Efficacy of the new repellent BioUD against three species of ixodid ticks

BioUD® with the active ingredient 2-undecanone originally derived from wild tomato plants is a new repellent recently registered by the US EPA. Repellent efficacy of BioUD® (7.75% 2-undecanone) and DEET (98.11%) was examined in the laboratory using a choice test between repellent-treated and control filter paper surfaces for Amblyomma americanum, Dermacentorvariabilis, and Ixodesscapularis. BioUD® provided greater repellency against A. americanum and I. scapularis than DEET. No difference was found between BioUD® and DEET against D. variabilis. In head-to-head assays between BioUD® and DEET, undiluted and 50% dilutions of BioUD® were more repellent than undiluted DEET against all three species tested. Similarly, a 25% dilution of BioUD® was more repellent than DEET against A. americanum while no difference in mean percentage repellency was found between a 25% dilution of BioUD® and DEET against I. scapularis. Based on regression analysis, the concentration of BioUD® required for equivalent repellency to 98.11% DEET was 39.5% for D. variabilis and 29.7% for I. scapularis. A log-probit model could not be constructed for A. americanum from the dosages tested. Based on filter paper head-to-head assays, BioUD® is at least 2–4 times more active as a repellent than DEET against three species of ixodid ticks under the conditions of our laboratory bioassays.