Schematic of the mosquito ear composed of a sound receiver or flagellum, and the auditory organ, the Johnston’s organ at its base. The auditory neurons are ciliated and together with support cells form functional units called scolopidia.

The mosquito auditory organ, the Johnston’s organ, is a highly complex sensory organ located in the antenna. We have recently shown that it is innervated by an efferent system, meaning that the brain controls its function via descending pathways that release different neurotransmitters into the mosquito ear. The efferent control of mosquito audition is a remarkable feature as mosquitoes are the only insect where auditory efferents have been found. Efferent innervation is ubiquitous in the vertebrate ear where it generally controls the auditory sensitivity. In mosquitoes, we have shown that efferent fibres release the neurotransmitters octopamine, serotonin and GABA to modulate the auditory function. Because efferent input has been found in evolutionarily diverse mosquito species, we believe that the efferent innervation is an intrinsic component of the mosquito auditory system that boosts the acoustic sensitivity and plasticity to optimise the detection of the mating partner in the swarm.

In the lab, we are investigating how the efferent neurotransmitters modulate the mosquito auditory function and its implications for mosquito swarming and mating behaviour. We combine genetic and cellular approaches to knock-out the receptors of interest and study its expression pattern. We also perform auditory and behavioural tests to disentangle the action of the efferent input. Our findings will contribute to an improved understanding of the mosquito acoustic responses and, due to the importance of mosquito audition to mosquito reproduction, potentially suggest new targets for vector control.