Role of gustatory sensilla in host recognition and feeding behavior of the Colorado potato beetle, Leptinotarsa decemlineata (Coleoptera, Chrysomelidae)

The role of gustatory sensilla in host recognition and feeding behavior of adult Colorado potato beetles, Leptinotarsa decemlineata (Say), on potato (host) and tomato (non-host) leaves was studied. The galeal gustatory sensilla were shown to play a major role in host selection and feeding. Ablation of these sensilla resulted in reduced discrimination between host and non-host. Beetles without these sensilla fed on normally rejected tomato.; Operated beetles also spent a longer time examining and consumed much less on potato. Effects of host and non-host leaf residues as well as solanine and tomatine on galeal sensory responses to leaf alcohols were examined using electrophysiological techniques. Tomato, but not potato, residue suppressed the galeal response suggesting chemicals in tomato residue are responsible for the suppression. Both alkaloids also suppressed the response indicating the complexity of chemical basis under which the response was suppressed. Numbers of chemosensilla on the inner surface of the adult beetle labrum were investigated using scanning electron microscopy. They were shown to be putative gustatory sensilla with a single pore at the tip.