Can the nematode Capillaria hepatica regulate abundance in wild house mice? Results of enclosure experiments in southeastern Australia.

The hypothesis that a liver-inhabiting nematode, Capillaria hepatica, can regulate abundance of the house mouse (Mus domesticus) was tested in enclosures, in southeastern Australia. Changes in mouse abundance, and the relationship between mortality and host abundance were compared in three treatment and three control populations. Any effect of C. hepatica on mouse abundance was masked by an unknown regulating factor(s). This factor(s) caused density-dependent mortality in the control and treatment populations and, together with strong seasonal trends in parasite transmission, confounded our test of the ability of C. hepatica to regulate the abundance of house mice. The seasonal trends in transmission have important implications for the potential of this parasite as a biological control agent and for models of the interaction of C. hepatica and mouse populations. Transmission of C. hepatica apparently occurred throughout the 18 month study, further supporting its potential as a biological agent in the control of mouse plagues in this region.