Dispersion of grain beetles (Coleoptera) in grain partially treated with insecticide

Behavioral responses of Tribolium castaneum (Herbst) and Sitophilus oryzae L. to fenitrothion and of Rhyzopertha dominica L. to carbaryl and to bioresmethrin were tested by adding eggs (S. oryzae or R. dominica ) or pupae (T. castaneum ) to wheat unsprayed or sprayed with insecticide. Grain containing insects was placed above or below another layer of sprayed or unsprayed wheat so that insects could more freely between layers. The recommended application rate commonly used in Australia and a sublethal dosage of insecticide were tested. Numbers of live and dead adults and emigrants were counted. Results have implications for insecticide bioassay, population modeling, and in studies of the development of resistance.