Insect repellents of natural origin: catnip and osage orange

Abstract

<p>The studies presented here represent my efforts over the last several years to identify naturally occurring insect repellents. Two plants are reported here, catnip and the osage orange. The first study confirmed repellency of osage orange extracts to the maize weevil, but found that repellency to two components, osajin and pomiferin, was not significant. A second study evaluated the effects of catnip essential oil on German cockroaches. Extracts of the plant and isolated compounds were more repellent than diethyl- m-toluamide (DEET). One isomer of nepetalactone was more active than the other was. We determined that the chemoreceptors responsible for the repellent response were located on the antennae. A third study reexamined some of the activity we saw in osage orange extracts in the first study. We examined the essential oils of the fruit, and identified several sesquiterpene compounds. We tested the repellency of essential oil components to German cockroaches, and found several of them to be repellent. In the last study we examined the repellency of catnip and osage orange extracts to the yellow fever mosquito. We determined that catnip essential oil significantly reduced the number of insects near the treated area.</p>