One of the most important things to consider when selecting a bait is the bait matrix. A bait matrix is the food attractant that draws the pest in or provides the yummy bits for the pest to eat. Nutrition requirements change for pests throughout the year. For example, ants are not that different from humans. They require a diet of proteins, carbs (sugars) and fats in varying quantities to stay healthy. These dietary needs may fluctuate as the seasons do. Additionally, the species of ant will have differences in dietary needs and preferences.
Just as your food preferences change, pests also will shift away from a food matrix that they have liked for extended periods of time. Do you really like to eat the same thing for every meal of every day? Of course not! I love pasta, but there are just some days that I want to choose something else.
Something else that might cause bait aversion are sub-lethal effects. I had a sub-lethal effect with some Mexican food once and it kept me from eating it for a while. Pests are no different. If they get sick from eating a food, they likely will not eat from it again.
It is critical to implement bait rotation into your program. Regularly swapping between active ingredients, and even more importantly the class of the active, is important to prevent insecticidal resistance. Swapping between matrices is equally important to provide for pest nutritional needs, food preferences and to preserve the investment of the manufacturers. If the pests tire from eating the baits, the baits stop working.
Another consideration in product stewardship is the elimination of proactive placements of baits. This is really a core tenant of IPM. If you do not have a pest, what are you baiting for? What species are you expecting? What is driving the choice of bait to use? If you cannot answer these questions, then your bait placement is wasted. Your money is wasted.
A secondary consideration related to product stewardship is that old bait is not palatable to pests. Have you ever been to an account where there is old bait dried up in the cracks and crevices? If pests would not still eat it, why is it there?
This lack of palatability goes back to the first topic, bait aversion. Let’s say I am treating a park local to you and me. I think you might visit it someday, so I leave out a delicious, yet laced-with-a-toxic-product hamburger for you. Even if you come by just a day later are you going to eat it? No! And you don’t even know that it’s toxic! Proactive placements do not work and should be stopped!
I recently took a poll in an online group and asked about bait rotations. I admit, there was not a high response rate. I do not know if that was because people did not see it or if people were afraid to answer the question. But what I found through the responses I got was that people tended to rotate insect baits, but not so much their rodenticides. Rodenticide rotation is slightly different than insecticide rotation, but nonetheless just as important.
There has not been a new active in the rodenticide market in some time, but there are new bait matrices. We, as an industry, seem to rotate baits when we think there might be resistance. Do you have accounts where you have seen a decline in feeding on the exterior stations? Have you considered that the lack of feeding on your baits might be because rodents are choosing to feed on different things and not that you have controlled the populations? Our rodenticide manufacturers invest lots of money into making different types of rodenticides to allow for a proper rotation. The formulation of the blocks (or soft baits) are different. The compositions of seeds, meals and odors are different. The actives are different.
You may be saying right now, “Yeah, but most of what I use is a second-generation bait, so switching actives to another second gen won’t help!” You would be incorrect. Even between the different actives there are slightly different receptors in the rodents that will make a difference in your results. Do not forget that there are other options as well. There are still first-generation products and non-anticoagulants available to mix into rotations if needed.
Each product that is passed down to us from a manufacturer is a $286 million gift. We as industry professionals have a duty to protect those gifts for as long as possible. One of the easiest methods is by rotating products. Keeping a rotation plan in place prevents pests from growing accustomed to any bait matrix. Consider a quarterly rotation to get started.
If we as an industry do not protect these products, we will either continue to lose tools from our toolbox, or the cost of our products will continue to rise.