de La Salle 4397 (ALO1603). Villa Martelli. Buenos Aires. Argentina. email@example.com.
The infestation with the ectoparasite Pediculus humanus capitis is a worldwide problem, mainly affecting elementary children schools. Previous works in our laboratory have shown the evidence of permethrin resistance in populations of head lice from Buenos Aires. The aim of the present work was to evaluate the prevalence of head louse infestations in five primary schools from Buenos Aires. A total of 357 individuals (168 boys and 189 girls) were examined for head louse infestation. The entire head was screened carefully for a period of 5-10 min. The resistant levels of the evaluated primary schools ranged from 100 to 300. Lice were removed using an antilouse comb. Infestation was defined as the presence of adults, nymphs and nits. The data were analyzed statistically using the chi-square test. Pediculosis was observed in all the schools. A total of 40% children were found to be infested with P.h. capitis. There was a higher prevalence of infestation among girls (51.85%) than boys (26.78%) (_2=5.4, P=0.604). The most frequently infested children were aged between 6 and 9 years. Considering girls, the groups with more than 50% of infestation were aged between 6 and 10. On the other hand, the groups of boys with more than 30% of infestation were those aged 7 and 11. With respect to hair lenght, 99% of the examined children with long hair were girls, while 95% of the individuals with short hair were boys. Thus, an independent analysis concerning hair length was not possible to do. Prevalence differences between girls and boys could partially be explained by the fact that in girls it is more difficult to find and remove lice than in boys. Our results are in accordance with previous epidemiological works.
Diagnosis of head louse infestation by plastic detection comb: an epidemiological study in Turkey.
Cuneyt Balcioglu1, Ian F. Burgess2, Emin Limoncu1, Turan _ahin3, Yusuf Ozbel4, Cemal Bilaç3, Ozgur Kurt1 & Kim S. Larsen5
1 Celal Bayar Univ, Medical School, Dept of Parasitology, Manisa, Turkey.
2 Medical Entomology Centre, Insect Research & Development Ltd, Cambridge House Barrington Road, Shepreth, Royston, SG8 6QZ, UK.
3 Celal Bayar Univ, Medical School, Dept of Dermatology, Manisa, Turkey.
4 Ege Univ, Medical School, Dept of Parasitology, Bornova, Izmir, Turkey.
5 KSL Consulting, Ramløsevej 25 3200 Helsinge, Denmark.
This study compared visual inspection with detection combing on dry hair in diagnosis of head louse infestation and identified the risk of developing active infestation in people with nits but no detectable lice by follow up after a two week period. The study was conducted in two schools in Manisa region (western Turkey) and all the children were screened by the two diagnostic methods. Those with lice were offered open label treatment with 1% permethrin applied twice 7 days apart and the results monitored by detection combing on days 2, 7, 9, and 14 after the first treatment. Children with nits only were re-screened after 14 days to identify latent infestations missed at the first examination. Of 461 children, 214 (46%) had nits but only 96 (21%) had active infestation with live lice. Detection combing was 4.6 times (95% CI, 2.9 to 7.2) more effective than visual inspection for finding live lice. Overall treatment success with 1% permethrin was 87% on day 14. Ten children (7% of those with nits) converted to positive infestation with lice by day 16. In this population, detection combing of dry hair was significantly more effective than visual screening for finding live lice. Both methods showed higher levels of infestation than previous studies conducted in that region of Turkey. The presence of nits was not indicative of live lice with limited risk of converting to an active infestation. Treatment with 1% permethrin was as effective as in previous Turkish studies, with no indication of resistance to the insecticide.
Physicians' answers to a questionnaire regarding head louse infestations in Turkey.
Aysegul Taylan-Ozkan,1, Ozlem Coskun2, Mesut Mungan1, Cahit Babur1, Mustafa Ertek1 & Kosta Y. Mumcuoglu3
1Parasitology Laboratory, Refik Saydam National Institute of Health, Ankara, Turkiye.
2 Dept of Health Education, Medical School, Gazi Univ, Ankara, Turkiye.
3 Dept of Parasitology, Hebrew Univ-Hadassah Medical School, Jerusalem, Israel.
Epidemiological studies conducted in Turkey showed that the infestation rate of schoolchildren with head lice varies from 2-37%, depending on the region and the socio-economic level of the children. The average infestation rate in schools is approximately 11%, and there are approximately 1.8 million infested students in Turkey each year. In this study, we examined the knowledge of physicians regarding head louse infestations. A questionnaire with 20 questions testing their general knowledge on lice and 19 questions related to their personal experience was send to 33 medical students in the last year of their education and 59 physicians with different specializations. None of the questioned students or physicians answered all questions correctly. Only 8.7% correctly answered more than 15 questions, 44.6% correctly answered 11-15 questions, 45.7% 6-10 questions and 1% 1-5 questions. There were no significant differences between students and physicians and no differences between the level of knowledge and number of years after graduation from medical school. In conclusion, we think that the knowledge of Turkish physicians about lice infestation is inadequate and unrelated to their medical experience. Because lice are a public health problem and because infestation can cause psychological and emotional problems, measures should be taken in primary health care for the control of lice. A national guideline should be prepared and health workers should be trained in this subject.
Evolution of head lice control in Argentina after permethrin resistance.
Eduardo N. Zerba
Centro de Investigaciones de Plagas e Insecticidas (CITEFA/CONICET). Juan Bautista de La Salle 4397 (B1603ALO). Buenos Aires. Argentina. firstname.lastname@example.org
The continued use of pediculicides containing permethrin in Argentina resulted in high levels of resistance in Pediculus humanus capitis. This resistance phenomenon with serious control failures was first reported in 1998. Cross-resistance between pyrethroids insecticides was also demonstrated. Because the serious problem of control failures our Center initiated in the last 90s a program designed to the search of alternative formulations to control the pyrethroid resistant head lice. Old active principles with a mode of action different to pyrethroids such as lindane, carbaryl and malathion showed to be effective against pyrethroid resistant populations but they were rapidly rejected because their undesirable toxicological properties. A novel active principle successfully tested in our Laboratory as pediculicide was the microbial toxin spinosad with favorable properties of selectivity and human safety. This insecticide showed to be a very active pediculicide against pyrethroid resistant lice and their eggs. Looking for novel products with more favorable toxicological properties we evaluated the pediculicidal effect of fatty alcohols. All the tested n-alcohols containing chains from 8 to 12 carbon atoms showed knockdown and mortality effect. Pediculicide activity systematically increased with increase in the number of carbon atoms of the alcohol chain. Maximum activity was observed for dodecanol, which was incorporated in commercial pediculicide formulations developed in Argentina. The search of novel and safe compounds is now focused in essential oils, which fumigant and contact pediculicide effect likewise the repellent properties are being tested.
Control of Pediculosis: Status of resistance and monitoring.
J. Marshall Clark
Dept of Veterinary & Animal Science, Univ of Massachusetts, Amherst, MA 01003-0230 USA.
Pediculosis, the infestation by head and body lice, is the most prevalent parasitic infestation of humans and occurs in both developed and underdeveloped nations. Human lice vector a number of diseases, including epidemic typhus, and are the source of a variety of secondary infections. Current pediculicidal products are failing worldwide due to resistance. The development of an in vitro rearing system has allowed the mass rearing of pediculicidal-susceptible and -resistant strains, the determination of the extent, mechanism and genetics of resistance to permethrin/pyrethrins and malathion. A resistant haplotype (M815I, T917I L920F) is responsible for permethrin/pyrethrin resistance and cross-resistance to DDT via a knockdown resistant (kdr) mechanism. A high-throughput diagnostic, based on these mutated alleles and using a SISAR format, allows monitoring resistant populations. Malathion resistance is due primarily to an enhanced malathion carboxylesterase. Natural products have been identified that are toxic, repellent and/or attractive and are amenable to resistance management strategies.
Role of esterases in enhanced detoxication of pyrethoids in Pediculus humanus capitis from Buenos Aires (Argentina).
