Assessment of damage to annual pastures by the pasture cockchafer, Aphodius tasmaniae Hope, in South Australia

Abstract

The larvae of A. tasmaniae cause damage to extensive areas of pasture in the higher rainfall areas of South Australia. At present there is no reliable information about the densities of larvae which can be treated economically.

Experiments on damage assessment were conducted in naturally infested pasture. In the first experiment pastures were ungrazed by livestock. Available pasture dry matter from four pastures, sprayed with lindane to control larvae, was compared with dry matter from adjacent, untreated pasture. There were no differences in available pasture which could be attributed to A. tasmaniae at any of the sites. The results indicated that the apparent damage caused by A. tasmaniae was a combined effect of grazing livestock and larval feeding. Therefore, a second experiment was conducted in which the pastures were grazed evenly with livestock. In this experiment a significant difference in available pasture dry matter between treatments was found, and this could be attributed mainly to A. tasmaniae. The results suggested that this technique was suitable and could be extended to assess the damage to pasture caused by a wide range of densities of A. tasmaniae larvae.