Commercial permethrin elicits chemoreceptive responses on different <scp> <i>Anopheles gambiae</i> </scp> sensory appendages

BACKGROUND: For malaria mosquitoes, the ability to detect pyrethroid insecticides before coming into contact with an impregnated surface can be highly advantageous in terms of fitness. Such detection may lead to the development of behavioral modifications that help them to avoid commonly used vector control tools. A previous study has shown that malaria mosquitoes can detect different pyrethroid molecules without coming into contact with them, regardless of their physiological resistance status. However, the mechanisms underlying this detection are not yet fully understood. This study aimed to identify which chemosensory appendages in Anopheles gambiae are involved in the non-contact detection of permethrin, a widely used pyrethroid in malaria control. RESULTS: Behavioral responses to commercial permethrin headspace were recorded in female An. gambiae, in which specific sensory appendages were either removed or coated with resin to impair their chemosensory function. Additionally, electrophysiological recordings were performed on different sensory appendages: antennae, palpi and tarsi, to characterize their electrophysiological activity after permethrin stimulation. The behavioral assays revealed that tarsi were primarily responsible for mediating mosquito takeoff responses after permethrin headspace delivery. This finding was supported by significant electrophysiological tarsal responses to the insecticide. In contrast, removal of the antennae did not alter behavioral responses, although electroantennogram recordings indicated neural activity in response to the permethrin headspace. The palps showed neither behavioral nor electrophysiological responses. CONCLUSION: These findings indicate that An. gambiae detects commercial permethrin in vapor form using two distinct sensory appendages: the tarsi and the antennae, but with varying behavioral output. The results suggest that the non-contact detection of the insecticide may be mediated by chemosensory signaling pathways. Nonetheless, further research is required to identify the specific sensory mechanisms involved in the detection of pyrethroids in malaria mosquitoes, and their contribution to the evolution of behavioral adaptations against pyrethroid-based vector control tools. © 2026 The Author(s). Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.