Differential Susceptibility of German Cockroach (Dictyoptera: Blatlellidae) Sexes and Nymphal Age Classes to Insecticides
Authors: KOEHLER, PHILIP G.; STRONG, CHARLES A.; PATTERSON, RICHARD S.; VALLES, STEVEN M.
Source: Journal of Economic Entomology, Volume 86, Number 3, June 1993 , pp. 785-729
Publisher: Entomological Society of America
Abstract:Sexes and nymphal age classes of insecticide-susceptible and resistant strains of the German cockroach, Blattella germanica (L.), were evaluated for susceptibility to bendiocarb, chlorpyrifos, and cypermethrin. In all cases, late-stage nymphs had higher LC50s (µg per insect) and LD50s (µg/mg) than adult males. In most cases, these nymphs were also more difficult to kill than adult females. This reduced susceptibility to insecticides in late-instar nymphs occurred irrespective of weight differences, type of insecticide, or strain of cockroach. Females had significantly higher LC50s (µg per insect) than males for bendiocarb (resistant strain), chlorpyrifos (susceptible and resistant strains), and cypermethrin (susceptible strain). However, LD50s (µg/mg) for males and females were the same for bendiocarb (susceptible and resistant strains), chlorpyrifos (susceptible strain), and cypermethrin (susceptible and resistant strains). Resistance ratios for bendiocarb, chlorpyrifos, and cypermethrin were higher for some life stages and sexes than for others. Resistance ratios were 6-10 for bendiocarb in adult males and females, but ratios for 4- to 6-wk-old nymphs were 5-100. For chlorpyrifos, the resistance ratio was 7 for males but 20 for females. Males were 32-fold resistant to cypermethrin but 3- to 6-wk-old nymphs were 44-94-fold resistant.
Document Type: Research Article
Publication date: June 1, 1993
- 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.
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