Medium-chain fatty acids and aldehydes are ubiquitous volatiles that influence insect-plant interactions. However, the molecular mechanisms of their perception in most insect pests remain elusive. Here, we report that two ionotropic receptor paralogues, IR75q2.1 and IR75q2.2, diverged but complemented in perception of these volatiles in Plutella xylostella. A functional study with Xenopus oocyte-two-electrode voltage clamp recording (XOE-TEVC) demonstrated that two IR75q2s greatly diverged in response to C5-C10 compounds, with IR75q2.1 being responsive to C5-C6 and C8 compounds, while IR75q2.2 responds to C8-C10 counterparts. Behavioral assays showed that the best ligands of IR75q2.1 were attractive, but the best ligands of IR75q2.2 were repellent for the moths. Finally, CRISPR/Cas9-mediated knockout of the two IRs markedly reduced responses of adults to those compounds, establishing their important role in perception of medium-chain compounds. Our study provides the molecular targets for development of behavior-based control strategies against P. xylostella.
Wang et al. (Wed,) studied this question.