Temperature-Toxicity Relationships of Pyrethroids on Three Lepidopterans

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Abstract
Larvae of the cabbage looper, Trichoplusia ni (Hübner), fall armyworm, Spodoptera Frugiperda (J. E. Smith), and tobacco budworm, Heliothis virescens (F.), were each topically bioassayed for permethrin, fenvalerate, and deltamethrin (S)-α-cyano-3-phenoxybenzyl cis -(1R)-3-(2,2-dibromovinyl)-2,2-dimethylcyclopropanecarboxylate) toxicity at each of three temperatures (15.6, 26.7, and 37.8). Pyrethroid toxicity to T. ni and H. virescens was deltamethrin > fenvalerate > permethrin, whereas that of S. frugiperda was deltamethrin > permethrin > fenvalerate. All three compounds displayed a negative temperature coefficient for T. ni , as did permethrin for S. frugiperda , and permethrin and cypermethrin for H. virescens . Both fenvalerate and deltamethrin exhibited either neutral or positive temperature coefficients for S. frugiperda and H. virescens .