The ecology of Oncopera fasciculata (Walker) (Lepidoptera: Hepialidae) in South Australia. 5. Changes in the environment of O. fasciculata associated with the development of country grey for Agriculture.

Abstract

Before County Grey was developed for agriculture, Oncopera fasciculata (Walker) probably was restricted by excessive wetness to the higher, drier portions of the poorly drained soils, and by dryness to the lower, moister portions of the well-drained soils. Even in these places the insect probably was not able to maintain large numbers because suitable food was scarce. Steps in the development of the area for agriculture have included artificial drainage, clearing of woodland and scrub, the use of phosphatic and trace-element fertilizers, and the establishment of pastures consisting of subterranean clover (Trifolium subterraneum L.) and other introduced clovers and grasses. This development has provided a more favourable environment for O. fasciculata. Artificial drainage reduced the chances of exposure to excessive wetness, and the establishment of pastures composed of clovers and perennial grasses not only provided protection for the eggs and young larvae against evaporation, but also made available a greater amount of good-quality food for the larvae.