ARS | Publication request: Development of novel tropical and spatial repellents

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: February 6, 2013
Publication Date: N/A

Technical Abstract: The United States Department of Agriculture (USDA) has examined over 30,000 repellents and insecticides for the U.S. military since 1942. In the past few years, sophisticated in silico approaches have been used to model the correlation between a subset of similarly structured chemicals from this archive and link the structures to the experimentally determined repellency. This approach has led to the discovery of new compounds with better repellency. Repellency is usually measure either in terms of duration, i.e. complete protection time (CPT) or minimum effective dosage (MED). The MED is an estimation of the threshold surface concentration at which a repellent fails or drops below the effective dose for 100% bite prevention (ED100). While the US Environmental Protection Agency (US EPA) requires CPT for registration of repellent products, we primarily assess the MED of compounds rather than the CPT. Collaborative efforts with other USDA laboratories are aimed at developing repellents from natural products. These plant-produced extracts and compounds usually more volatile than synthetic repellents and therefore will not persist as long on the skin. Because of the volatility of these compounds, they are also good candidates for “spatial repellents” or “inhibitors.” Inhibitor chemicals mask the detection of odors rather than producing repellency which causes insects to move away from the source of the repellent. Some spatial repellent products on the market that contain natural products such as geraniol and linalool; however, none of these cloak (human) hosts as well as a class of nitrogen-containing heterocycles. These compounds offer a non-toxic alternative to personal protection from mosquitoes and other biting arthropods. This presentation will cover the USDA efforts to discover new synthetic and natural product topical repellents, and the discovery of chemicals make hosts invisible to arthropods.