RT Journal Article SR Electronic T1 Semi-field evaluations of three botanically derived repellents against the blacklegged tick, Ixodes scapularis (Acari: Ixodidae) JF bioRxiv FD Cold Spring Harbor Laboratory SP 2022.01.12.476114 DO 10.1101/2022.01.12.476114 A1 Xia Lee A1 Colin Wong A1 Joel Coats A1 Susan Paskewitz YR 2022 UL http://biorxiv.org/content/early/2022/01/13/2022.01.12.476114.abstract AB Three compounds derived from botanicals sources, ethyl perillyl carbonate, geranyl isovalerate, and citronellyl cyclobutane carboxylate, were tested for repellent activity against Ixodes scapularis Say in a semi-field trial. Tick drags were treated with the compounds or with N, N-diethyl-m-toluamide (DEET) at high (0.25mg/cm2) or low (0.15mg/cm2) concentrations. Negative controls included untreated drags and drags treated with acetone, the carrier for all repellents. Freshly treated drags (within 20 minutes) were used to collect I. scapularis ticks at a county park in Wisconsin. To assess effectiveness, we measured tick encounter rates, detachment rate, and time to detachment. None of the repellent treatments resulted in significantly fewer encounters compared to both control treatments. However, the percentage of ticks that detached within 3 min was significantly higher on drags treated with repellents compared to controls. DEET was the most effective, repelling 69.7 - 87% of ticks by 3 min, but the effectiveness of the three test compounds was still high, ranging from 42% to 87% of ticks detaching by 3 min. For time to detachment, there were no significant differences between DEET and the three test compounds. We conclude that these botanically-derived repellents were effective against I. scapularis in a semi-field trial and could be viable alternatives to DEET.Competing Interest StatementThe authors have declared no competing interest.