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.

Traditional rodent management tools, such as traps and lethal rodenticides, are acute measures to reduce commensal rodent populations. Given the growing concerns regarding effectiveness, environmental safety, and animal welfare related to these tools, it has become imperative to find new methods. Fertility control is an emerging potential alternative to these tools as a safe, humane and effective method of long-term population management. SenesTech, Inc. has developed a liquid fertility management bait that causes follicle depletion in the ovaries of female Sprague Dawley rats and compromises sperm production in male Sprague Dawley rats in laboratory settings. These studies have shown significant decreases in litter sizes following bait consumption, but acceptance of this bait by wild rodents needed to be confirmed. Bait acceptance was tested within refuse rooms of the New York City subway system. Bait was provided ad libitum for 90 days. Uptake was evaluated by examining, via fluorescence microscopy, the presence of the bait marker rhodamine B, which manifests as fluorescent bands in whiskers. Presence of these bands indicated that 51% of the captured population had consumed the bait, and of these, 58% had taken the bait more than once. These results demonstrate that wild rats will consume a liquid fertility management bait, even in the presence of highly palatable and abundant food within the refuse rooms. This study establishes the successful acceptance of a bait by wild rats. Further investigation is needed to evaluate the effectiveness of this product for the management of urban Norway rat populations.

The chemical 4-vinylcylcohexene diepoxide (VCD) induces depletion of primordial follicles in the ovaries of laboratory mice after intraperitoneal treatment and leads to infertility. We assessed the oral uptake of a range of doses of VCD by wild house mice, Mus domesticus, in captivity. In Experiment 1, female mice (n = 8 per group) were presented with a daily dose of liquid emulsion containing different concentrations of VCD in a volume equivalent to 10% body weight for 5 days in the presence of ad libitum mouse chow and water. Body weight, body condition, and general health status of the mice were assessed daily. Mice were killed 17 days after cessation of dosing. Internal organs were examined for normality and ovaries were fixed for analysis of primordial follicle populations. Over the 5-day treatment period, 95-100% of mice consumed all their daily dose of VCD emulsion. There were no effects on body weight, general activity, or alertness of the mice. Primordial follicle populations showed dose dependent but variable levels of depletion. In Experiment 2, the highest, most palatable VCD dose (300 mg VCD/kg) or a control dose was presented to mice (n = 24-30 per group), daily for 5 days. At 10 days post treatment, males were introduced for 3 breeding rounds. The numbers of pups/litter and proportions of females producing litters for each breeding round was not different between groups. In Experiment 3, male mice were presented with this same VCD dose; assessment of their reproductive status at 7 and 15 days post treatment indicated no treatment effect on testis and epididymis weights. These experiments indicate that while some follicle depletion was achieved in females with the orally delivered VCD dose, this was insufficient to affect their fertility. Further studies will require presentation of higher doses of VCD and/or extended presentation of this chemosterilant.

California Assembly Bill 1788 and establishment of the California Ecosystems Protection Act indicates the evolution of public opinion regarding rodent management products is moving away from the use of poison. Similar actions have taken place in the province of British Columbia and the state of Massachusetts, with initiatives in the states of Washington and Connecticut. These events signal a trend in pest management that requires attention. There are many aspects of California’s law that will require further refinements such as enforcement, best practices, and the economics of the action. The FYXX foundation 501c(3) non-profit organization has undertaken to assess these elements of alternate rodent IPM programs including any offsetting benefits of public and employee perceptions. Data was collected from three sites: two animal sanctuaries and a large commercial business district. Strategies were as follows; site #1, an IPM program including exclusion, fertility control, repellents, station monitoring with relocation and reduction (98% population reduction); site #2 IPM including fertility control, monitoring and station relocation, (80% population reduction) and site #3, IPM including station lure baiting followed by targeted fertility control, and monitoring (91% population reduction). All data were analyzed with review by professional pest managers, facility management personnel, municipal agencies, and FYXX staff. Employee interviews and surveys indicated that there was a skepticism at initiation of the study, however, by month #3 a reversal to strong support for the new program and high satisfaction with a poison-free facility. These data indicate that collaborative work between product manufacturers, professional pest managers, and users can provide new alternatives to IPM programs that are economically sound, socially, and politically responsive to a new trend in pest management.

Norway rats cause extensive crop loss, infrastructure damage, and are vectors for zoonotic diseases. Due to growing efficacy, environmental, and animal welfare concerns related to traditional pest management tools, it is important to find new methods for controlling commensal rodents. Fertility control is emerging as a safe, humane, and effective method of long-term pest population management. SenesTech Inc. has developed an oral, liquid fertility management bait with two active ingredients: 4-vinylcyclohexene diepoxide (VCD) and triptolide. Previously, a 95% reduction in pups was observed through three breeding rounds when wild-caught Norway rats were caged in pairs and offered this bait for 50 days. Following these results, wild-caught Norway rats (n=6 males; n=15 females per group) were placed in open arenas, offered bait (in the presence of rat chow and water) ad libitum for 56 days, and allowed to breed for four rounds. Animals were bred within their treatment paired groups (control or treatment) for the first three rounds and then treatment cross-bred during the fourth round. Through three breeding rounds, 255 pups were born to control breeding pairs, compared to 12 pups born to treated breeding pairs. In the final round, 93 pups were born to control females paired with treated males and 80 pups were born to treated females paired with control males. A significant reduction in epididymis weight, and in testis weight and volume, was observed in treated males, while ovarian weight was reduced in treated females. These results indicate that fertility was dramatically reduced in wild caught Norway rats after consuming fertility management bait. Rats voluntarily consumed the treatment bait, and this free selection is essential for future field trials where the ability of the bait to reduce wild rat populations will be assessed in agricultural and urban settings.

Superior rodent management is critical to preserve the diversity of wildlife, and to mitigate environmental and social damage. Pest management strategies can employ 21st century methods to balance the human-animal conflict, especially regarding rodents. Non-toxic fertility control has several advantages over the use of poison when the following parameters are true: 1) rate of removal exceeds rate of population increase; 2) compounds do not bioaccumulate in the rodents or the environment; 3) non-lethal method targets both males and females; 4) animals can be detected at low densities; 5) cost analysis favors fertility control over lethality; 6) method has socio-political acceptance. Our fertility control system meets each of these requirements. Utilizing plant-root-based extracts from Tripterygium wilfordii Hook F, we have formulated a proprietary rodent feed pellet that is efficacious in reducing mice and rat populations in multiple settings. The pellets target rodents with a population reduction capacity of 98% that is sustainable over 12 months. The cost of the pellet solution is less than 90% of other fertility control products, and less than 47% of poison products. The functional key to the success of fertility-control approaches is optimizing feeding protocols to achieve maximum population reduction. We have developed an application-based system to provide sustainable cost-effective management. The monitoring system captures consumption and feeder service data. Point-of-entry data validation is enforced. Compliance with the service program is monitored and configurable alerts are issued for outlying events. These data are ingested into a data analytics engine which generates real-time dashboards for oversight and analysis. Administrative features provide user management, project definition and configuration. In-line instructional documentation and pellet supply order forms provide support for field technicians. As a 501(c)3 non-profit charity we are funded by Open Philanthropy to provide the rigorous data sets presented: a 21st century solution to rodent management.