Breeding of the rabbit flea (Spilopsyllus cuniculi (Dale)), controlled by the reproductive hormones of the host

THE rabbit flea (S. cuniculi) is a host-specific parasite of the rabbit. Before the outbreak of myxomatosis in Britain all populations of rabbits examined from the mainland were infested and the flea index was high1,2. The first hint that the breeding cycle of the flea was linked to the hormone cycle of the host came from Allan's1 observation that shortly before the breeding season commenced, female rabbits carried an extra load of fleas. Further observation enhanced this view, and Rothschild2,3 suggested that the breeding cycle, especially copulation, was under the influence of the sex hormones of the host. This suggestion was followed up by Mead-Briggs4, who proved that: (a) maturation of the ovaries of female rabbit fleas could only take place on a pregnant female rabbit; (b) that immediately after parturition the fleas from the does were to be found in the nest containing the young rabbits, where they fed on the young and laid eggs.