RESIDUAL TOXICITY OF SELECTED INSECTICIDES TO HETEROPTERAN PREDACEOUSSPECIES (HETEROPTERA, LYGAEIDAE, NABIDAE, PENTATOMIDAE) ON SOYBEAN

Residual toxicity of selected insecticides to the heteropteran predato rs Geocoris punctipes (Say) adults, Nabis reseipennis Reuter adults, a nd Podisus maculiventris (Say) nymphs arid adults, was evaluated by ex posing predators to so! bean foliage (treated ill the field) in petri dishes. Toxicity of chlorfenapyr residues on soybean foliage was great er than that of the standard insecticide, permethrin, and another new compound, emamectin benzoate, to all 3 predaceous species. Methyl para thion-treated foliage was significantly more toxic to G. punctipes tha n were the remaining insecticides, except chlorfenapyr, 6 h after appl ication; however, by nf h after application, percentage mortality of G . punctipes declined fr om 100 to 11.7% following exposure to methyl p arathion residues. Duration of chlorfenapyr residues was evident up to 72 h after application, and chlorfenapyr-treated foliage was signific antly more toxic to G. punctipes than all other insecticides 24 to 72 h after application. Insect predators are highly mobile and spend cons iderable time searching for prey species on agronomic plants. Thus, in secticides with persistent foliar residues generally discriminate agai nst Predaceous species as they search for prey species or when they re colonize fields previously treated with insecticides.