Toxicities of insecticides to neonate larvae of susceptible (Stoneville) and pyrethroid-resistant (ICI) strains of the tobacco budworm, Heliothis virescens (F.), were measured using a glass liquid scintillation vial technique. Results showed that ICI neonates were resistant to all pyrethroids tested. We observed no resistance to alternate insecticides including organophosphates, carbamates, avermectin, and rotenone. Several insecticide combinations were synergistic against resistant neonates. Chlordimeform synergized almost all insecticides tested; synergism was usually greater with susceptible than with resistant neonates. Piperonyl butoxide synergized cypermethrin in susceptible and resistant neonates. In combination with chlordimeform, piperonyl butoxide was more synergistic against resistant neonates. The resistance spectrum of the ICI strain suggests that target site resistance to pyrethroids is most important in neonate larvae and that metabolic resistance is of secondary importance. Tests with adult tobacco budworms suggested that both target site and metabolic resistance were present, with target site resistance being more important. The similarity of resistance in adults and neonates confirms the validity of adult monitoring in predicting resistance in neonates, the stage at which insecticide control is usually aimed.
Document Type: Research Article
Publication date: December 1, 1989
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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.