Effects of Several Commonly Used Insecticides on Cornfield Carabids in Iowa1

Adult carabids Scarites substriatus (Haldeman), Harpalus Pensylvanicus (De Geer), Pterostichus chalcites (Say), Bembidion rapidum (LeConte), and, B. quadrimaculatum (L.) were field-collected and exposed to several commonly used cornfield insecticides. The beetles were directly exposed to recommended field rates of carbofuran, phorate, terbufos, aldrin, carbaryl, leptophos, trichorfon, methomyl, and toxaphene. Beetles were also fed dead larva of the black cutworm, Agrotis ipsilon (Hufnagel), poisoned by carbofuran, carbaryl, trichlorfon, methomyl, and toxaphene. There were significant differences in mortality among beetles species and chemical treatments. Phorate and terbufos granules, carbofuran, methomyl, and carbaryl sprays produced high mortalities, and carbofuran granules, carbaryl, and leptophos baits caused low beetle mortalities.