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Topical toxicities of three pyrethroids (permethrin, cypermethrin, and fenvalerate), one carbamate (carbaryl), and one organophosphate (methyl parathion) were determined with third instars of two Helicoverpa zea (Boddie) strains that were established from field collections in com and cotton where control difficulties with pyrethroids were experienced. The data were compared with those of an insecticide-susceptible laboratory strain. Resistance ratios (RR at LD50 and LD90) indicated that Illinois-strain larvae were resistant to permethrin (5.2- and 10.8-fold), cypermethrin (3.0- and 18.0-fold), and carbaryl (2.6- and 2.7-fold), whereas Arkansas-strain larvae were resistant to permethrin (5.7- and 8.8-fold), cypermethrin (5.0- and l0.0-fold), fenvalerate (2.2- and 2.7-fold), methyl parathion (3.2- and 3.2-fold), and carbaryl (3.1- and 1.9-fold). Results of studies of the effect of synergists on toxicity of cypermethrin to larvae of the Arkansas strain were inconclusive; however, they suggested that both metabolic and nonmetabolic (target site) resistance mechanisms could be involved.
Document Type: Research Article
Publication date: December 1, 1993
More about this publication?
Journal of Economic Entomology is published bimonthly in February, April, June, August, October, and December. The journal publishes articles on the economic significance of insects and is divided into the following sections: apiculture & social insects; arthropods in relation to plant disease; forum; insecticide resistance and resistance management; ecotoxicology; biological and microbial control; ecology and behavior; sampling and biostatistics; household and structural insects; medical entomology; molecular entomology; veterinary entomology; forest entomology; horticultural entomology; field and forage crops, and small grains; stored-product; commodity treatment and quarantine entomology; and plant resistance. In addition to research papers, Journal of Economic Entomology publishes Letters to the Editor, interpretive articles in a Forum section, Short Communications, Rapid Communications, and Book Reviews.