Laboratory tests on the stability of insecticide resistance in mosquito larvae indicate that some colonies experience a reduction from their initial level of resistance to both chlorinated hydrocarbons and organophosphorus compounds when selection pressure is not maintained. The rapid decline in resistance to organophosphorus insecticides parallels observations made on laboratory colonies of the adult house fly, Musca domestica L. Laboratory tests conducted on a malathion-resistant strain of Culex tarsalis Coq. and a parathion-resistant strain of Aedes nigromaculis (Ludlow) indicated that resistance levels in field populations of both strains has declined from the previous year. Field tests in 1958 Oil the parathion-resistant strain of A. nigromaculis indicated that formulation difficulties were not responsible for the number of surviving larvae observed after application of o.1 llb./aere of parathion. These findings substantiate earlier laboratory tests reported elsewhere that physiological resistance to parathion existed in this strain. Field tests conducted in 1959 indicated a lower level of resistance to malathion and parathion than for 1958. Fewer treatments and, in the case of parathion-resistance, the substitution of a different insecticide may have been responsible for the decline in resistance. Rotation of organophosphorous insecticides where cross tolerances do not exist, as well as compounds with differing modes of action, are suggested as a possible means of averting the development of resistance. Prolonged and frequent use of anyone type of insecticide on house flies or mosquitoes should be discouraged.
Document Type: Research Article
Publication date: December 1, 1960
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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.