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Open Access Publications from the University of California

ContraPest®, a New Tool for Rodent Control

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Lethal rodenticides and other lethal tools of managing commensal rodent populations long-term are not sustainable due to population rebounds and increasing resistance to rodenticides. The use of integrated pest management (IPM) programs are more prevalent due to consumer desire to decrease rodenticide use and utilize environmentally friendly, humane methods. IPM plans often require multiple tools to control an infestation, such as physical, biological and chemical measures. Here, we propose that rodent population management would benefit from a new tool aimed at targeting the biological source of overabundance: reproduction. SenesTech, Inc. (Flagstaff, AZ USA) has developed ContraPest®, a liquid bait that limits the reproductive capacity of both male and female wild Norway and Roof rats. The two active ingredients, 4-vinylcyclohexene diepoxide (VCD) and triptolide, deplete all stages of follicles in the female and disrupt spermatogenesis in the male. Laboratory and field studies reveal that ContraPest® is palatable and repeatedly consumed by rats even when provided with ad libitum food and water. Studies involving laboratory and wild caught rats have demonstrated a 93 - 100% reduction in litter sizes of rats treated with ContraPest® compared to control rats. ContraPest® was tested on free ranging rat populations in agricultural and urban settings. Rat populations on protein production farms decreased by an average of 46% following 100 days of treatment with ContraPest®. In a complex urban environment, where property boundaries limit access to populations and foraging areas, ContraPest® reduced the seasonal population peak by 67% after 133 days of baiting. These studies, combined with all of our field studies and population reduction models, demonstrate that ContraPest® is a highly effective rodent contraceptive bait in a variety of environments. We strongly believe that adding/implementing fertility management via ContraPest® to an IPM program would enhance long-term rodent population control in rural, urban, and agricultural environments.

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