The relationship between pupal weight and phenotype for pyrethroid resistance in adults was determined in laboratory and field collections of Helicoverpa armigera (Hubner). Phenotype was determined by placing adults for 48 h into a scintillation vial, the inside of which had been coated with a diagnostic dose of the pyrethroid fenvalerate. For laboratory strains, a dose of 90 ~g/vial of fenvalerate killed >94% of susceptible individuals and <10% of resistant individuals. In 1987 and 1988, the body weight and resistance frequencies of overwintering pupae differed among samples from several host plants. In 1987, pupae from maize (Zea mays L.) and cotton (Gossypium hirsutum L.) crops were heavier than those from pigeon pea (Cajanus cajan (L.) Millsp.) crops; in 1988, pupae from cotton crops were lighter than those from maize or sunflower (Helianthus annuus L.) crops. On average, suscepfible pupae were lighter than resistant pupae. However, differences in resistance frequencies among samples were not caused by differences in body weight. The adult vial test is a simple and reliable method of determining the pyrethroid resistance phenotype of field-collected pupae and larvae and in laboratory-reared insects.
Document Type: Research Article
Publication date: June 1, 1990
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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.