A BEHAVIORAL AND ELECTROPHYSIOLOGICAL STUDY OF THE ROLE OF TARSAL CHEMORECEPTORS IN FEEDING BY ADULTS OF SPODOPTERA, HELIOTHIS-VIRESCENS AND HELICOVERPA-ARMIGERA

Adult females of Spodoptera littoralis, Spodoptera frugiperda, Helicoverpa armigera and Heliothis virescens were tested with a range of sugars, amino acids, allelochemics and plant extracts. In behavioural assays, freely moving insects made tarsal contact with glass-fibre discs treated with test solutions and the occurrence of proboscis extension was noted. Electrophysiological recordings from tarsal chemoreceptors identified different neurones responsive to sugars, amino acids and allelochemicals. Three neurones responded to the plant extracts. An ANOVA showed that the electrophysiological responses of individuals within a species to a particular solution varied more than the responses from different tarsal sensilla on an individual. Data from the behavioural and electrophysiological bioassays from all four species are compared to identify differences in sensory coding between the species. The results are combined with those of an earlier study to compare the roles of tarsal and proboscis sensilla in the assessment of food material. © 1990.