Paola González Audino2, S. Barrios1, María I. Picollo1 & Eduardo N. Zerba1
1 Centro de Investigaciones de Plagas e Insecticidas (CITEFA/CONICET) J. B. De Lasalle 4397 (B1603ALO) Villa Martelli. Buenos Aires, Argentina. email@example.com
2 Escuela de Posgrado. Universidad Nacional de San Martin (UNSAM). Av 52 N 3563. (1650). Buenos Aires, Argentina.
Enhanced metabolism by oxidative enzymes is known to be a major cause of pyrethroid resistance in insects. We demonstrated in a previous work the importance of enhanced metabolism by monooxygenases in populations of head lice from Buenos Aires, Argentina exhibiting different levels of resistance to permethrin. A positive correlation was established between enzyme activity and the LD50 to permethrin in the resistant field populations. In this work, we evaluated the role of specific and non-specific esterase in head lice populations of Buenos Aires with different levels of resistance to permethrin. Taking into account that esterase activity is substrate dependent, four different esters were used as unspecific substrates in order to give a better characterization of the possible role of these enzymes in the resistance phenomena. The unspecific substrates were phenylthioacetate, ±- and ≤- naphtyl-acetate, and p-nitrophenyl acetate. All the resistant head lice populations studied in this work showed detoxifying activity of esterase significantly greater than the susceptible one with all the substrates used for the determination. Accordingly, esterase activity seems to be a contributive mechanism to the pyrethoids detoxification in resistant head lice. Unspecific substrates could be no enough good model of the real pyrethroid esterase activity. Thus, with the aim of obtaining a specific substrate for pyrethroid esterases, 7-coumaryl permethrate was synthesized, an ester structurally similar to permethrin, with the same acid moiety. The hydrolysis of this ester yields fluorescent 7-OH coumaryl, what allows the use of microfluorometric methods for quantification of esterase activity. This method is highly sensitive and the substrate has a structure similar to pyrethroid insecticides. Results of pyrethroid esterases activity obtained with the new substrate showed that these enzymes contribute to the detoxifying activity in resistant populations, although a correlation between pyrethroid esterase activity and resistance ratios was not found. Therefore, in this work we established that esterase activity against specific and non-specific substrates is increased in pyrethroid resistant populations of head lice from Buenos Aires.
Physiochemical parameters related with the bioactivity among essential oil components against permethrin-resistant Pediculus humanus capitis (Anoplura: Pediculidae).
Ariel C. Toloza1, Gastón Mougabure-Cueto1, J. Zygadlo2, Eduardo N. Zerba1 & Maria I. Picollo1
1 Centro de Investigaciones de Plagas e Insecticidas (CITEFA/CONICET). Juan Bautista de La Salle 4397 (1603). Villa Martelli. Buenos Aires. firstname.lastname@example.org
2 Cátedra de Química Orgánica y Productos Naturales. FCEF y N. UNC., IMBIV-CONICET, Córdoba, Argentina.
Resistance to permethrin and other pyrethroids in Pediculus humanus capitis from Buenos Aires, Argentina, was previously reported by our laboratory in 1997. The use of essential oils for the control of resistant head lice is an interesting alternative to permethrin because they are environmental friendly and not acutely toxic to mammals. Previous studies in our laboratory have shown the fumigant and repellent activity of native and exotic essential oils and their components. The purpose of the present study was to determine physiochemical parameters related with pediculicidal activity relationships among the effective essential oil components. Head lice were collected from heads of infested children 5-12 yr old, using an antilouse comb. Once the fumigant (knockdown time 50% KT50s) and repellent (Repellency indexes RI) data were collected, a multiple linear regression analysis was performed to examine relations among KT50s, RIs and either their respective vapor pressures or octanol-water partition coefficient values (log P). Fumigant regression analysis revealed a significant correlation between KT50 and corresponding vapor pressures of the effective components of essential oils when considered as a single predictor (r2=0.42, F=5.74, P0.05). thus, the more volatile the compound, the more effective it was as a fumigant. in contrast, kt50s were independent of log p values for the same compounds (r2=0.001, f=0.01, p0.937). when both predictors were included, the resulting model showed a better correlation (r2=0.73, f=8.14, p0.05). concerning repellency regression analysis, either the regressions between ris and vapor pressures or ris and log p showed r2=0.001 and p0.05. Most of the components that were effective in vapor phase were not the same that were effective as repellents in contact exposure. Our results provide indications of a possible difference between the knockdown and repellency targets of essential oils components.
The 7 cis- or trans-coumaryl permethrate esterases as a possible biochemical marker of pyrethroid resistance in Pediculus humanus capitis.
Pablo L. Santo Orihuela, María I. Picollo, Eduardo N. Zerba & Héctor Masuh
Centro de Investigaciones de Plagas e Insecticidas (CITEFA-CONICET). Juan Bautista de La Salle 4397. (B1603ALO), Buenos Aires, Argentina. email@example.com
Increased hydrolytic metabolism of pyrethroid insecticides has been associated with resistance among Pediculus humanus capitis populations, and particularly with those enzymes that hydrolyze the ester group of the insecticides (esterases). Earlier attempts have been made to synthesize pyrethroid surrogate substrates for determining pyrethroid-cleaving esterase, but often these new substrates vary in structure from the pyrethroids or lack sensitivity. The aim of this work was the synthesis of a new substrate as similar as possible to permethrin and sensitivity enough for studying levels of esterase enzymes in individual head-lice. The cis- and trans-7-hydroxy coumaryl permethrates (7-CP) were synthesized by reacting the corresponding cis- and trans- permetrinic acid chloride with the 7-hydroxicoumarin (7-OHC). The hydrolysis of 7-CP by esterase yields 7-OHC, a fluorescent product which was monitored by spectrofluorometry. Hydrolysis of new substrates by human louse esterase was conducted with permethrin resistant P. humanus capitis (Phc) and susceptible P. humanus humanus (Phh) individual homogenates on 96-well microplates. Fluorescence production of 7-OHC was measured at 440 nm. Histograms of individual activities showed normal distributions, they were different between susceptible and resistant lice. The average activity for the cis- 7-CP was 1.38 pmol/min for Phh and 3.71 for Phc (p 0.05) whereas the trans- isomer showed an activity of 3.28 pmol/min (phh) and 7.30 pmol/min (phc) (p0.01). all the susceptible insects showed activities for the cis- isomer below 1.9 pmol/min and only 8.33 % of resistant insects had activities under this value. with trans- isomer all the susceptible insects had activities lower than 5.3 pmol/min and 12.5 % of resistant lice had activities lower than this number. this increased frequency of individuals with a greater capacity to hydrolyze cis- or trans-7-cp represent a possible biochemical parameter for detecting resistant populations to pyrethroid insecticides.
Pyrethroid resistance in eggs of Pediculus humanus capitis (Phthiraptera: Pediculidae) from Argentina.
Gastón Mougabure-Cueto, Eduardo N. Zerba & María I. Picollo
Centro de Investigaciones de Plagas e Insecticidas (CITEFA-CONICET), Juan Bautista de La Salle 4397 (B1603ALO), Villa Martelli, Buenos Aires, Argentina. firstname.lastname@example.org
Although all studies about insecticide resistance were evaluated on the larval or adult stages of head lice, the development of insecticide resistance in embryos should not be underestimated as a contributive cause of control failures. The aim of this research was to study insecticide resistance in eggs of P. humanus capitis populations whose pyrethroid resistance was demonstrated in postembryonic stages. In addition, the resistance profile to pyrethroid and non-pyrethroid insecticides was comparatively studied in adults and eggs. The head lice (HL) were collected from infested children from elementary schools of Buenos Aires. Three populations were selected according to the permethrin resistance levels assessed in previous studies. A body lice colony was used as susceptible strain. Egg toxicity was evaluated using an immersion technique. Ten late development eggs selected according to external markers were immersed in the insecticide acetonic solutions. Adult and nymph toxicity were done by topical application. Each louse was treated with 0.1 µl of the insecticide solution on the dorsal abdomen. Data from bioassays were subjected to probit method. Eggs of all head lice populations showed high levels of resistance to permethrin (LDR from 884 to 4.876), d-phenothrin (LCR from 173 to 1433) and DDT (LCR from 118.6 to >400), and low resistance to carbaryl. In concordance, adults were high resistance to permethrin (LDR from 16.6 to 265.6), d-phenothrin (LDR from 8.2 to 974.7) and DDT (LDR from 25.3 to >74.6), and low resistance to carbaryl. Results presented here demonstrated high resistance to pyrethroids in eggs of P. humanus capitis, in common with that assessed for nymphs and adults. Additionally, results concerning to the cross-resistance to DDT and carbaryl, suggested that altered site of action and increased oxidative metabolism are cause of insecticide resistance in head lice populations from Argentina.
Preliminary studies of oral and topical ivermectin in the treatment of head lice.
Craig G. Burkhart
Medical Univ of Ohio at Toledo and Ohio Univ College of Osteopathic Medicine, Sylvania, Ohio, USA.
Ivermectin is the drug of choice for a variety of parasitic diseases in humans and animals due to its broad spectrum of activity and wide margin of safety. Delivery modes include oral, topical and subcutaneous injections. Its main method of biological activity is its effects on neurotransmitter substances, glutamate and aminobutyric acid. Oral ivermectin is effective for parasites which feed off host blood. Of note, the half-life of this drug is 28 hours. Thus in the case of pediculosis capitis, a second dose of therapy would be essential 7 to 10 days following the initial therapy to eradicate any hatched eggs over the ensuing week. Topical ivermectin has been reported to be successful in a 0.8% dosage by Youssef and a 1.0% concentration by Victoria. Our preliminary studies support the effectiveness of ivermectin both topically and orally and suggest that a lower topical concentration may be successful by evaluation using standardized pediculicidal testing procedures.
The bug busting wet combing method to detect and eradicate head lice.
Joanna Ibarra, Frances Fry, Clarice Wickenden & Jane L. Smith
Community Hygiene Concern, Manor Gardens Centre, 6-9 Manor Gardens, London N7 6LA, UK.
