@article {68969, title = {Interspecific differences in AETHIA SPP. auklet odorants and evidence for chemical defence against ectoparasites}, journal = {Journal of Chemical Ecology}, volume = {30}, year = {2004}, month = {10/2004}, pages = {1921-1935}, abstract = {

Abstract\—The true auklets (Genus Aethia) are small planktivorous seabirds of the Bering Sea and North Pacific. Two species, the crested and whiskered auklets produce volatile citrus-like odorants. We here show that the whiskered auklet odorant is composed predominantly of two odd-numbered aldehydes (heptanal and nonanal) with no detectable unsaturated aldehydes. By comparison the crested auklet odorant is dominated by even-numbered aldehydes, both saturated and monounsaturated, ranging in size from 6 to 12 carbons. This is evidence of species-specific acquisition or biosynthetic pathways. We clarify the chemistry of the crested auklet odorant. We cite evidence that the C-12:1 aldehyde in crested auklets is actually two isomers, (Z)-4-dodecenal and (Z)-6-dodecenal. We also report on experimental evidence that aldehyde constituents kill and repel ectoparasites. Efficacy of the aldehydes may increase when they are combined in a mixture. The repellency of the mixture increases with chemical concentration. This suggests that individuals with higher chemical production are likely to repel ectoparasites more effectively.

}, keywords = {(Z)-4-dodecenal, (Z)-6-dodecenal, Aldehydes, chemical defence, Crested auklet, ectoparasites, pheromones, seabirds, synthesis, whiskered auklet}, url = {http://phthiraptera.info/sites/phthiraptera.info/files/68969.pdf}, author = {Hector D. Douglas_III and Jason E. Co and Tappey H. Jones and William E. Conner} } @article {68968, title = {Measurement of Chemical Emissions in Crested Auklets (Aethia cristatella)}, journal = {Journal of Chemical Ecology}, volume = {32}, year = {2006}, month = {Mar-11-2007}, pages = {2559 - 2567}, abstract = {

Abstract This report presents the first quantitative estimates of emission rates for chemical signals in a bird\—the crested auklet (Aethia cristatella). Volatile emissions from live birds were captured in a purified airstream onto polymer traps. Traps were eluted with methanol and analyzed with gas chromatography-mass spectrometry. The volatile collection chamber was field-calibrated with an in-line bubbler and synthetic octanal, the dominant constituent of the crested auklet\’s citruslike odor. The result is an index of volatile chemical emissions within a small population of wild crested auklets at Big Koniuji Island, AK, USA. The average emission rate for octanal was 5.7 \μl/50 min. Males and females did not differ in their emission rates (t(0.05)two-tailed = 0.44, P = 0.66). There was a sevenfold difference between minimum and maximum emission rates. Prevalence of tick infection (2\%) was low despite the high abundance of ticks in the colony. The crested auklet with the lowest chemical emission rate was heavily parasitized by ticks.

}, keywords = {chemical defines, chemical emissions, chemical signal, Crested auklet, ectoparasites, octantal, repellents}, issn = {0098-0331}, doi = {10.1007/s10886-006-9164-2}, url = {http://link.springer.com/10.1007/s10886-006-9164-2}, author = {Hector D. Douglas_III} } @article {68967, title = {An Extraordinary Host-Specific Sex Ratio in an Avian Louse (Phthiraptera: Insecta){\textemdash}Chemical Distortion?}, journal = {Environmental Entomology}, volume = {44}, year = {2015}, month = {Sep-15-20152017}, pages = {1149 - 1154}, abstract = {

ABSTRACT Distortions of sex ratios and sexual traits from synthetic chemicals have been well documented; however, there is little evidence for such phenomena associated with naturally occurring chemical exposures. We reasoned that chemical secretions of vertebrates could contribute to skewed sex ratios in ectoparasitic insects due to differences in susceptibility among the sexes. For example, among ectoparasitic lice the female is generally the larger sex. Smaller males may be more susceptible to chemi- cal effects. We studied sex ratios of lice on two sympatric species of colonial seabirds. Crested auklets (Aethia cristatella) secrete a strong smelling citrus-like odorant composed of aldehydes while a closely re- lated congener the least auklet (Aethia pusilla) lacks these compounds. Each auklet hosts three species of lice, two of which are shared in common. We found that the sex ratio of one louse species, Quadraceps aethereus (Giebel), was highly skewed on crested auklets 1:69 (males: females), yet close to unity on least auklets (1:0.97). We suggest that a host-specific effect contributes to this difference, such as the crested auklet\’s chemical odorant.

