Residual toxicity of selected insecticides to heteropteran predaceous species (Heteroptera: Lygaeidae, Nabidae, Pentatomidae) on soybean

Residual toxicity of selected insecticides to the heteropteran predators Geocoris punctipes (Say) adults, Nabis reseipennis Reuter adults, and Podisus maculiventris (Say) nymphs and adults, was evaluated by exposing predators to so! bean foliage (treated ill the field) in petri dishes. Toxicity of chlorfenapyr residues on soybean foliage was greater than that of the standard insecticide, permethrin, and another new compound, emamectin benzoate, to all 3 predaceous species. Methyl parathion-treated foliage was significantly more toxic to G. punctipes than were the remaining insecticides, except chlorfenapyr, 6 h after application; however, by nf h after application, percentage mortality of G. punctipes declined fr om 100 to 11.7% following exposure to methyl parathion residues. Duration of chlorfenapyr residues was evident up to 72 h after application, and chlorfenapyr-treated foliage was significantly more toxic to G. punctipes than all other insecticides 24 to 72 h after application. Insect predators are highly mobile and spend considerable time searching for prey species on agronomic plants. Thus, insecticides with persistent foliar residues generally discriminate against Predaceous species as they search for prey species or when they recolonize fields previously treated with insecticides.