DEET repels ORNery mosquitoes

Abstract

DEET ([N-N]-diethyl-m-toluamide) is widely used around the world as a repellent for mosquitoes and other biting insects. It was originally identified by a structure–activity study using synthetic compounds (1). Recently, a number of new compounds with similar activity [e.g., picaridine (2)] have been identified, but DEET remains the gold standard. Despite a tremendous number of studies (3), however, a plausible and evidence-based mechanism for DEET's action has remained elusive. In a recent study, Ditzen et al. (4) wrote, “Here we show that DEET blocks electrophysiological responses to olfactory sensory neurons to attractive odors in Anopheles gambiae and Drosophila melanogaster” (Fig. 1A). However, in this issue of PNAS, Syed and Leal (5) present a new mechanism that demonstrates that mosquitoes detect DEET by means of olfaction and that this is the direct cause of their avoidance behavior (Fig. 1B).