Factors Limiting the Distribution of the European Rabbit Flea, Spilopsyllus Cuniculi (Dale) (Siphonaptera), in Inland South Australia.

Abstract

The distribution of rabbit fleas in the Flinders Ranges in inland South Australia is generally confined to areas where annual average rainfall exceeds 200 mm. The fleas have not been able to become permanently established in more arid areas. They breed only when their host breeds and drought can inhibit breeding in the rabbit by drying up the green vegetation which is needed for its reproduction. Thus, if droughts are prolonged, rabbit fleas may not breed within their life-span and the population may become extinct. Other extremes of weather may also influence flea populations. In particular, low humidity during hot summers may cause heavy mortality. It appears that rabbit fleas will be limited to only a part of the range of distribution of their host and that in much of inland Australia they will not be useful vectors of myxomatosis. Other arthropods in South Australia also have distributions which show close association with climatic gradients, and the behaviour of rabbit flea populations at their extremes of distribution provides useful comparative data which aid our understanding of the distribution of other species.