Speaker
Description
Odorant receptors (ORs) are key components of the insect olfactory system and are primarily expressed in antennae, where they mediate the detection of environmental volatiles. Interestingly, certain ORs have also been identified in non-antennal tissues like the ovipositor, suggesting possible roles in regulating oviposition behavior. In this study, we performed transcriptomic analyses across different tissues of the noctuid moth Spodoptera littoralis and identified four ORs expressed in the ovipositor. Using structure-based virtual screening (SBVR) combined with experimental validation, we could identify ligands for three out of the four ORs. Oviposition behavioral assays revealed that four out of the six optimal ligands exhibited significant oviposition deterrence in female moths. To determine whether the ovipositor plays a role in detecting these cues, antennal ablation was conducted prior to oviposition assays. The deterrent effects were largely abolished, except for indole, suggesting that ovipositor may contribute to its detection. We subsequently utilized a four-arm olfactometer to investigate whether these ligands elicit orientation responses in moths. The results showed that all tested compounds elicited significant repellent responses. Notably, indole continued to induce avoidance behavior after antennal ablation, supporting a potential role of the ovipositor in its detection. Collectively, these results provide new insights into the molecular and behavioral mechanisms of oviposition site selection and expand our understanding of peripheral olfactory mechanisms in moths.
