Reinfestation analysis to estimate ectoparasite population size, emergence, and mortality

The key components of ectoparasite vectorial capacity are poorly known, and no estimates of absolute population size for nest ectoparasites nor average longevity under natural conditions are available. A simple method to estimate these and other population parameters is suggested here, using body infestation data obtained by a specific host sampling design and the reproductive status of female ectoparasites. In contrast to mark-release-recapture techniques, this method requires minimal effort. Data on fleas, Synosternus cleopatrae (Rothschild), infesting gerbils, Gerbilus anderosoni allenbyi Thomas, were used as a preliminary test of this method. Thus, the average absolute density of female S. cleopatrae per host varied from seven in June to 24 in September; average female longevity varied from 17 to 5 d in that period. The quality of the parameter estimates was assessed by computer simulations to evaluate their variance and by comparison with the data available on fleas. The simulation indicated that estimates of absolute population size and proportion of the corporeal subpopulation were robust, but estimates of emergence rate, mortality rate, and average longevity were considerably less. The method's efficiency depends on the infestation rate and was considered suitable for medium to high counts of ectoparasites infesting solitary hosts.