First Report of the Repellency of 2-Tridecanone in Ticks

Abstract

The chemicals 2-tridecanone and 2-undecanone are both found naturally in the trichomes of wild tomato plants and are important in plant resistance to herbivory. 2-Undecanone recently was shown to be an effective tick repellent and is the active ingredient in the commercially available arthropod repellent, BioUD®®. The goal of this study was to examine, for the first time the, tick repellency of 2-tridecanone. Two-choice bioassays were conducted between 8% 2-tridecanone versus the repellent carrier, absolute ethanol and compared to similar choice studies with 8% 2-undecanone versus absolute ethanol. Unfed, host-seeking adult (mixed sexes) Amblyomma americanum and Dermacentor variabilis were used to evaluate repellency and time to repellent failure at room temperature on two different substrates. In filter paper assays, 2-Tridecanone was >70% repellent to A. americanum and D. variabilis for 12 and 15 h, respectively. In contrast, 2-undecanone was >70% repellent to A. americanum and D. variabilis for only 2 h. In two choice assays on cheesecloth, 2-tridecanone was 85% repellent to A. americanum for 6 h. 2-tridecanone provided repellency significantly longer than 2-undecanone. The potential use of 2-tridecanone as a tick repellent is discussed.