SELECTIVE SOIL ORGANIC-MATTER CONSUMPTION BY LARVAE OF ADORYPHORUS-COULONI (BURMEISTER) (COLEOPTERA, SCARABAEIDAE)

Analysis of the gut contents of third-instar larvae of the redheaded p asture cockchafer Adoryphorus couloni indicates that they feed prefere ntially on organic matter in soil under perennial ryegrass pastures, r ather than simply consuming the bulk soil indiscriminantly. Larvae seq uester carbonaceous material at 2-4 times its concentration in the ext ernal soil environment. This was confirmed by confining larvae in arti ficial soils with various proportions of organic matter, with the degr ee of assimilation depending on the size of the food particles. Better management of the organic matter in the root zone of pastures may hol d a key to the management of this pest.