}, keywords = {aldehyde, lice, seabird, Sex ratio distortion}, issn = {0046-225X}, doi = {10.1093/ee/nvv073}, url = {http://ee.oxfordjournals.org/lookup/doi/10.1093/ee/nvv073}, author = {Hector D. Douglas_III and Jael R. Malenke} } @article {61691, title = {Colonial seabird{\textquoteright}s paralytic perfume slows lice down: An opportunity for parasite-mediated selection?}, journal = {International Journal for Parasitology}, volume = {43}, year = {2013}, month = {4/2013}, pages = {399 - 407}, abstract = {

Selection for chemical signals in birds could be influenced by parasitism as has been previously suggested for visual and acoustic displays. Crested auklets (Aethia cristatella), colonial seabirds from Alaska and Siberia, offer an example of how this might occur. Crested auklets secrete lipids in plumage, possibly as an indicator of status and attractiveness. Prominent among these secretions are aldehydes, which are noticeable as a pungent citrus-like odour. Octanal and hexanal, the most abundant aldehydes in the plumage of crested auklets, are potent invertebrate repellents, reported from the chemical defenses of heteropteran insects. These aldehydes occur at high concentrations within specialized secretory struc- tures. Experiments presented here show that these compounds can paralyse lice. Lice obtained from auk- lets were paralysed or killed within seconds after exposure to volatiles from nicks in the integument of a crested auklet. Chemical analysis demonstrated the presence of aldehydes in the area of integument used for this experiment. Lice exposed to control tissues in the same manner were not affected. A synthetic blend of crested auklet odourant constituents caused a sequence of impaired behaviours in auklet lice comparable to the effects of neuroactive insecticides. The time until onset of effects was dependent on dose, suggesting that the rate of molecular diffusion into louse spiracles was the explanatory factor. Impairment was evident even at very low concentrations that can occur in crested auklet plumage during winter. The same aqueous emulsions were present in both experimental and control treatments but lice in controls experiments were not affected. Crested auklets inhabit crowded social neighbourhoods with larger social groups, closer interindividual spacing and higher rates of contact than sympatric least auk- lets (Aethia pusilla). This could help to explain why crested auklets can have higher louse abundances. Lice are spread through direct contact between hosts and louse-infected mates could transmit lice to off- spring. Large differences in the louse loads on crested auklet fledglings suggest differences in the parental transmission of lice to offspring.

}, keywords = {Aldehydes, chemical defence, Chemical ecology, Crested auklet, lice, parasite-mediated selection, sociality}, issn = {00207519}, doi = {10.1016/j.ijpara.2013.01.004}, url = {http://phthiraptera.info/sites/phthiraptera.info/files/61691.pdf}, author = {Hector D. Douglas_III} } @article {45755, title = {Is the citrus-like plumage odorant of Crested Auklets (Aethia cristatella) a defense against lice?}, journal = {Journal of Ornithology}, volume = {146}, year = {2005}, month = {2005}, pages = {111 - 115}, abstract = {

Abstract Plumage odors may function as chemical defenses against ectoparasites in birds. We tested this hypothesis for crested auklets (Aethia cristatella), a species of colonial seabird that emits a very strong citrus- like odor from its plumage. This odorant contains known chemical repellents. We evaluated evidence for chemical defense in this species using two approaches. First, we exposed pigeon lice to the volatiles emitted by freshly plucked plumage and by whole specimens. Louse survi- vorship was compared between these treatments and two controls. Second, we compared louse abundance on crested auklets versus a closely related congener that nests in close association. Louse survivorship did not differ between crested auklet treatments and controls. Comparison of ectoparasite loads showed that crested auklets had significantly higher louse abundance than least auklets (A. pusilla), even after controlling for body size. Our results failed to support two expectations for chemical defense. Presence of the crested auklet plumage odorant in our experiments did not reduce louse life span. Presence of the aldehyde odorant in nature did not reduce louse abundance on crested auklets. Hence we conclude that the aldehyde odorant is not immediately lethal to lice at natural concentrations in plumage.

}, keywords = {aves, avian plumage doors, bird, chemical defence, Chewing lice, Crested auklet, defense, ectoparasite load}, doi = {0.1007/s10336-004-0065-2}, url = {http://www.phthiraptera.info/sites/phthiraptera.info/files/44482.pdf}, author = {Hector D. Douglas_III and Jael R. Malenke and Clayton,Dale H.} } @article {45125, title = {Heteropteran chemical repellents identified in the citrus odor of a seabird (crested auklet: Aethia cristatella): evolutionary convergence in chemical ecology}, journal = {Naturwissenschaften}, volume = {88}, year = {2001}, month = {2001}, pages = {330-332}, abstract = {

The exogenous application of chemical repellents is widespread in birds, but endogenous production is exceedingly rare. We herein report a new class of avian defensive compounds isolated from the feathers and volatile odor of the crested auklet (Aethia cristatella). Mass spectra indicate that n-hexanal, n-octanal, n-decanal, Z-4-decenal and a 12-carbon unsaturated aldehyde comprise the auklet odorant. Octanal and hexanal are also secreted in the repugnant metasternal gland emissions of heteropteran insects and are known to be potent invertebrate repellents. We suggest that the auklet odorant functions as an ectoparasite repellent and a signal of mate quality. This would represent a rare and direct link between vigor, quality and parasite resistance, one of several putative bases for mate selection. This is the first report of defensive compounds produced by a seabird or colonial bird and one of the few examples of chemical defense in a polar or subpolar marine vertebrate.

}, doi = {DOI: 10.1007/s001140100236}, url = {https://www.academia.edu/9182137/Heteropteran_chemical_repellents_identified_in_the_citrus_odor_of_a_seabird_crested_auklet_Aethia_cristatella_evolutionary_convergence_in_chemical_ecology}, author = {Hector D. Douglas_III and Jason E. Co and Tappey H. Jones and William E. Conner} }