Meeting Abstract
Mosquitoes are important vectors of disease and require sources of carbohydrates for reproduction and survival. Unlike host-related behaviors of mosquitoes, comparatively less is understood about the mechanisms involved in nectar-feeding decisions, or how this sensory information is processed in the mosquito brain. Here we show that Aedes spp. mosquitoes, including Aedes aegypti, are effective pollinators of the Platanthera obtusata orchid, and demonstrate this mutualism is mediated by the orchid’s scent and the balance of excitation and inhibition in the mosquito’s antennal lobe (AL). Furthermore, we show that the combination of odor and visual cues increase the ability of mosquitoes to locate the flowers. The P. obtusata orchid emits an attractive, nonanal-rich scent, whereas related Platanthera species – not visited by mosquitoes – emit scents dominated by lilac aldehyde. Calcium imaging experiments in the mosquito AL revealed that nonanal and lilac aldehyde each respectively activate the LC2 and AM2 glomerulus, and remarkably, the AM2 glomerulus is also sensitive to DEET, a mosquito repellent. Lateral inhibition between these two glomeruli corresponds to the level of attraction to the orchid scents: whereas the enriched nonanal scent of P. obtusata activates the LC2 and suppresses AM2, the high level of lilac aldehyde in the other orchid scents inverts this pattern of glomerular activity, and behavioral attraction is lost. Moreover, olfactory stimulation with the attractive orchid scent gates the attraction to visual objects, especially those with features similar to the orchid flowers. These results demonstrate the ecological importance of mosquitoes beyond operating as disease vectors and open the door towards understanding the neural basis of mosquito nectar-seeking behaviors.
