Contrary to popular belief, rodents, particularly rats, will not voluntarily eat inferior or spoiled food when other enticing options are available. Rodenticide efficacy relies on the target rodents voluntarily eating enough bait. Therefore, preventing access to preferred food sources (grain) is essential to improving the acceptance of rodenticide bait. Where possible, feed should be housed in secure, sealed containers. For effective control through baiting, users must identify the rodent species they are dealing with (see Rodent species) and identify active compounds that will be effective (Table 16).
Most active rodenticides will be found in many commercial products. Bait manufacturers combine the active ingredients with unique proprietary blends of non-hazardous ingredients to make baits palatable and enticing to rodents. While this review does not endorse the use of specific trade name rodenticides, users can experiment with commercial baits to identify products that target rodents accept more readily. A simple choice of feeding can be tested by placing identical amounts of different commercial baits in bait stations in areas where rodents are active and then monitoring the amount of bait taken to identify palatable products. Rats specifically are neophobic, which means they are suspicious of new objects and novel foods. Therefore, users should be mindful that rats might not accept a new bait for several days.
Rotating different baits may maintain their palatability and acceptance. Frequent rotation may have the opposite effect, particularly with rodents that are constantly suspicious of new and different food items in their environment. There is no scientific evidence to suggest that rotating bait products will prevent the development of anticoagulant resistance because all anticoagulant compounds share an identical mode of action. Rotating baits with different chemical modes of action (e.g., anticoagulant to cholecalciferol) could reduce the development of resistance (Buckle and Prescott, 2012).