Rodent Fertility Control: What It Is and Why It’s Important

Rats reproduce at an extremely rapid rate. Under ideal conditions, two mating rats can be responsible for 15,000 descendants in one year, which makes infestations difficult to eliminate. How can fertility control products help eliminate rats?

Rats reproduce at an extremely rapid rate. Under ideal conditions, two mating rats can be responsible for 15,000 descendants in one year, which makes infestations difficult to eliminate. While one of the most common methods of control is the use of rodenticide baits, it’s no secret that pests can evolve to become resistant to pesticides and rodenticides, requiring increased concentrations or combinations for efficacy. While there have been attempts to reduce the need for these by introducing sterilized males into populations, according to a study by Stephen M. Shuster, et al, ( too often the females will discriminate against treated males. Thus, “pest control measures that reduce fertility, rather than those that cause sterilization or death in pests, are likely to be most effective in slowing the evolution of treatment resistance” – particularly methods that work against both sexes.
But, he states, that means changing the goal of pest control treatments. Instead of attempting to eliminate an entire population, PMPs can use such contraceptives to reduce the rodents’ rate of reproduction, then, because the rodents are now sterile, rodenticides can be used to eliminate the population without the fear of resistance evolving in offspring.
Effective Control. That was just the method that Missouri Pest Consultants Owner Terry Hoselton employed to eliminate a rat infestation at St. Louis’ Kiener Plaza at the foot of the Gateway Arch. The city was conducting an expansive renovation of the park, but with the continually growing rodent population which had climbed to more than 400 with more than 70 active burrows, “it had turned into a $25 million rat condo!” he said.
But with the 1.9-acre park being a hub of the city – holding parades and concerts and attracting families with its playground, splash pad, shade garden and picnic areas, “it was a logistical nightmare for rodent baiting,” Hoselton said. “But we had to do something drastic; we had to get it under control.”
So Hoselton turned to a rodent contraceptive. “We installed fertility control up front. We made everyone clean up so the rats had no choice to eat anything else. They took to it fast.” After about three weeks, the population had stabilized, so Hoselton took the next step, with secured rodenticide bait placements. He left that in place for six months, as the rodent population decreased to zero, the desired wildlife – bunnies and birds – began to return.
Non-toxic Control. As a former co-owner of American Pest Control, Becky Wade has had a large number of clients opposed to the use of toxic baits because of their pets or concern for secondary kill of wildlife and birds. But, she said, “We had a number of clients where correcting conditions conducive or combating neighbors with those conditions was a losing battle. Traditional bait and treating of burrows become maintenance over years without a real resolution.”
One customer in particular had a significant rat infestation, but had had a deadly experience with rodenticides she was adamant against their us. Additionally, rats were such a problem in the county that a homeowner could be reported to the county and required to show proof of rat control. Thus, fertility control was the only measure she would consider. Having not worked with the product in the past, Wade donated her services as a certified applicator, offering no guarantee of success. But it worked – fertility control alone eliminated the problem.
Wade also used fertility control at an apartment complex where bait stations and burrow treatment program had been in place for 10 years. But with a creek running through one side of the property, a shopping center with a number of restaurants on another, the environment was extremely conducive to rodents. So birth control stations were installed, sometimes side by side with rodenticide stations, she said, adding, “Both were consumed but the reduction is complaints/sightings occurred after the addition of birth control stations.” And after two months, rodents did not even appear on their list of pest problems. 
Humane Control. “I was surprised to see that so many people would rather live with or ignore a Roof Rat infestation, than to kill or rid them from their premises,” said Avant-Garde Pest Management President Mick Fetty. He also has learned that the client who prefers fertility interruption methods does not mind the increased cost as opposed to trapping, exclusion and rodenticides. “This method is especially appealing to those who prefer humane non-lethal management,” he said.
Humane management is also a key reason for some who want to protect desired wildlife, with the protection of all life a primary reason for some. Rodent fertility control is the preferred method of Wildhorse Ranch Rescue Founder Kimberly Meagher because it’s humane. “Being animal rescue people, we value all lives, not just certain ones,” she said. “We have never killed or poisoned the rodents at Wildhorse Ranch Rescue.”
Prior to learning of the availability of fertility control, the ranch was humanely trapping and relocating the rodents, she said. “This is a lot easier for our management team.”
The ranch also rejects use of any toxic product on the property, because there are many animals at the ranch that it would not want exposed, directly or indirectly. One example Meagher gave is that of a cat from the neighborhood who visits regularly and occasionally hunts for rodents. “If he got hold of a poisoned rodent, it could be detrimental to his health as well,” she said.
Innovative Control. Hazelton sees a great deal of potential for fertility control in the pest industry. “If it gets labeled for mice, it’s going to be good for the industry,” he said. “But the industry has to give it a chance."

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