Joint Action of Two Pyrethroids with Methyl-Parathion, Methomyl, and Chlorpyrifos on Heliothis zea and H. virescens in the Laboratory and in Cotton and Sweetcorn12

Abstract

Joint toxicity of 2 photostable pyrethroids with selected organophosphate and carbamate insecticides was evaluated on the corn earworm, Heliothis zea (Boddie), and the tobacco budworm, H. virescens (F.). The 2 pyrethroids were permethrin (5-benzyl-3-furyl methyl 2, 2-dimethyl-3-(2-methylpropenyl) cyclopropane-carboxylate) and Pydrin® (benzeneacetic acid, 4-chloro-alpha-(1-methylethyl)-cyana (3-phenoxyphenyl) methyl ester). Synergism of certain mixtures was indicated in topical experiments, especially with methyl-parathion: permethrin (10:1) on H. virescens. Potentiation of methyl-parathion: permethrin (9:1) also was suggested on H. zea, but not with methyl-parathion: Pydrin (9:1). However, efficacy of methomyl on H. zea was potentiated by both permethrin and Pydrin. Two years of tests in cotton, Gossypium hirsutum L., and sweetcorn, Zea mays L., verified the improved toxicity of pyrethroid mixtures with methyl-parathion. methomyl, and chlorpyrifos. In certain cases, these mixtures were effective at rates reduced to 0.1× the normal dosages.