The Bug Busting wet combing method follows a precise protocol using specific plastic combs. The Bug Buster Kit was conceived by a UK health charity, Community Hygiene Concern, as an educational tool to empower parents in the management of head lice. It aims to impart a clear understanding of what lice look like, how to detect them reliably and how to break their life-cycle, without egg removal or using pesticides. It is used in combination with ordinary shampoo and ordinary hair conditioner at four combing sessions spaced evenly over two weeks. No medicated products are required. This is attractive to families who do not wish to use them. Additionally, the Bug Buster Kit is used to check the success of any treatment. This is important in the UK because no treatment available is reliably ovicidal. A single Bug Buster Kit is reusable by a whole family, offering continuity of care in one product. This is economical. Anywhere that there is access to running water, it is a practical, sustainable remedy for head lice that a family can always have to hand. Numerous judgements have been passed in the literature on the efficacy of combing to detect and eradicate lice without enough discrimination between combs and methods of use. Since a pilot Bug Buster Kit was launched in 1995, it has been supposed that a generic “wet combing” exists. Whether it is a doctor's receptionist, a community nurse, or www.besttreatments.co.uk, telling a family to obtain a fine-tooth comb and a bottle of conditioner, or possibly vegetable oil instead, it is the particular advice which the family takes, that is put to the test. It is necessary to differentiate between the first and later Bug Buster comb designs. The efficacy of the current Bug Buster comb has been found to positively influence the effectiveness of the method. We feel that, with today's emphasis on evidence-based medicine, it should be self-evident to researchers that different intervention components produce different outcomes. Our observations confirm that the egg stage can last at least 10 days. We recommend combing sessions on days 1, 5, 9 and 13 because we usually find there are still some nymphs on day 13. These hatched after the combing session on day 9. This leads us to question the validity of the common recommendation to dose twice with medicated products a week apart (day 1 and day 8). This regimen, intended to kill all lice emerging from eggs that were inadequately treated at the first dose, misses those that hatch later than day 8. We believe that the claims of all treatment products for head lice should be independently assessed using the Bug Busting wet combing method, and the results made readily accessible to the population at risk. This will help to prevent public expenditure on products which are the cause of time-wasting disappointment.
Pediculicides in the bathroom cabinet.
Ian F. Burgess
Medical Entomology Centre, Insect R&D Limited, Royston, UK. email@example.com
Little more than a decade ago, if you asked most people to identify a pediculicide agent the answer from most would unequivocally have named a neurotoxic insecticidal chemical. Although that may still be the case for some people, or in some countries, there is now a plethora of materials claiming pediculicidal action, many of which are not licensed as either medicines or medical devices. Do these materials work to eliminate infestation and are there other simpler ways to kill lice? Two recent publications have indicated that compounds present in the bathroom cabinet of almost every household in the western world are potentially just as effective as recognised pediculicide products. We have observed the activity of two of these compounds in both laboratory studies and clinical use with the conclusion that they are potentially highly effective for killing lice and, provided they are applied thoroughly for killing louse eggs. Cetearyl/stearyl alcohols and cetrimonium chloride are surfactant and moisturising agents in a wide range of toiletry preparations, particularly those used for conditioning hair. Both types of compound exhibit activity against lice in a dose dependent manner. If you leave them in contact for a long enough time lice and their eggs die. This has important implications for those methods for treatment of infestation that involve using conditioners as lubricants for combing out lice as the longer the process takes the better the chances of success for two reasons. The first may be that the longer combing is carried out the greater the chance that all mobile lice will be found. However, if the process takes a long enough time, and the conditioner lubricant is left in the hair at the end of the process, it appears that there is an even higher probability of success in treatment even if the carer is not very good at combing out lice. Data supporting these statements will be presented.
What is a good randomised control trial of a pediculicide?
Stephen C. Barker1, Ciara S. Casey2 & Ian F. Burgess3
1 Parasitology Section, School of Molecular & Microbial Sciences, & Uniquest Pty Ltd, Univ of Queensland, Qld. 4074. Auatralia. firstname.lastname@example.org
2 School of Bioscience Cardiff Univ, Main Building, Park Place Cardiff CF10 3TL, UK. doddcs@Cardiff.ac.uk
3 Ian F Burgess, Medical Entomology Centre, Insect Research & Development Limited, Cambridge House, Barrington Road, Shepreth, Royston, SG8 6QZ, UK. email@example.com
There are more people in the industrialised world who are infested with head lice, Pediculus capitis, now than at anytime since the introduction of insecticides. Head lice and their eggs may be pulled from the hair of subjects or killed with pediculicides. Pediculicides have been used to treat infestations of lice since at least the time of Napoleon who reputedly instructed his troops to put the petals of Chrysanthemum flowers in their uniforms to kill clothes (body) lice (P. humanus). There have been hundreds of in vivo trials of pediculicide. Most trials were not published but there is at least some information available on over 75 trials. The 2006 revision of the Cochrane Review of Interventions for Preventing Head Lice examines 36 studies (at last count): most do not conform to any recognised standards of execution or reporting and as yet there is no consensus on what constitutes a good randomised controlled trial (RCT) of a pediculicide. There may never be a consensus on what is an ideal RCT of these preparations, but doubtless, we can improve the design of trials. We will address the following questions: (i) The application of ICH-GCP to trials of pediculicides; (ii) How important is blinding? Is there a place for open studies?; (iii) What should be the “wash out” time since previous treatment, and what constitutes “previous treatment”?; (iv) Should researchers use a standard set of categories of adverse events? We will propose a possible set of categories of adverse events?; (v) How much detection-combing should there be at follow-up examinations eg at days 1, 4, 7 and 14?; (vi) Were the designs of the RCTs published since the Cochrane Review of interventions for treating head lice (February 2001) any better than pre-Cochrane review RCTs? We will precise the RCTs that have been published since February 2001; (vii) How important to control are repellents?; (viii) Should we standardise terms? For example, when might the terms lousicidal, ovicidal and pediculicide be used? (ix) How indicative of efficacy against head lice, P. capitis, are studies of laboratory strains of clothes (body) lice, P. humanus?; (x) How important are multi-centre studies?; (xi) Pediculosis is not a self limiting condition so are placebo-controlled trials feasible and ethical?; (xii) Is there a place for herbal treatments/remedies for pediculosis?; and (xiii) Do we need to design better trials to assess the effectiveness of combing treatments such as BugBusting? We will propose inclusion and exclusion criteria and a trial-design for discussion, and will table the latest Cochrane Review of Interventions for Preventing Head Lice for comment and discussion.
Clinical aspects of lice infestation.
Craig N. Burkhart
Dept of Dermatology, Univ of North Carolina at Chapel Hill, USA.
Lice infestation remains a prevalent disease worldwide that may cause pruritus, inflammation, and potential social stigma. Several other well-studied cutaneous diseases have similar dermatologic and psycho-social manifestations to lice infestation from which parallels may be drawn. As with many other dermatologic diseases, multiple over-the-counter and prescription medications are available for the treatment of lice infestation with the effectiveness depending on proper application, patient compliance, and resistance patterns. Presented will be an overview of various clinical aspects of lice infestation as compared with other dermatologic diseases.
An effective non-chemical treatment for head lice: a lot of hot air.
Dale H. Clayton
Dept of Biology, Univ of Utah, Salt Lake City UT, 84112, USA.
Head lice (Pediculus humanus capitis) are a major irritant to children and their parents around the world. Each year millions of children are infested with head lice, a condition known as pediculosis, which is responsible for tens of millions of lost school days. Head lice have evolved resistance to many of the currently used pediculicides. Therefore, an effective new treatment for head lice is sorely needed. In this talk I describe the results of a 5 year study examining the effectiveness of several methods that use hot air to kill head lice and their eggs. We tested six treatment methods on a total of 169 infested individuals. Each method delivers hot air to the scalp in a different way. We evaluated how well these methods kill lice and their eggs in situ. We also performed follow-up inspections to evaluate whether the sixth, most successful, method can cure head louse infestations. All six methods resulted in high egg mortality (≥88%), but they showed more variable success in killing hatched lice. The most successful method, which used a custom-built machine called the LouseBusterTM, resulted in nearly 100% mortality of eggs and 80% mortality of hatched lice. The LouseBusterTM was effective in killing lice and their eggs when operated at a relatively comfortable temperature, slightly cooler than a standard blow dryer. Virtually all subjects were cured of head lice when examined one week following treatment with the LouseBusterTM. There were no adverse effects of treatment. Our findings demonstrate that one 30minute application of hot air has the potential to eradicate head lice infestations. In summary, hot air is an effective, safe treatment, and one to which lice are very unlikely to evolve resistance.
Water - is it the “Achilles heel” of sucking lice?
