Proceedings of the Vertebrate Pest Conference

Worldwide, Norway rats cause significant infrastructure damage, agricultural losses, and carry zoonotic diseases. Due to rat fecundity, killing them by mechanical and/or poison does not lead to sustainable management of their populations. Our biotechnology company, SenesTech, Inc, has developed an environmentally safe oral bait taken by rats, causing them to produce fewer rat pups and take longer to deliver, without any observable adverse effects. The fertility control bait is an emulsion and contains two chemicals that cause ovarian follicle elimination; vinylcyclohexene diepoxide (VCD) targets the finite pool of primordial/primary follicles, and triptolide (T) targets growing follicles. Female Sprague Dawley rats were 33 days old when provided bait with 0.1% VCD and increasing amounts of T with unlimited chow and water for 15 days (n = 8 rats per group). The rats consumed >5% of their body weight of bait and thrived during their rapid growth phase. The day after the end of baiting, female rats were bred with untreated, proven male breeders for 21 days, then litter size and time to delivery was tracked over the next 25 days. The control group that consumed bait without active ingredients had an average litter size of 11.5 pups, treatment groups that consumed bait with T at 400, 800, or 1200 μg/kg body weight had average litter sizes respectively of 9.6, 8.3, and 3.6, and pup production per treatment group compared to control group was 83.5%, 72.2%, and 29.6% respectively with increasing T doses. Time to delivery increased significantly as T dose increased: control rats took 26.0 days versus 31.5, 38.9, and 38.2 days to delivery. We conclude our fertility control bait is a palatable liquid readily consumed by growing female rats that causes subfertility, with significantly fewer pups/litter taking 1.5 times longer to deliver. Fertility control bait effects on rat population dynamics are currently being tested in field locations.