Variability of gustatory responsiveness to phenylalanine in the generalist caterpillar, Grammia geneura (Lepidoptera, Arctiidae)

Electrophysiological recordings were made from maxillary taste sensilla of the caterpillar Grammia geneura, stimulated with the deterrent amino acid, phenylalanine. High levels of variability were noted and different potential causes examined. Little variation was detected with respect to standardized intra-individual tests, phenylalanine concentration, previous food type or time of day. Some changes were observed in relation to age, but could not account for the overall variation found. Major differences in responsiveness depended on cohort and the possibility of important genetic differences is discussed.