Ian F. Burgess
Medical Entomology Centre, Insect R&D Limited, Royston, UK. firstname.lastname@example.org
It is well known that anopluran lice die relatively rapidly after removal from their hosts. Death is due to dehydration resulting from inability to replenish body water through feeding. We have found that human head lice and body lice lose water continually until death. It has long been recognised that the cuticular lipid of lice is not “waxy” like most terrestrial arthropods and, therefore, is likely to be less effective as a water barrier for prevention of water loss or as a waterproofing layer to prevent water ingress. Lice immersed in water exhibit a “steady state” in which the mass varies little by only minor fluctuations over a period of more than 4 hours. After 4 hours some lice increase in mass as a result of water entering the haemocoel, apparently by osmosis across the cuticle. Lice immersed for periods over 8 hours become turgid and bloated. However, if such lice are then dehydrated to normal appearance a proportion recover and are potentially viable, provided they can gain access to a host for feeding. Unlike other haematophagous insects, lice do not produce liquid or diuretic faeces to eliminate excess water ingested with the blood meal either during feeding (as in mosquitoes) or immediately after (as in blood sucking bugs). Instead, water is actively excreted by a form of transpiration. High levels of transpiration can be detected during feeding and after feeding can be monitored continuously by measurement of changes in body mass from which the proportions of water and faecal material can be easily differentiated. Engorged head lice excrete most of the water from a blood meal in approximately 120 minutes whereas for laboratory reared body lice this time has been extended by selection to around 24 hours. The rate at which water is lost is influenced by differences in temperature, humidity, and insect activity. Physical blockage of all the spiracles of a louse, using an occlusive agent such as petroleum jelly, virtually eliminates measurable water loss. If thoracic spiracles are occluded, and the abdominal spiracles left open, water loss occurs at the same rate as for intact insects. In contrast, if the abdominal spiracles are occluded and thoracic spiracles left open the rate of water loss is approximately doubled. It has long been known that occlusive materials such as petroleum jelly, mineral oils, and fixed vegetable oils can kill head lice but the mechanism has normally been misattributed to asphyxiation. Observation of lice with blocked spiracles suggests that death occurs as a result of osmotic stress induced by inability to excrete water. The most extreme form of this can be observed experimentally in laboratory reared body lice because they ingest more blood than head lice. In this model, occlusion of spiracles often results in gut rupture.
Susceptibility of human head lice, Pediculus humanus capitis De Geer (Phthiraptera: Pediculidae) to entomopathogenic nematodes (Steinernematidae, Heterorhabditidae) from Argentina.
M. M. de Doucet, M. B. Miranda & M. Alejandra Bertolotti
Cátedra de Parasitología, Laboratorio de Nematología, Centro de Zoología Aplicada. Facultad de Ciencias Exactas, Físicas y Naturales. Universidad Nacional de Córdoba, Casilla de Correo 122. 5000 - Córdoba, Argentina. email@example.com
Nematodes belonging to the genera Steinernema and Heterorhabditis can be used for biological control of insects, as an alternative to chemical insecticides. Infective juveniles (IJ) of these nematodes kill a wide range of insects within 24-48 h. The aim of this work was to evaluate the susceptibility of human head lice to four Argentine isolates. The nematodes used were: S. rarum (Doucet, 1986) from Noetinger (NOE isolate), S. feltiae (Filipjev, 1934) from Los Chorrillos, (LCHOR isolate), and H. bacteriophora Poinar, 1976 (OLI and RN isolates), from Oliva, and Río Negro, respectively. The stages of human head lice considered were: adults, nymphs, and eggs. They were put in contact with nematodes (100 IJ/insect) in Petri dishes. The experiences were carried out at 25 °C. Mortality percentage was recorded 36 h after exposure. Dead insects were dissected to verify that mortality was caused by nematodes. Adults and nymphs of head lice were parasitized by H. bacteriophora and S. rarum; contrarily, no parasitism was observed with S. feltiae. Eggs were resistant to all nematode isolates. The greatest mortality was caused by H. bacteriophora RN (84% and 100% for adults and nymphs, respectively). Exposure to H. bacteriophora OLI and S. rarum resulted in mortality percentages lower than 65%. Dissections of parasitized stages showed adults of nematodes of first generation. Significant differences in mortality percentage were observed (100% with H. bacteriophora and 0% with S. feltiae). These differences are related to the specificity of nematodes and may be caused by: Ecological and mechanical factors (finding and penetrating the insect), and physiological factors (capacity of the bacteria to grow and colonise the hemocel). H. bacteriophora and S. rarum were able to infect head lice, whereas S. feltiae was not. It is known that IJs of Steinernema enter to the hemocel through natural openings only, while Heterorhabditis IJs can also enter through soft cuticular areas using their dorsal tooth. In the case of P. humanus capitis, penetration by oral and anus orifices would not be possible because of the buccal apparatus morphology and the intense activity of excretion in this insect. Therefore, the most common entrance way is through the spiracles. The diameter of these orifices in head lice was lower than 30 µm. This small size avoids penetration of IJs of S. feltiae because their body diameter is greater than 30 µm. The susceptibility of P. h. capitis to Steinernematidae and Heterorhabditidae has been demonstrated for the first time. Although the control of these human parasites with entomopathogenic nematodes is not feasible because of their habits, the possible use of nematode toxins is an interesting aspect that needs to be evaluated in further studies.
Resistance to insect growth regulator insecticides in Australian sheep louse (Bovicola ovis Schrank) populations.
Peter J. James1, G. W. Levot2, N. Sales2, S. E. Hook1 & A. P. Cramp1
1 Animal Research Institute, Dept of Primary Industries and Fisheries, 665 Fairfield Road, Yeerongpilly Qld 4105, Australia.
2 Elizabeth Macarthur Agricultural Institute, NSW Dept of Primary Industries, Woodbridge Road, Menangle NSW 2568, Australia.
The first backline treatments for sheep lice control, based on synthetic pyrethroid pesticides (SPs), were introduced for use in Australia in 1981. Backline applications became the predominant method of treatment for sheep lice control because of their substantial management advantages. Resistance to synthetic pyrethroid (SP) based backline treatments was confirmed in the late 1980s and subsequently became widespread. Development and spread of resistance was associated with an upsurge in the prevalence of lice in Australian sheep flocks which only fell following the introduction of backliners based on the insect growth regulator (IGR) insecticides diflubenzuron and triflumuron. In recent years there have been recurring reports of poor effectiveness with IGR backliners. However, because of a lack of suitable resistance testing methods, whether breakdowns with IGR treatments were due to management factors, environmental conditions, a change in insect susceptibility, or a combination of circumstances has been unclear. This presentation reviews the history of resistance development in Australian sheep lice populations and presents results that suggest a change in lice susceptibility is involved in at least some instances of control breakdown with IGR backliners.
The relationship between louse numbers and pruritis in sheep: How good is rubbing as an indicator of infestation?
Peter J. James1, 2 & F. Bartholomaeous 1
1 South Australian Research and Development Institute, GPO Box 397, Australia.
2 Current address, Animal Research Institute, Dept of Primary Industries and Fisheries, 665 Fairfield Road, Yeerongpilly QLD 4105, Australia.
Sheep lice (Bovicola ovis Schrank) are one of the three main parasite problems of the Australian sheep industry. Historically control has relied almost exclusively on preventative and therapeutic application of insecticides. However, growing community sensitivity to the widespread use of chemical therapeutics and problems with the development of resistance now necessitate a more integrated approach. Development of effective integrated pest management (IPM) programs for louse control relies on convenient methods of detecting and assessing the extent of an infestation. Currently infestations are detected almost exclusively by inspection of sheep and most wool growers use the presence of rubbing sheep as an indicative sign of lice. There have been few studies of the temporal development and variability in initiation of pruritic behaviour in sheep infested with lice. This paper reports the results of a study to assess the quantitative temporal relationship between the development of an infestation, observation of pruritic behaviour and appearance of deranged fleece in Merino sheep subjected to a standardised louse challenge. The results indicate that sheep begin to exhibit pruritic behaviour and deranged fleece relatively early in the development of an infestation and with numbers of lice that may be difficult to detect by direct inspection. Implications of the findings for the use of pruritis as an indicator of lice in the design of integrated control approaches will be discussed.
The controlled crossing on Eucalyptus species as a potential technique to improve the pediculicidal activity of essential oils.
