Which of the following is a common anti-coagulant used in pest control baits?

Bromadiolone is a commonly used anticoagulant in pest control baits, specifically designed to target rodents. Its mechanism involves interfering with the blood's ability to coagulate, leading to internal bleeding in the target pest. This type of action effectively reduces rodent populations when they consume the bait, as they do not show immediate signs of illness, which allows for a greater likelihood of consumption by other rodents.

In contrast, the other substances listed serve different purposes in pest control. Fipronil is a broad-spectrum insecticide that works by disrupting the nervous system of insects rather than acting as an anticoagulant. Imidacloprid is a neonicotinoid that also targets the nervous system, affecting the communication between nerve cells. Chlorfenapyr is a pro-insecticide that works by disrupting cellular metabolism, not by affecting blood coagulation. Each of these alternatives operates on distinct biochemical pathways, illustrating the specialized use of bromadiolone in the context of anticoagulation.