Effect of Early Season Insecticide Applications on Major Predaceous Arthropods in Cotton Fields Under An Integrated Control Program1

Five insecticides, some in different formulations, were tested for their effects on predator populations and plant bugs in cotton fields. The materials fell into 4 groups according to toxicity to predators: (1) high toxicity: fenthion emulsifiable concentrate (EC) and trichlorfon EC; (2) moderate toxicity: trichlorfon ultra low volume (ULV); (3) low toxicity: dimethoate, disulfoton, fenthion ULV, and propoxur; and (4) limited toxicity: trichlorfon 50% SP. The sensitivity of the predators to the insecticidal applications were in the following order: (1) high sensitivity: Orius insidiosus (Say) and Hippodamia convergens Guerin Meneville; (2) high 10 moderate sensitivity: Coleomegilla maculala (Dc Geer): (3) moderate sensitivity: Nabis roseipennis Reuter, N. alternatus Parsley, N. americoferus Carayon, Geocoris punctipes (Say), and Chrysopa spp.; (4) low sensitivity: Scymnus spp. and the spider complex. The spider complex was much less sensitive to insecticidal applications than were the other predators. The best plant bug control was obtained with dimethoate and fenthion EC. Dimethoate appeared to be much less toxic to the predator populations than fenthion EC.