Alejandro Lucia, Ariel C. Toloza, H. Masuh, Paola González-Audino, Eduardo N. Zerba & María I. Picollo
Centro de Investigaciones de Plagas e Insecticidas (CITEFA/CONICET). Juan Bautista de La Salle 4397 (1603). Villa Martelli. Buenos Aires. Argentina. firstname.lastname@example.org; email@example.com
Previous reports have shown the permethrin resistance problems concerning human louse control from Buenos Aires, Argentina. One alternative to synthetic pyrethroids is the use of essential oils due to their low mammalian toxicity. A previous study has shown the effective fumigant activity of the essential oils of Eucalyptus species and their main components such as 1.8 cineole and -pinene. The purpose of the present work was to study the fumigant activity of five Eucalyptus essential oils, i.e., E. grandis, E. camaldulensis, E. tereticornis and their hybrids E. grandis x E. camaldulensis and E. grandis x E. tereticornis - against permethrin-resistant head lice from Buenos Aires. Essential oils were obtained by hydrodistillation of vegetal material collected in an experimental plot of our laboratory. Head lice were collected from heads of infested children 5-12 yr old, using an antilouse comb. Fumigant activity was evaluated in an enclosed chamber. The number of knockdown head lice was recorded every 5 min for 1h, and then a Probit analysis was made to determine the knockdown time 50% (KT50) of the tested essential oils. There was a significant difference of vapor effect among the hybrids and their parents. Both hybrids were more effective than the original ingredients. E. grandis x E. camaldulensis and E. grandis x E. tereticornis showed KT50 values of 12.99 and 13.63 min, respectively; while E. grandis, E. camaldulensis and E. tereticornis showed values of KT50 of 25.57, 35.14 and 31.31 min, respectively. It is interesting to note that the GC-MS analysis showed qualitative and quantitative differences in the essential oil composition of the hybrids, in comparison with their parents. Additionally, yields obtained from hybrids individuals were almost two times greater than those obtained from their parents. Our results suggest the potential use of the controlled crossings technique to obtain increased yield and higher effective essential oils against head lice.
The role of body size in host specificity: Reciprocal transfer experiments with feather lice.
Dale H. Clayton and Sarah E. Bush
Dept of Biology, Univ of Utah, Salt Lake City UT, 84112, USA.
Although most parasites show at least some degree of host specificity, factors governing the evolution of specificity remain poorly understood. Many different groups of host-specific parasites show a striking correlation between parasite and host body size, suggesting that size reinforces specificity. We tested this hypothesis by measuring the relative fitness of host-specific feather lice transferred to pigeons and doves that differ in size by an order of magnitude. To test the general influence of size, we transferred unrelated groups of “wing” and “body” lice, which are specialized for different regions of the host. Lice were transferred in both directions, from a large native host species, the Rock Pigeon (Columba livia), to several smaller hosts, and from a small native host species, the Common Ground-dove (Columbina passerina), to several larger hosts. We measured the relative fitness (population size) of lice transferred to these novel host species after two louse generations. Neither wing lice nor body lice could survive on novel host species that were smaller in size than the native host. However, when host defense (preening behavior) was blocked, both groups survived and reproduced on all novel hosts tested. Thus, host defense interacted with host size to govern the ability of lice to establish on small hosts. Neither wing lice nor body lice could survive on larger hosts, even when preening was blocked. In summary, host size influenced the fitness of both types of feather lice, but through different mechanisms, depending on the direction of the transfer. Our results indicate that host switching is most likely between hosts of similar body size. This finding has important implications for studies of host-parasite coevolution at both the micro- and macro-evolutionary scales.
Galápagos hawks and their chewing lice: A model system for studying host-parasite ecology.
Noah K. Whiteman & Patricia G. Parker
University of Missouri-St. Louis, U.S.A.
Oceanic islands, due to their ecological simplicity, are excellent contexts in which to study host-parasite interactions. Since 2001, we have studied the ecological, epidemiological and evolutionary dynamics among >200 individuals of the cooperatively polyandrous Galápagos Hawk (Buteo galapagoensis) and their ectoparasites, including three chewing lice (Colpocephalum turbinatum, Degeeriella regalis, and Craspedorrhynchus). Several key factors, at the island and individual levels, have emerged from these analyses that account for a large proportion of the variation in louse intensity across individuals. Host gender, host territorial status (or age), and degree of host inbreeding within an island explain most of the variation in louse intensity in a large multivariate analysis. The influence of host gender is explained by body size (females have higher louse intensities than males), birds without territories have higher louse intensities than territorial birds, and level of inbreeding in the host population is directly related to louse intensity. A path analysis demonstrates that indirect effects among these variables are also key in influencing louse intensity. Within the large marked hawk population residing on the island of Santiago, spatial, temporal and social dynamics of the host are studied in detail with respect to louse intensity. Host habitat, social group size, and length of host association with the breeding group (newcomers to social groups have higher intensities than those birds with longer associations) are important factors shaping louse intensity at the local level. Results of a louse removal experiment on adult hawk survivorship over a three-year period will also be presented.
On the sexual practices of animal lice (Phthiraptera).
Museum of Natural History of the Thuringian State Museum Heidecksburg, Schloßbezirk 1, D-07407 Rudolstadt, Germany. firstname.lastname@example.org
The mating behavior of animal lice remains very little studied. Observations of copulating animals are hardly possible under natural conditions. Most copulations, often accidentally discovered, have been observed during collection or in the artificial conditions of the laboratory. They have been described for all four of the suborders of the Phthiraptera and in a total of not less than 40 species. Apart from a few instances of facultative parthenogenesis (thelytoky), the Phthiraptera reproduce bisexually. Finding a partner in their relatively limited home range is a presumably random occurrence for the Rhynchophthirina, Ischnocera, and Anoplura. It is not known for certain whether chemical stimulation plays a role in this. In these groups, the mating act is preceded by an extremely brief, when recognizable at all, foreplay. In the Amblycera, males appear to actively search for females, even to chase them, a possible indication of an olfactory and/or visual sensory capacity. The copulatory initiative is always taken by the males, who waste no time if the female is willing. With some variants, two basic copulatory positions can be distinguished: suprafeminal (typical for Amblycera) and subfeminal (typical for Ischnocera, Anoplura, and Rhynchophthirina), though there are observations that throw some doubt on this simple picture. During copulation itself, the partners hold fast to the host integument (feather, hair, skin) using their legs and/or mandibles, and only the male additionally grasps the female with a leg pair (1st or 3rd) and/or the antennae. However there have been a few rarely observed cases of copulation in which the male only holds on to the female, so that she can even keep moving at the same time. Alongside simple genitals (solenoids), males have often evolved structurally very complex reproductive organs, whose outer part can be used to grasp the female while the phallic apparatus that lies inside is employed to transfer the semen directly into the vagina. The act of copulation can last between a few seconds and two days depending on species, but in no case does there appear to be an 'epilogue' of any kind. Some characters of secondary sexual dimorphism are functionally connected with copulation. This is well developed in body size, special antenna and leg structures, and abdominal plate patterns. Within the Phthiraptera, the copulatory position regarded as phylogenetically primitive, the suprafeminal (male lies with underside on the back of the female) has been retained in this unmodified form by only a few groups, even in the Amblycera.
Indirect measures of sexual selection in avian lice.
Lajos Rózsa1 & Andrea Harnos2
1 Animal Ecology Research Group, Hungarian Academy of Sciences - Hungarian Natural History Museum, Budapest, Ludovika 2, H-1083 Hungary.
2 Szent István Univ, Fac Vet Sci, Dept Biomath & Informat, Istvan 2, Budapest, H-1078 Hungary.
Sexual size dimorphism (SSD) is often treated as an indirect measure of sexual selection: in case of sperm competition, larger males perform better than smaller ones. Lice live in subpopulations separated on different host individuals, less isolated subpopulations are subjected to heavier sexual selection and thus have relatively larger males. In avian lice, conventional wisdom says that large-bodied species appear to have relatively larger males (as compared to females). This may have 2 explanations. First, larger parasites living on larger hosts may exhibit greater prevalence, second, larger-bodied parasites may have better transmission capabilities. Prevalence data gathered from the literature provides some support for the hypothesis that prevalence increases with body size in Menoponid and Philopterid lice, but not in Ricinids, where a non-significant negative relationship arises.
In the present study, we used host body size (HBS) and relative louse body size (RLBS: residuals from the log-host-size/log-louse-size regression) as independent variables. Length dimorphism (LD: residuals from the log-female-length/log-male-length regression) and head width dimorphism (HWD: calculated similarly) were used as dependent variables. We gathered total body length and head width measures of >1500 species and populations from the literature. Treating characters of species as independent measures, both HBS and RLBS covaried positively with LD and HWD of Menoponids and Philopterids. In Ricinids, on the other hand, there was a negative relationship between HBS and LD, and a positive between RLBS and LD. Some of these correlations disappear after controlling for phylogenetic effects, however, the positive relationship between RLBS and HWD Menoponids and Philopterids, and between RLBS and LD in Ricinids still remains robust.
Briefly, SSD of avian lice covaries with body size measures, apparently in accordance with levels of transmission capabilities and thus levels of outbreeding, as predicted evolutionary hypotheses. Sexual selection seems to be an effective agent of morphological evolution in lice.
Host defense facilitates the coexistence of competing lice species.
