Role of galeal sensilla in host recognition and feeding behaviour of the Colorado potato beetle

Abstract. Close-range interactions with plants and the early stages of feeding behaviour of adult Colorado potato beetles, Leptinotarsa decemlineata (Say) (Coleoptera: Chrysomelidae), were studied using beetles with and without various mouthpart sensilla. Representative host, potato (Solarium tuberosum) , and non-host, tomato (Lycopersicon esculentum) , leaves were treated very differently by beetles with and without their galeal or palpal sensilla. Galeal sensilla were particularly important for beetles interacting with these two plants. Compared with normal beetles, fewer beetles without galeae fed on potato leaves, and those that did feed spent more time assessing the plant and took more bites before feeding. On tomtato, more beetles without galeae fed, spent less time assessing the plant and took fewer bites before feeding. Beetles without galeae also had lower consumption rates on potato and higher consumption rates on tomato. Beetles were very reluctant to feed on tomato if the galeae were present so removal of maxillary sensilla was studied only on potato. Without the sensilla on the maxillary palpi only the time between first touch and first bite was affected (lengthened). The importance of galeal sensilla in host recognition by this species and the implications for chemosensory studies are discussed here and in a companion paper.