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Title: Electrophysiological responses of gustatory receptor neurons on the labella of the common malaria mosquito Anopheles quadrimaculatus Say (Diptera: Culicidae)

Author
item Sparks, Jackson
item Dickens, Joseph

Submitted to: Journal of Medical Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/20/2016
Publication Date: 5/11/2016
Citation: Sparks, J.T., Dickens, J.C. 2016. Electrophysiological responses of gustatory receptor neurons on the labella of the common malaria mosquito Anopheles quadrimaculatus Say (Diptera: Culicidae). Journal of Medical Entomology. doi: 10.1093/jme/tjw073.

Interpretive Summary: Insect repellents reduce contact between mosquitoes and their human hosts, thus providing protection from diseases vectored by mosquitoes. Here we report the discovery of a taste receptor in the common malaria mosquito that responds specifically to a feeding deterrent and the insect repellent DEET. Other taste receptors responded to salt and sugar. DEET’s mode of action involved both stimulation of the feeding deterrent receptor and inhibition of the sugar receptor. This is the first report of a specific taste receptor for feeding deterrents in a malaria mosquito. Knowledge of the mechanism by which DEET has its effects may be used by entomologists and molecular biologists to screen chemicals in an effort to discover novel repellents for protection of humans and animals from disease vectors.

Technical Abstract: We recorded electrical responses from sensory cells associated with gustatory sensilla on the labella of female Anopheles quadrimaculatus to salt, sucrose, quinine (a feeding deterrent) and the insect repellent, N,N-diethyl-3-methylbenzamide (DEET). A salt-sensitive cell responded to increasing concentrations of sodium chloride. A second cell was activated by increasing sucrose concentrations, while quinine, DEET or a mixture of quinine + DEET elicited spike activity from a third cell, an apparent bitter/repellent-sensitive cell. Both quinine and DEET suppressed activity of the sugar-sensitive cell; sucrose suppressed activity of the bitter/repellent-sensitive cell. These results demonstrate separate gustatory pathways for a feeding stimulant and aversive contact cues mediated through distinct sensory inputs on the labellum. This sensory appendage may serve as a useful target to disrupt feeding behavior in this and other Anopheline species, which transmit diseases like malaria to human populations.