Sarah E. Bush1,2, Jael R. Malenke1, Dale H. Clayton1
1 Dept of Biology, Univ of Utah, Salt Lake City, UT 84112, USA.
2 Present Address: Natural History Museum, Univ of Kansas, Lawrence, KS 66045, USA.
Interspecific competition is a major force governing the structure of ecological communities. However, relatively little is known about the importance of interspecific competition in parasite communities. We approach this topic empirically, using a pigeon-louse model system. Rock Pigeons (Columba livia) are commonly parasitized by two different types of feather lice (Ischnocera) known as “wing” lice and “body” lice. To test for interspecific competition between wing and body lice, we experimentally manipulated populations of these two species on captive Rock Pigeons. Birds were infested with only wing lice, only body lice, or both species of lice. To determine whether host defense impacts competition between feather lice we also manipulated preening, the birds' principle mechanism of ectoparasite defense. We measured louse population size and resource use over the course of ten louse generations. We found that both types of lice eat the same feather resources, that competition for these resources occurs, and that this competition is asymmetric, with body lice outcompeting wing lice. We found that host defense, preening, mediates competition by maintaining small louse populations. To explore the consequence of the competitive effect of body lice on wing lice, we examined populations of these lice on 150 free ranging Rock Pigeons under natural conditions. We found that as body louse populations increase, wing louse populations decrease to the point of local extinction. Competition therefore appears to play an important role structuring the composition of louse communities.
Comparative transmission dynamics of ecological replicates: Experiments with columbiform body and wing lice.
Christopher W. Harbison, Sarah E. Bush, Jael R. Malenke & Dale H. Clayton
Dept of Biology, Univ of Utah, 257 South 1400 East, Salt Lake City, UT, 84112, U.S.A.
Transmission to new hosts is an essential feature of parasite ecology and is central in influencing gene flow, population genetic structure and host specificity. Despite the importance of transmission dynamics, few studies have empirically tested its influence on host-parasite interactions. Columbiformes (pigeons and doves) are host to two common types of feather specialist lice: “body” lice and “wing” lice. Interestingly, while body lice and wing lice are ecologically similar, body lice consistently have more population genetic structure and are more host specific than wing lice. Using a Rock Pigeon (Columba livia) model system, we compare body louse and wing louse transmission to better understand the interaction between transmission dynamics and host-parasite coevolution. While we found no difference in the rate of body louse and wing louse transmission via the direct contact of hosts, wing lice also used an indirect transmission mode: phoresis on Hippoboscid flies. Additionally, phoresis led to host-switching events in wing lice, which is a key factor in determining parasite host specificity, and ultimately, the degree of cospeciation with their hosts. We argue that this difference in transmission dynamics has led to differences in the population genetic structure and host specificity of body lice and wing lice.
Evolution of cryptic coloration in host-specific lice.
Dukgun Kim, Michelle Reed, Sarah E. Bush & Dale H. Clayton
Dept of Biology, Univ of Utah, Salt Lake City, Utah, U.S.A.
Cryptic coloration is a common adaptation to avoid detection by predators and is widespread among free ranging insects. Ectoparasites may also use cryptic coloration to avoid host defense, but this hypothesis has never been tested. Host-specific lice often match the color of their hosts, which may help them avoid host defense. We conducted a study to investigate whether cryptic coloration has evolved in lice. First, using microscope slide mounted “body” lice, we show that lice on lightly colored birds are lighter in color than congeneric lice on darkly colored birds. Interestingly, this pattern did not hold for “head” lice that live only regions that birds do not see or preen (head and upper neck). We compared the survival of identical numbers of lice put on white, black, and wild type pigeons. We also painted lice to test whether birds preen them off more when the lice no longer match plumage color. We present the results of these experiments and discuss their implications.
Local adaptation differentiates haplotypes of a feather-feeding louse: Incipient speciation?
Jael R. Malenke1, Kevin P. Johnson2 & Dale H. Clayton1
1 Dept of Biology, Univ of Utah, Salt Lake City, Utah, USA.
2 Illinois Natural History Survey, Champaign, Illinois, USA.
Differential niche use has long been associated with species diversity. Yet, the adaptive significance of niche use to the process of speciation is not well known. Feather lice (Phthiraptera: Ischnocera) and their avian hosts present a good system with which to examine speciation in progress because host use clearly defines louse niche. Columbicola macrourae is an unusually generalist louse species found on 14 different species of Columbiform host species. We used the mitochondrial CO1 gene to reveal at least 4 widely divergent molecular haplotypes within C. macrourae. The individual haplotypes show some degree of host specificity, each haplotype being found on only one or a few of the many possible hosts. In a reciprocal transfer experiment, we found a fitness advantage to haplotypes on their native hosts compared to a novel host. We re-examined C. macrourae morphology using factor analyses and found differences in haplotype size that are positively correlated with host size. The size correlation between haplotype and host is consistent with the relationship previously shown to exist across the entire louse genus, suggesting size is important to understanding the adaptive role of host use. This may be because these lice escape host defense (preening) by inserting their long, thin bodies in the trough between feather barbs. A close fit between louse size and interbarb space (which covaries with host size) is necessary for louse survival. Differential host use, in this system, is advantageous to the native louse haplotypes, creating independent evolutionary trajectories and resulting in possible future speciation events.
The Diversification of Lice: Origins
Kevin P. Johnson1, Kazunori Yoshizawa2 & Vincent S. Smith3
1 Illinois Natural History Survey, Champaign-Urbana, U.S.A.
2 Hokkaido Univ, Sapporo, Japan.
3 The Natural History Museum, London, UK.
Historically parasitic lice have been classified into one (Phthiraptera) or two (Mallophaga and Anoplura) insect orders. Considerable morphological and molecular evidence suggest that sucking lice (Anoplura) are derived from chewing lice, and are the sister taxon of the suborder Rhynchophthirina. In addition, it is now widely accepted that parasitic lice are derived from within the bark lice (Psocoptera), making the insect order Psocoptera paraphyletic. The monophyly of parasitic lice has rarely been questioned, and until recently has not been rigorously tested. Recent evidence from nuclear 18S rDNA sequences suggest that parasitic lice are derived twice independently from within the Psocoptera, with the suborder Amblycera being the sister taxon of the bark louse family Liposcelididae, and separated from the other three suborders of parasitic lice. These results are partially corroborated by a recent study of the male genitalia of bark lice and parasitic lice. Sequences of other genes are less decisive, but no gene recovers a monophyletic Phthiraptera when relevant taxa are included. These results indicate that parasitism evolved twice within the Psocodea (Psocoptera + Phthiraptera), but needs to be tested with additional data.
The Diversification of Lice: Age.
Vincent S. Smith1, Tom Ford2, Kevin P. Johnson3, Paul Johnson4, Kazunori Yoshizawa5 & Roderic D. M. Page4
1 The Natural History Museum, London, UK.
2 Imperial College, London, UK.
3 Illinois Natural History Survey, Champaign-Urbana, U.S.A.
4 Univ of Glasgow, Scotland, UK.
5 Hokkaido Univ, Sapporo, Japan.
Until recently the debate over the age of Phthiraptera has been a matter of speculation based on their present day distribution, and the antiquity of the host groups they parasitize. The discovery of two new fossils, coupled with recent phylogenetic work and advances in the field of molecular dating now make it possible to address this question within a scientific framework. Using multiple calibration points we examine the temporal congruence between host and parasite phylogenies to show that the origin of crown group lice (Insecta: Phthiraptera) significantly predates the tertiary radiation of crown group mammals and birds predicted from the host fossil record. These data favor a Cretaceous diversification of parasitic lice approximately 100 million years ago. Since lice are permanent obligate ectoparasites that are dependant upon their hosts, these data imply a contemporaneous Cretaceous diversification of host lineages. Unequivocally establishing the ancestral host for parasitic lice (i.e. mammals or birds) is not possible with the available data. However, examination of the intra-subordinal divergence dates within these clades strongly points toward a phthirapteran ancestry on the lineage leading to modern birds.
The Diversification of Lice: Phylogeny.
Vincent S. Smith1 & Kevin P. Johnson2
1 The Natural History Museum, London, UK.
2 Illinois Natural History Survey, Champaign-Urbana, USA.
In just ten years our understanding of phthirapteran relationships has progressed from an informal conspectus of the major louse lineages, to more than 40 independent evolutionary trees, which collectively represent information on the phylogeny of almost eighty percent of all louse genera. These studies form the framework upon which advances in our understanding of louse biology are built. In this talk we focus on recent progress toward building a complete “tree-of-lice”. Notably two (near complete) generic level phylogenies for Ischnocera and Anoplura. We discuss the cophylogenetic implications of these trees, highlight areas of phylogenetic uncertainty, and with examples, discuss the utility of morphological and molecular data at resolving phthirapteran relationships at both macro- and micro-evolutionary scales.
The Diversification of Lice: Specialization.
Kevin P. Johnson1 & Vincent S. Smith2
1 Illinois Natural History Survey, Champaign-Urbana, U.S.A.
2 The Natural History Museum, London, UK.
The phthirapteran suborder Ischnocera accounts for over 60% of all louse species, and of these more than 90% parasitize birds. One explanation of this diversity is the niche specialization exhibited by many of these taxa. Lice specialized to different microhabitats have distinct morphologies with most categorized as 'wing', 'body', or 'head' specialists. Since many birds host multiple microhabitat specialists, this niche specialization may account for the large number of ischnoceran species. Two processes may have given rise to this diversification: Body form assortment, in which the microhabitat specializations evolved early in the radiation of Ischnocera and these specialists radiated with birds; or repeated character displacement, in which the different microhabitat specialists evolved repeatedly on different bird lineages. These two hypotheses can be tested with a phylogeny for avian Ischnocera. Using competing molecular and morphological phylogenies for lice, we show that repeated instances of character displacement have occurred throughout the Ischnocera and that morphological character convergence caused by niche specialization has obscured the true phylogenetic relationships in some cases. However, the overall picture is mixed with some evidence for body form assortment.
