Population-dependent effects of Orco on olfactory-guided behavior and lifespan in Callosobruchus maculatus

BACKGROUND: The olfactory co-receptor (Orco) plays a central role in insect olfactory perception and chemical communication. However, whether the phenotypic effects associated with Orco differ across independently sourced populations remains unclear. RESULTS: We compared mating-related behavior, olfactory-guided responses, and lifespan between two independently sourced populations of Callosobruchus maculatus (Population A and Population B). Males from the two populations exhibited significant differences in mating latency and copulation duration. RNA interference (RNAi)-mediated knockdown of Orco significantly reduced mating-related behavioral responsiveness and antennal electrophysiological activity in both populations, confirming its essential role in olfactory function. Group-level behavioral analyses revealed a significant effect of Orco knockdown on odor-guided aggregation dynamics over time, while no significant effect of population was detected. In addition, Orco knockdown extended male lifespan in Population A but had no detectable effect in Population B. CONCLUSION: Orco is required for mating-related behavioral responsiveness in C. maculatus, and disruption of this conserved gene produces population-dependent phenotypic effects. These findings demonstrate that conserved olfactory components can generate variable behavioral and physiological outcomes across populations, highlighting the importance of considering population-level variation when interpreting gene function. © 2026 Society of Chemical Industry.