CONTACT AND VOLATILE TOXICITY OF INSECTICIDES TO BLACK CUTWORM LARVAE (LEPIDOPTERA, NOCTUIDAE) AND CARABID BEETLES (COLEOPTERA, CARABIDAE) IN SOIL

Field plot studies were conducted for 3 yr in conventional and no-tillage conditions to assess the contact and volatile toxicity of four granular soil insecticides-chlorpyrifos, DPX-43898 (O,O-diethyl-O-1,2,2,2-tetrachloroethyl phosphorothioate), fonofos, and terbufos-against fourth-instar black cutworm, Agrotis ipsilon (Hufnagel), and adult carabids. Abnormally high precipitation and low soil temperature hindered acquisition of a lethal dose by A. ipsilon from insecticide granules. Image analysis indicated that percentage contact area may contribute to differences in acquisition of soil insecticides by A. ipsilon larvae and two prevalent, predatory carabid species, Abascidus permundus L. and Pterostichus chalcites Say. Organophosphate insecticides active at the kilogram per hectare level in soil and possessing high vapor pressures (> 10 mPa) were poor candidates for control of A. ipsilon and contributed to a reduction in endemic carabid populations.