Sprague Dawley Female Rat Consumption of a Liquid Bait Containing Vinylcyclohexene Diepoxide and Triptolide Leads to Subfertility

Abstract

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. Proc. 26 th Vertebr. Pest Conf. (R. M. Timm and J. M. O'Brien, Eds.) Published at Univ. of Calif., Davis. 2014. Pp. 386-390.

Liquid Fertility Management Bait Uptake by Urban Rats within New York City Subway Refuse Rooms

“…Studies have also demonstrated a reduction in litter sizes in the first breeding round with baited females and unbaited males (Dyer and Mayer 2014). A more recent study showed males and females consumed approximately 4% and 10% of their body weight, respectively, and no females delivered litters in the first breeding round (Dyer and Mayer 2014). These results confirm FMB is palatable to Sprague Dawley rats and effective in reducing litter size; however, these results can only suggest how wild rats might respond to FMB.…”

“…In males, FMB targets the number of epididymal sperm and sperm mobility (Liu et al 2010, Xu andZhao 2010). Laboratory studies have confirmed that FMB is highly palatable; both sexes will consume approximately 10% of their body weight while in the presence of ad libitum rodent chow and water (Dyer and Mayer 2014). Studies have also demonstrated a reduction in litter sizes in the first breeding round with baited females and unbaited males (Dyer and Mayer 2014).…”

“…Laboratory studies have confirmed that FMB is highly palatable; both sexes will consume approximately 10% of their body weight while in the presence of ad libitum rodent chow and water (Dyer and Mayer 2014). Studies have also demonstrated a reduction in litter sizes in the first breeding round with baited females and unbaited males (Dyer and Mayer 2014). A more recent study showed males and females consumed approximately 4% and 10% of their body weight, respectively, and no females delivered litters in the first breeding round (Dyer and Mayer 2014).…”

“…In an attempt to establish more humane approaches and improve the quality of human life, SenesTech, Inc. (Flagstaff, AZ) has developed and tested a liquid fertility management bait (FMB) on Sprague Dawley laboratory rats. The active ingredients of FMB, 4-vinylcyclohexene diepoxide and triptolide, target the reproductive systems of males and females, rendering both sexes sub-fertile (Dyer and Mayer 2014). In female rats, all follicular stages of the ovarian cycle are targeted, degenerated, and reabsorbed; therefore, eggs do not mature and ovulate (Lue et al 1998, Flaws et al 1994, Huynh et al 2000, Mayer et al 2002.…”

A roadmap for urban evolutionary ecology

“…This outcome has already been observed in the case of resistance to warfarin(Rost et al, 2009), but may also be problematic with new control methods. For example, many cities have conducted experimental trials of chemical sterilization baits that operate on both males and females(Dyer & Mayer, 2014). Such strong selection acting directly on reproduction could favor individuals with heritable bait aversion and/or biochemical resistance to the compound.Population genetic analyses have also played a role in understanding commensal rodent movements and spatial extent of rat populations, with many potential applications to better target pest management efforts.…”