Monitoring for Pyrethroid Resistance in Relation to Body Weight in Adult Helicoverpa armigera (Hubner) (Lepidoptera: Noctuidae)

Publisher Website
Google Scholar
Abstract
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 μg/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.