Population Dynamics of Mus Musculus and Its Parasites in Mallee Wheatlands in Victoria During and After a Drought.

Abstract

The population dynamics and cestodes, nematodes, ticks and fleas of wild mice in mallee wheatlands in Victoria, Australia, were monitored every 6th week from November 1982 to November 1983. Presence of Acarina and Nosopsyllus spp. in a total of 355 mice from farm buildings, crops and near permanent water was independent of that of Hymenolepis fraterna, Taenia taeniaeformis, Aspiculuris tetraptera, Syphacia obvelata and Muspicea borreli. S. obvelata was recorded in every habitat throughout all seasons (although its prevalence was significantly higher in winter near permanent water) and was the most prevalent helminth (67.0%). Overall prevalences of H. fraterna, T. taeniaeformis, A. tetraptera and M. borreli were 7.0, 5.3, 6.2 and 1.7% resp. The overall prevalence of the ticks Radfordia affinis and Myobia murismusculi was 93.9% and that of Nosopsyllus spp. was 36.7%. Other ticks were found on 39.8% of mice. The number of parasite species and prevalence of infection were lowest during severe drought in summer. After the drought parasite prevalence increased significantly . Prevalence of some species differed with habitat, both within and between seasons, but the reasons for the differences were unclear. Prevalence and intensity of parasitism was independent of mouse population density. Muspicea borreli is recorded from Australia for the first time. ADDITIONAL ABSTRACT: The population dynamics and parasite fauna of wild Mus musculus were monitored every 6th week from November 1982 to November 1983 in the mallee wheatlands of northwest Victoria. Endo- and ectoparasites were examined in 355 mice sampled from farm buildings, crops and around permanent water. The presence of ectoparasites (myobiid mites and fleas of the genus Nosopsyllus) was independent of that of endoparasites (nasal mites, cestodes and nematodes). The number of parasite species and prevalence of infection were lowest in summer, a period of severe drought. After the drought, seasonal differences in the number of parasite species were not significant but the prevalence of parasite infection increased significantly. The prevalence and mean intensity of infection varied for each parasite species. The prevalence of many species differed with habitat, both within and between seasons. Generally, reasons for these differences were not clear. The prevalence and intensity of parasitism was independent of mouse population density.