Seasonal variation in numbers of the rabbit flea on the wild rabbit

Abstract

Samples of rabbits were obtained throughout each month over the 4-year period 1967–70. All fleas were removed, sexed and counted and the reproductive condition of the rabbits recorded. Rabbit fleas Spilopsyllus cuniculi (Dale) were present on both sexes of rabbit at all times of the year. In each year significantly high numbers of fleas were found on the rabbits in January, February, March and April and significantly low numbers in August, September and October. Mean flea counts were significantly higher on female rabbits than on males during April, May and June. During the rest of the year counts from each sex of host did not differ significantly. There were significant differences in flea numbers between years. More female than male fleas were found on both sexes of host throughout the year. The rabbit population sampled is shown to be typical of post-myxomatosis populations with regard to breeding performance and juvenile mortality. The relationship of the observed patterns of change in flea numbers to host and flea breeding and to host behaviour, population size and structure is discussed.

Myxomatosis: the emergence of male and female European rabbit fleasSpilopsyllus cuniculi(Dale) from laboratory cultures

“…His graphs indicate that the sex ratios for October and November were lower than those reported by Mead-Briggs et al (1975). The variations from 1 :1 in the sex ratios found during this study were not wide enough to make necessary any changes in the techniques of flea release in the field.…”

“…The fairly consistent higher sex ratio in the secondary emergence may help explain some of the data presented by Mead-Briggs, Vaughan & Rennison (1975) in their study of the seasonal variations of European rabbit flea numbers in the United Kingdom. They found a marked preponderance of female fleas on adult rabbits during August and September (0.67: 1 and 0.76: 1) but not during October and November (0.96:1 and 1.28:1).…”

Myxomatosis in farmland rabbit populations in England and Wales

“…Disease prevalence in spring peaked between February and April, soon after the start of the main rabbit breeding season in January or February, when fleas become more active in seeking pregnant females (40). Any observed differences in timing of spring peaks between years or sites could have been due to variations in the onset of pregnancies (in turn affected by prevailing food and weather conditions) and to the relative density of and proportions of recovered rabbits in the spring host population.…”

“…Early peaks followed the dispersal of fleas from reproductive females at the end of the main breeding season in June or July, whereas later peaks followed the progressive transference of fleas from dead rabbits to live survivors during heavy autumn mortality due to predation, etc. (40). This mortality occurred mainly between August and December, and is likely to have been a more gradual process than the sharper start and finish of the breeding season, making the later peaks of disease prevalence less well defined than earlier peaks.…”

“…Considerably fewer fleas were found on juvenile than on full-grown rabbits at Bridgets Farm, in agreement with the observations of Allan (39) and Soriguer (49). Thus juveniles should be relatively less at risk of infection, until they progressively acquire fleas as immatures (4-10 months old) during autumn (40); this is another factor responsible for the low numbers of infected juveniles recorded, and may also influence the seasonal prevalence of myxomatosis.…”