SUSCEPTIBILITY OF PREDACEOUS HEMIPTERAN SPECIES TO SELECTED INSECTICIDES ON SOYBEAN IN LOUISIANA

Toxicity of selected insecticides to hemipteran predators [i.e., Geoco ris punctipes (Say), Nabis capsiformis Germar, Nabis roseipennis Reute r, and Podisus maculiventris (Say)] was evaluated by contact with foli ar residues and indirectly through the consumption of prey [i.e. soybe an looper, Pseudoplusia includens (Walker) ] previously exposed to ins ecticides. Methyl parathion and permethrin generally were more toxic t han newer insecticides after predators were exposed to treated foliage . Chlorfenapyr caused contact toxicity equal to permethrin and methyl parathion. Exposure to foliage treated with emamectin benzoate resulte d in lower mortality as compared with chlorfenapyr. Foliage treated wi th Bacillus thuringiensis Berliner subsp, kurstaki had the lowest cont act toxicity to hemipteran predators of all insecticides tested. Stand ard insecticides (i.e., methyl parathion and thiodicarb) caused low in direct toxicity to hemipteran predators after consumption of treated p rey. Chlorfenapyr caused significantly greater indirect toxicity than emamectin benzoate, permethrin, and thiodicarb to adult N. roseipennis . Consumption of chlorfenapyr-treated prey also caused significantly g reater mortality than imidacloprid, permethrin, spinosad, and thiodica rb to G. punctipes adults. These results demonstrate that most of the newer compounds were more selective than older insecticides. This grea ter selectivity will enable soybean producers to combat pests but cons erve resident beneficial arthropod populations that help restrain pest resurgence and prevent secondary pest outbreaks.