Evaluation of three recently developed repellents against the blacklegged tick, Ixodes scapularis

Exposure to blacklegged ticks, Ixodes scapularis, commonly occurs in a variety of habitats including recreational forest and residential yards. Picaridin, DEET and permethrin are some active ingredients commonly found in commercially available repellents against ticks and other biting arthropods. Products containing DEET are amongst the most widely used against ticks but DEET is a plasticizer that can damage a variety of plastics which makes it use undesirable for some. The purpose of this study is to evaluate three molecules derived from botanicals that have shown to be efficacious against I. scapularis in laboratory trials. Semi-field trials were conducted in an area of high tick densities and three molecules recently developed as repellents, ethyl perillyl carbonate, geranyl isovlerate, and citronellyl cyclobutane carboxylate, were tested during the month of peak nymphal activity in Wisconsin. Four plots were established in a mixed hardwood forest with each plot containing six subplots randomly assigned to one of the following treatment group: two negative controls, one positive control (DEET), and one of the three repellents. Tick drags were coated appropriately based on treatment assignment and pulled through the vegetation. Ticks were checked after 10 meters and drags were observed for another 3 minutes and all ticks that dropped off were recorded. Here we report on the results of this semi-field trial.