Female-Biased Odorant Receptor LstiOR3 Mediates Oviposition Preference via Linalool Recognition in Loxostege sticticalis (Lepidoptera: Pyralidae)

The beet webworm, Loxostege sticticalis, whose oviposition behavior significantly affects population quantity and causes crop losses, has poorly understood olfactory mechanisms governing this behavior. Odorant receptors (ORs) play a critical role in the insect olfactory system. Here, three ORs (LstiOR1, LstiOR2, and LstiOR3) were cloned, with all highly expressed in female antennae. The two-electrode voltage clamp recording revealed that only LstiOR3 displayed broad tuning to nine host plant volatiles, especially linalool. Electroantennogram recordings confirmed that the nine ligands induced electrophysiological responses, with particularly strong responses observed for linalool in female antennae. Subsequently, dual-fragment RNA interference (RNAi) effectively silenced LstiOR3, significantly reducing the electrophysiological and behavioral responses of L. sticticalis to linalool. Additionally, molecular docking showed that LstiOR3 binds strongly to linalool through hydrogen bonds at VAL-199 and GLY-203. In summary, our studies elucidate the specific biological function of LstiOR3 via linalool detection in oviposition site selection.