The fossilization and discovery of Megamenopon rasnitsyni the first fossil louse.
Herbert Lutz1, Torsten Wappler2 & Robert C. Dalgleish3
1 Naturhistorisches Museum Mainz, Landessammlung fr Naturkunde Rheinland-Pfalz, Mainz, Germany
2 Institute of Paleontology, University Bonn. Nussallee 8, 53115 Bonn
3 10601-G Tierrasanta Blvd., #110, San Diego, CA, U.S.A.
Megamenopon rasnitsyni Wappler, Smith, Dalgleish, 2003 (Amblycera: Menoponidae) is the first fossil phthirapteran (Dalgleish, Smith, Palma, Price, 2006). Its discovery in the oil shale of Eckfeld Maar is a consequence of unique taphonomics and of the thoroughness of the investigation of the fossil insects embedded in this stratigraphy. Taphonomics or the process of fossilization is complex though relatively well known within this site. During the Middle Eocene (44mya) the pond attracted or held a variety of fish, insects, birds, mammals and a great diversity of microorganisms. Upon death these organisms as they slowly drifted towards the bottom were frequently caught in upward circulation within the water column and subject to decomposition and mineral replacement at or near the cellular level.
Megamenopon rasnitsyni, as the generic name suggests is noteworthy in its size. It is more than twice the size of similar extant lice, but still it is only 6.74 mm in total length. The process of fossilization within the Maar is such that even the minute sculpturing of the exoskeletons of some hymenoptera and coleoptera reflect the colors or irridescence seen in their extant relatives. The setae and feather barbules within the gut are even discernible in the fossil of M. rasnitsyni. Extant genera of menopids similar to Megamenopon are known primarily from birds that frequent aquatic environments. Thus the louse is presumed to be off such a host. There are many possible hosts, including those represented in the fossil birds recovered from Eckfeld Maar, however the louse was not found in association with any other organism. What is known of the biology of chewing lice suggests that menoponids are more likely to abandon a dead or dying bird than would a philopterid. Thus it is entirely possible that the louse left the bird and died independently of its host. If a fossil feather is found with a louse attached that louse is most likely to be a philopterid, for they typically do not abandon the dying host.
Mitochondrial genomics of lice and their relatives.
S. L Cameron1. C. Covacin2, Kevin P. Johnson3 & M. F. Whiting1
1 Dept of Integrative Biology, Brigham Young Univ, Provo, UT, 84602, USA.
2 School of Molecular & Microbial Sciences, Univ of Queensland, St. Lucia, QLD, 4072, Australia.
3 Illinois Natural History Survey, Champaign, IL, 61820, USA.
Compared to most insects whose mitochondrial genome arrangements are extremely conserved, the Psocodea (lice and relatives) have the highest rates of genome rearrangement amongst insects and one of the highest of any animal group. This diversity of genome arrangements within a relatively small clade (approx. 10'000 described species) makes lice a perfect system in which to examine the evolution of genome rearrangements, the factors which predispose genomes to rearrange and their utility in systematic studies. The free-living relatives of lice, the Psocoptera (sensu lato) have fewer rearrangements than the louse groups once classified as Phthiraptera. The largest suborder Psocomorpha is defined by a major rearrangement of protein coding genes and a minor rearrangement of tranfer RNA genes. Trogiomorpha has a range of rearrangements from early diverging members with the groundplan arrangement to derived members with multiple major and minor rearrangements. The Nanopsocetae (including the parasitic louse groups) have extreme rates of genome rearrangements and the utility of genome architecture in resolving this phylogenetically intractable set of taxa will be discussed.
Micro- and macroevolutionary perspectives into the cophylogenetic history of toucans and their chewing lice.
Jason D. Weckstein1, John M. Bates1 & Alexandre Aleixo2
1 Zoology Dept, The Field Museum, Chicago, IL, U.S.A.
2 Museu Paraense Emilío Goeldi, Belém, Brazil.
Cophylogenetic studies of hosts and permanent ectoparasites provide a unique opportunity to reconstruct the history and environmental context in which the processes of diversification and speciation occur. Permanent ectoparasites share a common evolutionary history with their hosts, and one can reconstruct this macroevolutionary history by superimposing a parasite's phylogeny onto the host's phylogeny. Analyses of both mitochondrial and nuclear DNA sequences from Ramphastos toucans and their ectoparasitic Austrophilopterus chewing lice show little or no cospeciation in their cophylogenetic history. Secondly, monophyletic louse lineages are not necessarily restricted to monophyletic host lineages. Instead, closely related Austrophilopterus lice are found on more distantly related but sympatric toucan hosts and geography has significant phylogenetic signal on the louse phylogeny. A number of features of the host (e.g., hole nesting) and parasite (e.g., phoresis) life histories might promote these patterns of host-switching or dispersal between syntopic host species. In this talk, we will examine patterns of population genetic structure, phylogeographic structure, and gene flow in Austrophilopterus chewing lice to understand the underlying microevolutionary forces shaping the associations and cophylogenetic history with their toucan hosts. The addition of a microevolutionary approach can broaden our perspective on these events, because population genetic structure and processes such as dispersal are important factors underlying coevolutionary history. Thus, our understanding of macroevolutionary events such as host-switching will be illuminated by data on microevolutionary processes.
Louse population genetics as a tool for understanding the individual and population histories of their hosts.
Noah K. Whiteman1, Rebecca T. Kimball2 & Patricia G. Parker1
1Univ of Missouri-St. Louis, U.S.A.
2Univ of Florida-Gainesville, U.S.A.
Many vertebrate species have suffered population bottlenecks that obscure phylogeographic and population genetic inference. In several instances, the genetics of directly transmitted microbes of vertebrates have been successfully used to trace their host's recent evolutionary history and understand contemporary relationships among host populations. Here, we show that the population genetics of a host-specific, obligate and vertically transmitted feather louse (Degeereilla regalis) parasitic on an endemic Galápagos bird (Buteo galapagoensis), could be used to help understand its host's recent population histories in the Galápagos Islands. Louse mtDNA was a superior marker in several respects relative to host DNA. Twenty mtDNA lineages were recovered within D. regalis island populations that were highly genetically differentiated (FST = 0.90) and 85% (17/20) of these lineages were restricted to a single island population. Comparatively, B. galapagoensis was invariant at the same mtDNA regions (FST = 0) and although some variation was found in other mitochondrial regions, only 57% (4/7) of these haplotypes were restricted to a single island. Results of an assignment test revealed that all louse individuals sampled on six of the eight islands were correctly assigned back to their island of origin using their mtDNA haplotypes, whereas in the host, all individuals were correctly assigned back to their island of origin in 4/8 islands using minisatellites, and fewer still using host mtDNA haplotypes. Whereas 89% of interisland FST comparisons were statistically significant for the parasite (using mtDNA), fewer comparisons were significant for the host at either mtDNA (82%) or nuclear minisatellites (75%). Moreover, the evolutionary relationships among four island populations of B. galapagoensis, previously obscured by the founder event, were revealed by the parasite's genealogy. Similarly, a previously undocumented inter-island migration event of D. regalis (and its host) long after the divergence of the two populations of interest was detected using both assignment tests and coalescent simulations, demonstrating that individual as well as population histories of hosts could be studied using the genetic signal in their louse populations. Employing D. regalis genetics as an inferential tool was validated by demonstrating that: (1) the inter-island pattern of parasite population subdivision was significantly related to the host's; (2) coalescent-based inter-island migration rate estimates were significantly related to that of the host and island population divergence times of D. regalis were each dependent on geographic distance between islands, also consistent with the host's pattern of isolation by distance; (3) parasite effective population sizes on each island were positively related to host population size (or nuclear genetic diversity), linking parasite population demography to the host's. This study serves as a model for using parasites to infer the recent evolutionary histories of their hosts.
Phylogeny, cophylogeny, and molecular rate comparisons of Fahrenholzia sucking lice (Phthiraptera: Anoplura) and their Heteromyid hosts (Rodentia: Heteromyidae).
Jessica E. Light & Mark. S. Hafner
Museum of Natural Science, Louisiana State Univ, U.S.A.
