Based on 48 h LD50 estimates from topical bioassays, cypermethrin was more toxic than permethrin to Helicoverpa zea (Boddie) larvae and adults; however, the two pyrethroids did not differ significantly in their relative toxicities to Spodoptera frugiperda (J. E. Smith) and Agrotis ipsilon (Hufnagle). Larvae of each species generally were more susceptible to cypermethrin and permethrin than respective adults. The only exception to this generalization occurred with H. zea where slight overlap of the 95% confidence intervals with larvae and adult males was observed with cypermethrin. Respective males and females of the three species usually did not differ significantly in their susceptibility to either cypermethrin or to permethrin; however, with A. ipsilon, females were more susceptible to permethrin than to cypermethrin. Several instances of greater than additive toxicity were noted when insects were treated with piperonyl butoxide, S,S,S-tri-n-butyl phosphorotrithioate (DEF), or amitraz 30 min before cypermethrin. DEF exhibited the broadest spectrum of synergistic activity.
How to translate text using browser tools
1 August 2001
Toxicity of Pyrethroids and Effect of Synergists to Larval and Adult Helicoverpa zea, Spodoptera frugiperda, and Agrotis ipsilon(Lepidoptera: Noctuidae)
K. Amin Usmani,
Charles O. Knowles
ACCESS THE FULL ARTICLE
It is not available for individual sale.
This article is only available to subscribers.
It is not available for individual sale.
It is not available for individual sale.
Journal of Economic Entomology
Vol. 94 • No. 4
August 2001
Vol. 94 • No. 4
August 2001
cypermethrin
Noctuidae
permethrin
synergism
toxicity