Effect of insecticide treated soil on movement of third instar western corn rootworms (Coleoptera : Chrysomelidae)

The effect of insecticide treated soil on the distribution of third instar Diabrotica virgifera virgifera (LeConte) was investigated using a choice te st. Larvae were allowed the option of remaining on untreated soil or moving into soil containing a concentration of insecticide. In tests with organop hosphates (terbufos, chlorethoxyfos, and fonofos) fewer larvae were recover ed from treated soil compared to untreated soil. An inverse relationship wa s found between the percent of larvae which were recovered in treated soil and the concentration of insecticide in the soil. No significant relationsh ip could be found in tests in which tefluthrin, a pyrethroid, was used for soil treatment. Results indicate that D. virgifera virgifera larvae are abl e to detect and avoid the presence of organophosphates in the soil.