Human Odour Attracts Anopheles and Culex Mosquitoes only Upon Sweating

Mosquitoes transmit many pathogens, like malaria (by Anopheles ), lymphatic filariasis (by Culex ), Zika virus and Dengue virus (by Aedes ). Female mosquitoes have robust preferences for human odours over animal odours. A recent study showed that some olfactory glomerulus within the Aedes aegypti was significantly activated by human odours but weakly activated by animal odours. Among the odour chemicals, decanal and undecanal played dominant roles. However, most previous studies adopted lab-reared mosquitoes who were investigated in 1-way or 2-way enclosed tunnels. Here we studied wild Anopheles and Culex mosquitoes in an open environment and found that no mosquito could be caught without either CO 2 or heat, indicating that both CO 2 and heat gate the responses to other odorant stimuli. Only wet clothes soaked with human sweat (but not human-scented dry clothes) attracted 20–50% more mosquitoes at 37°C and showed no effect at 25°C. Thus for Anopheles and Culex , human odour may only play a significant role in the host-seeking behavior only upon sweating. And neither decanal nor undecanal attracted mosquitoes in our field study, indicating inefficacy of any single volatile substance.