Gustatory receptor neuron responds to chemically diverse insect repellents in the common malaria mosquito Anopheles quadrimaculatus

Authors: SPARKS, JACKSON - Former ARS Employee; Dickens, Joseph

Submitted to: Naturwissenschaften
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/15/2016
Publication Date: 4/23/2016
Citation: Sparks, J., Dickens, J.C. 2016. Gustatory receptor neuron responds to chemically diverse insect repellents in the common malaria mosquito Anopheles quadrimaculatus. Naturwissenschaften. 103:39.

Interpretive Summary: Insect repellents provide protection from diseases vectored by mosquitoes by reducing contact between mosquitoes and their human hosts. Here we show that a taste receptor in the common malaria mosquito is broadly sensitive to feeding deterrents as well as naturally occurring and synthetic insect repellents. The mode of action of all repellents involved stimulation of the receptor for feeding deterrents and inhibition of the receptor for a feeding stimulant (i. e. sugar). Synthetic repellents including DEET had a third mode of action that involved nonspecific bursts of neural activity from the taste receptors. Knowledge of the mechanisms by which repellents are detected may be used by entomologists and molecular biologists to evaluate chemicals for repellent activity in an effort to discover novel or improved chemicals for protection of humans and animals from disease vectors.

Technical Abstract: Female mosquitoes feed on blood from animal hosts to obtain nutritional resources used for egg production. These contacts facilitate the spread of harmful human diseases. Chemical repellents are used to disrupt mosquito host seeking and blood feeding behaviors; however, little is known about the gustatory sensitivity of mosquitoes to known repellents. Here, we recorded electrical responses from gustatory receptor neurons (GRNs) housed within labellar sensilla of female Anopheles quadrimaculatus to N,N-diethyl-3-methylbenzamide (DEET), picaridin, IR3535, 2-undecanone, p-menthane-3,8-diol, geraniol, trans-2-hexen-1-ol, quinine and quinidine. A bitter-sensitive GRN responded to all tested repellents and quinine, a known feeding deterrent. Responses of the bitter-sensitive neuron to quinine and an isomer, quinidine, did not differ. Delayed bursts of electrical activity were observed in response to continuous stimulation with synthetic repellents at high concentrations. Electrophysiological recordings from bitter-sensitive GRNs associated with mosquito gustatory sensilla represent a convenient model to evaluate candidate repellents.