Taste chemoreception is essential for animals to select suitable foods. Gustatory sensilla concentrated on mouthparts, other external appendages, or the food canal are responsible for transduction of chemical stimuli into nerve signals that trigger behavioral acceptance or rejection of a potential nutrient source. Insects have primary taste neurons containing both a dendrite and a direct axonal connection to the central nervous system, whereas receptor cells and afferent neurons are separated by a synapse in vertebrates. Taste receptor proteins have not been successfully purified or cloned from any animal to date. Our recent work with western corn rootworm beetles, Diabrotica virgifera virgifera LeConte, implicates a γ-aminobutyric acid (GABA)/glycine receptor in the perception of phago-stimulants and -deterrents. GABA stimulates feeding in herbivorous members of four orders of insects. The merits of this ligand-gated receptor model for chemoreception of 'sweet', 'bitter' and other taste classes will be contrasted with those proposed from vertebrate studies. Possibly one receptor gene family allows for insect perception of both food cues and potentially toxic non-host or environmental chemicals prior to their action at critical internal sites. Studies of taste receptors offer advantages over other insect neuroreceptors by their external location which simplifies ligand pharmacodynamics and allows coupled use of behavioral and electrophysiological methods to directly link receptor pharmacology with function.
All Science Journal Classification (ASJC) codes
- Insect Science