The Aversive Response of the Locust Locusta migratoria to 3-Octanone, an Odorant from Fungal Pathogens, Is Mediated by a Chemosensory Protein

This is the authors' abstract. We don't add key points for this paper.

(1) Locusts are important agricultural pests. Identifying harmful substances and avoiding them is important for locusts’ survival; their abilities to do so remain to be clarified. (2) We examined the electrophysiological (electroantennogram (EAG) and single sensillum recording (SSR)) and behavioral responses (preference behavior in a T-maze) of locusts to 18 different compounds; (3) Of these 18 compounds, 9 elicited strong EAG responses, and 3 elicited SSR responses of neurons expressing locust odorant receptor 3 (LmigOR3). The 11 chemicals that elicited stronger EAG or SSR responses were selected for evaluation of the behavioral responses of locusts. Only 2-heptanone induced significant attraction responses in locusts at the tested concentration. RNA interference (RNAi) of LmigOR3 and SSR experiments revealed that LmigOR3 could detect 2-heptanone and 3-octanone. However, in behavioral experiments, RNAi of LmigOR3 did not alter 2-heptanone-induced attraction but increased attraction by 3-octanone. (4) Our results suggest that the broadly tuned receptor expressed in a heterologous expression system exhibits a narrow electrophysiological response spectrum, and the aversive response of locusts to 3-octanone, an odorant from fungal pathogens, natural enemies, and non-host plants, is mediated by LmigOR3. These findings enhance our understanding of the complex olfactory recognition mechanism in insects.