The Scent of Deception: Does the Hornet Clearwing Sesia apiformis Chemically Mimic Vespa crabro?

Avoiding attack requires harmless species to escape, prevent recognition as prey, or remain undetected. Clearwing moths display hymenopteran mimicry that may involve multiple sensory modalities-from visual and locomotor to acoustic cues. Here, we tested whether the morphological and acoustical resemblance of the hornet clearwing Sesia apiformis to the hornet Vespa crabro also extends to chemical traits by comparing their cuticular hydrocarbon (CHC) profiles. Compositional and quantitative analyses revealed no evidence of chemical mimicry between S. apiformis and V. crabro; instead, the moth exhibited an approximately sixfold reduction in total CHC abundance in comparison to the hornet and a complete absence of alkenes, compounds known to function as key recognition cues in insect predator-prey interactions. These results suggest that S. apiformis does not converge on the chemical profile of its model and are consistent with the possibility that its reduced CHC profile contributes to lowered detectability by predators. However, the ecological significance of our findings remains to be tested through behavioural assays with potential predators. We discuss the likely predator guild of S. apiformis and the selective pressures these predators may exert on chemical detectability. Comparative analyses across closely related lepidopteran families (Cossidae, Zygaenidae, Heterogynidae, and Castniidae) revealed CHC profiles that differed markedly in both composition and abundance from that of S. apiformis. Together, these findings indicate that the reduced and simplified CHC profile in S. apiformis is unusual among related taxa and may represent a mechanism contributing to reduced predator recognition, highlighting the potential importance of signal suppression, alongside signal elaboration in predator-prey communication.