In this study, mitochondrial and nuclear DNA sequence data were used to reconstruct phylogenetic relationships for 11 of the 12 currently recognized species of Fahrenholzia, which are found only on rodents of the family Heteromyidae. Phylogenetic analyses the mitochondrial and nuclear datasets were in general agreement, resulting in a well resolved Fahrenholzia phylogeny. Analyses supported monophyly of lice parasitizing the host subfamily Heteromyinae (spiny pocket mice), and lice parasitizing the genera Chaetodipus (pocket mice) and Perognathus (silky pocket mice) each represent monophyletic lineages. Phylogenetic patterns and levels of genetic differentiation suggest that F. microcephala, F. pinnata, and F. reducta may contain cryptic species. Historical associations between heteromyid rodents and their sucking lice were determined using tree-based, distance-based, and data-based methods of cophylogenetic analysis. Tree-based and distance-based methods revealed a significant pattern of cophylogeny between Fahrenholzia lice and their hosts, and results from data-based methods indicated that differences between host and parasite phylogenies were the result of historical events such as host switching or extinction. Comparison of rates of nucleotide substitution at 4-fold degenerate sites in the COI gene revealed that Fahrenholzia lice are evolving roughly 60% faster than their heteromyid hosts. Recent comparisons of molecular rates between pocket gophers and chewing lice revealed that their disparate rates of evolution are likely the result of population-level phenomena, such as effective population size and frequency and severity of founder events and drift. It is likely that population-level phenomena are also the cause of the rate differences observed between heteromyid rodents and their parasitic sucking lice.
Host-parasite associations, geography and population subdivision in Polyplax serrata (Anoplura: Polyplacidae) and wood mice of genus Apodemus.
J. _tefka1, V. Hyp_a1, J. Fri_ová2 & M. Stanko2
1 Faculty of Biological Sciences, Univ of South Bohemia and Biology Centre ASCR, Institute of Parasitology, Brani_ovská 31, 37005 _eské Bud_jovice, Czech Republic.
2 Dept of Vertebrate Ecology, Institute of Zoology, Löfflerova 10, SK-04001 Kosice, Slovak Republic.
The origin and maintenance of host specificity belong to the long debated topics of parasite evolution. Many examples of long-term coevolution between hosts and their parasites at a higher (i.e. interspecific) evolutionary level have been described and various methodologies developed for their reconstruction . However, the observations on a host-mediated population structure and the speciation processes in parasites are scarce. Here we present an example of host-dependent structuring in populations of a louse Polyplax serrata, a common Holarctic species parasitising a broad spectrum of mice of the genus Apodemus. Altogether, we sampled and analyzed 105 P. serrata isolates from 4 species of Apodemus mice in central Europe from localities across a span of 600 km, and from two distant localities, one in Great Britain and the other in south Siberia. Molecular analysis using 381 bp long sequences of Cytochrome Oxidase I gene (COI) revealed an existence of several host- and geography- specific lineages. The basic phylogenetic topology was inferred in PAUP by Maximum Parsimony with the related species P. spinulosa and Hoplopleura acanthopus as outgroups. Four distinct P. serrata clades were recognized. One of them was specific for a distant Siberian locality represented by the lice sampled from A. peninsulae. Of the three European clades, one is specific for A. agrarius isolates, another for A. flavicollis isolates, and the last one is comprised of a mixture of lice originating from two different species, A. sylvaticus and A. flavicollis. Further host-related substructuring in European clades was revealed by constructing genetic networks of haplotypes (TCS). The results show that the genetic structure of the lice population(s) is determined by their affiliation and shared evolutionary history with different host taxa rather than geographic isolation.
Taxonomic problem of Gyropus parvus (Ewing 1924) (Gyropidae, Amblycera) parasite of Ctenomys (Rodentia, Ctenomyidae).
N. S. Martino1, Romero, M. D.2, Sánchez Sánchez, G.R. 1 & Delores del C. Castro1
1 Facultad de Ciencias Naturales y Museo de La Plata, calle 64 Nº 3, Laboratorio Zoología General, CP1900, La Plata, Buenos Aires, Argentina. email@example.com
2 Area Mastozoología. Museo Municipal de Ciencias Naturales Lorenzo Scaglia. Av. Libertad 3099 CP 7600. Mar del Plata., Buenos Aires, Argentina.
Taxonomic and nomenclatural history of Gyropus parvus parasite of the fosorial rodent Ctenomys known as tuco-tuco is analysed. The studied taxon was first described by Ewing in 1924 as Monogyropus parvus. Subsequently, Werneck in 1936 carried out new contributions to male description. The same author described female adult stage in 1948. Castro, Cicchino & Torres-Mura in 1987 worked on a comparative and descriptive study of Gyropus parvus as parasites of octodontid rodents. Description of external chorionic egg morphology of Gyropus parvus was contributed by Cicchino and Castro in 1994. The different sources of studied specimens and the fragmentary registers, recorded in the different contributions to the taxon biology, suggest the need to unify all the information obtained up to date. Due to the difficult access to type material and with the purpose of getting reference specimens from the Gyropus parvus type locality, samples of Ctenomys rodents, host of the taxon in study, were taken from Estancia Huanuluán, Rio Negro, Argentina, according to the original description. The obtained lice were studied with conventional light microscopy, drawn with a camera lucida, photographed with a digital camera, and observed with a scanning electronic microscope (SEM). The material was preserved in: permanent slides, processed samples for SEM study, and reference material preserved in 70% ethanol solution. Life cycle stages were described for the collected samples of Gyropus. Host taxonomic situation was analysed. The variability observed in morphologic characters of the collected lice was discussed with the current descriptions. The obstacles observed from the comparison between original description and the studied specimens taken from type locality were analyzed. In the present contribution, differences related to the size of collected samples and the use of new sampling techniques with the execution of sampling protocols for ectoparasite populations were taken into account. In conclusion, the use of provisional open nomenclature, until the observations of type material will be included in our study, Phthiraptera specimens from Huanuluan were determined as Gyropus cf.parvus. Here, we discussed the possibility of establishing as Gyropus parvus topotypic specimens, the collected lice in the type locality, Huanuluán, previous study of the type material.
Pair of lice lost: parasites as markers of primate evolutionary history.
David L. Reed, Jessica E. Light & Julie Allen
Florida Museum of Natural History, Univ of Florida, USA.
In this study, phylogenetic relationships of primate sucking lice were determined using multiple mitochondrial and nuclear markers. These trees were thoroughly analyzed individually and combined using a variety of phylogenetic techniques. Louse trees were compared to known host trees using tree-based and data-based methods of cophylogenetic analysis. These analyses revealed significant cospeciation between primate lice and their hosts although there were several instances of host switches and parasite extinctions, which have shed light on interesting contrasts among methods of cophylogenetic inference. In the presence of cospeciation, relative rates of evolution between primate lice and their hosts were estimated and data from the primate fossil record were used to determine how long these distantly related organisms have been associated.
Parasitic lice as markers of human evolutionary history.
David L. Reed, Jessica E. Light, Julie Allen, Tamar Carter & Lauren Long
Florida Museum of Natural History, Univ of Florida, USA.
The human head/body louse (Pediculus humanus) has been shown to be a useful marker of human evolutionary history. For example, its closest living relative is found on chimpanzee, and the chimp and human lice diverged roughly 6 million years ago. P. humanus even shows evidence of a recent population expansion roughly 100,000 years ago matching the out-of-Africa expansion of its host. This begs the question, “can these lice be used to study very recent events in human evolutionary history, such as human migrations?” To date, all studies have utitlized only a few individual lice per locality, and variation inherent in a large population remains unsampled. Herein, we have sampled sites more thoroughly in an attempt to calculate precise frequency of the distinctly different haplotypes described by previous researchers. The haplotype described by Reed et al. 2004 as the New World haplotype is found in very high frequency among our samples collected throughout the New World. However, as other researchers have pointed out, the haplotype is clearly not restricted to the New World, and what remains is to assess its abundance elsewhere around the world. In fact, we propose that few answers regarding human evolutionary history will come from lice until we take a page from the book of molecular anthropologists and begin a cooperative sampling strategy that is sufficient for the questions we wish to address. In our work, we are focused on questions relating to the peopling of the Americas. From both recent and ancient DNA sequence data we explore the use of haplotype frequency information from human lice to determine the route, timing, and origin of the peopling of the Americas.
Genetic analyses of human lice: implications for human evolution.
Max Planck Institute for Evolutionary Anthropology, Deutscher Platz 6, D-04103 Leipzig, Germany.
Human lice are obligate parasites of humans, therefore the spread of lice around the world was accomplished by human migrations. Hence, analyses of molecular genetic variation in lice should provide independent insights into human migrations. However, human lice can provide potentially even more interesting insights into human evolution, since humans are parasitized by three types of lice, which may in turn reflect particular events in human evolution. Human head and body lice are distinguished primarily by their ecology: head lice live and feed on the scalp, while body lice feed on the body but live in clothing. This difference presumably arose when clothing became available as an ecological niche, and in previous work we estimated that head and body lice diverged 40,000-100,000 years ago; hence, by inference, this is when clothing became important (Kittler et al., Current Biology 13:1414-1417, 2003). We are currently analyzing genetic variation in pubic lice, which are restricted to the pubic region, and thus may have colonized humans after humans lost body hair. Analyses of human parasites can thus provide novel insights into human evolution.
Updated 25 September, 2006