Contact chemical information guides mosquito behavioural decisions

Mosquitoes rely on chemical cues detected by sensory systems to guide behavioural decisions essential for survival and reproduction. While volatile olfactory cues are well studied, how non-volatile chemicals are detected and influence behaviour remains poorly understood. Here, we investigated the neuroethological effects of piperine, a plant-derived alkaloid from black pepper (Piper nigrum), and black pepper extract (BPE) in Aedes aegypti. Our results showed that piperine reduced blood feeding in a dose-dependent manner on artificial membrane feeders and significantly decreased biting on human skin. Similar effects were observed with BPE. Restricting contact with the feeder revealed that piperine deterred feeding only when females could contact it with their tarsi, supporting a role for tarsal contact chemoreception in the decision to feed. Piperine and BPE also deterred oviposition, indicating that the same chemical stimulus modulates distinct behavioural decisions in different stages of the life cycle. In larvae, exposure to piperine induced early motor disturbances and strongly reduced activity, followed by complete mortality within 24 h, while BPE produced stronger effects. Together, these results show that a plant-derived stimulus can influence distinct behavioural outputs across mosquito life stages, from sensory-guided decisions in adults to motor function in larvae, highlighting the importance of chemical information in shaping mosquito behaviour.