Electrophysiological Characterization of Responses from Gustatory Receptor Neurons of sensilla chaetica in the Moth Heliothis virescens

Abstract

Discrimination of edible and noxious food is crucial for survival in all organisms. We have studied the physiology of the gustatory receptor neurons (GRNs) in contact chemosensilla (insect gustatory organs) located on the antennae of the moth Heliothis virescens, emphasizing putative phagostimulants and deterrents. Sucrose and the 2 bitter substances quinine and sinigrin elicited responses in a larger proportion of GRNs than inositol, KCl, NaCl, and ethanol, and the firing thresholds were lowest for sucrose and quinine. Variations in GRN composition in individual sensilla occurred without any specific patterns to indicate specific sensillum types. Separate neurons showed excitatory responses to sucrose and the 2 bitter substances quinine and sinigrin, implying that the moth might be able to discriminate bitter substances in addition to separating phagostimulants and deterrents. Besides being detected by separate receptors on the moth antennae, the bitter tastants were shown to have an inhibitory effect on phagostimulatory GRNs. Sucrose was highly appetitive in behavioral studies of proboscis extension, whereas quinine had a nonappetitive effect in the moths.

Cloning and expression pattern of a putative octopamine/tyramine receptor in antennae of the noctuid moth Mamestra brassicae

“…Interestingly, we have not observed any staining at the base of the sensilla chaetica (Fig. 4f), which are known, in other noctuids, to be involved in mechano/ contact chemoreception (Jorgensen et al 2007), suggesting that MbraOAR/TAR expression is restricted to olfactory sensilla in antennae. However, a modulatory effect on taste cannot be excluded, since MbraOAR/TAR signals have been detected in the proboscis, the main appendage carrying taste receptor neurones.…”

Dine or dash? Turbulence inhibits blue crab navigation in attractive–aversive odor plumes by altering signal structure encoded by the olfactory pathway

“…1976; Formaker and Frank, 1996;Jørgensen et al, 2007) suppress or inhibit the neural activity of receptor neurons that are excited by foodactivated cells.…”

Ligand carrier protein genes expressed in larval chemosensory organs of Bombyx mori

“…In the lepidopteran moths, Heliothis virescens possesses gustatory sensilla in the antenna (Jørgensen et al, 2007), and female Agrius convolvuli moths use tarsi to confirm host plants before oviposition (Shimoda and Kiuchi, 1988). To understand the roles of bmToL2 and bmObpL6 in the adult appendages, further studies should be carried out confirm whether B. mori has gustatory functions in the adult appendages.…”