Stephen Vantassel here So those are the two main categories of rodenticides we have the anticoagulant non-anticoagulant and then underneath the anticoagulant rodenticides we have first generation anticoagulant rodenticides and we have second-generation anticoagulants rodenticides and Il talk a little bit about LD 50 and then some of the pros and cons of first generation and second generation anticoagulants.
Rodent Pest Control
[00:00:01] Stephen Vantassel here wildlife control consultant bringing you another episode the wildlife one to talk today a little bit about toxicants. Toxicant are basically poisons that are used to control various types of past organisms. So because I am my specialty as vertebrates of course. So we’re going to talk about rodenticides primarily because rodents are a significant source of pests. That Affect impact human health and Structures and safety and sometimes are just a nuisance but they can be a significant problem.
[00:00:45] We’ll talk about understanding rodenticides. So we’re going to take a little bit of time and do a little bit of overview and then in future podcasts I want to drill down into specific active ingredients so that we have a better understanding of what we’re using. And in how sometimes we’re not using it really the way we should be using them. So hopefully this will help you become a better PCO or wildlife control operator. A lot of wildlife control operators don’t have pesticide licenses. I think that’s a mistake even if you don’t plan on using toxicants right now as a part of your business. I encourage all wildlife control operators take take time take the effort get your pesticide license so at least you can do use rodenticides around structures because you never know there are going to be situations where rodenticides can help your business I have a colleague who makes a significant portion of his income in the wintertime when things are slow where he lives he lives in kind of the frozen. Frozen North there’s tons of snow and he keeps his business going just money just for refilling bait stations during the wintertime for clients who are having issues with voles and other another rodents that are around structures so it can be a way to help your business and in a different to generate revenue without always having to trap or exclude.
Two Main Types Of Rodenticides Baits In Rodent Pest Control
[00:02:21] So let’s talk a little about rodenticides. So a rodenticides of course are toxicants pesticides that kill rodents so rodent. When knows what that word means and cide means to kill. So these are products they’re designed to kill. Rodents. So let’s talk about the major categories of rodenticides. So when we’re talking about baits these are things that are consumed by rodents. They fall into two major categories anticoagulants and non anticoagulants. So anticoagulants as the name suggests fights the coagulation of our blood. So these are products that cause the capillaries and the coagulated factors in blood to break down and no longer work so that the rodents are suffering from hemorrhaging which is a fancy word for bleeding and they’re often bleeding internally at the at the vascular level. Occasionally you will see blood coming out in their stool or through their orifices like their nose although that’s not that’s not very common. They’re made maybe some bloody some bloody stool. A lot of the bleeding that occurs is at the vascular level in their capital areas which are really tiny veins and arteries. It’s a capillaries our last. Spot to where the blood goes till it reaches the cellular level and that’s where the breakdown often occurs.
[00:04:00] So if you cut one of these animals open make sure you’re wearing your PPE Of course you will just see massive red because the blood is just going everywhere in that organism’s body.
[00:04:16] The other category of rodenticides is the non anticoagulant and so the the mode of action that is how the product kills uses uses a means that that’s not related to the coagulation of blood and that is going to vary depending on the product. So it’s basically a garbage can categories. So either it causes bleeding. In the organism as the anticoagulants do or it kills by another means and there are several means that it uses.
[00:04:50] So let’s talk briefly about those cats. But the individual products. We’re talking only about the active ingredients here are not specific brand names. OK. That can be may be for a later conversation but we’re just talking about the active ingredients that are used in the right and the. So let’s talk about the anticoagulants first within the category of anticoagulants. There are two other categories. That subdivide the category of anticoagulant and that is known as first generation anticoagulant rodenticides with the acronym FGAR for first generation anticoagulant rodenticides and then of course if you have first then you’d likely have a second. Then you have the SGARS. That’s the second generation anticoagulant rodenticides.
Understanding First Generation Vs Second Generation Anticoagulant Rodenticides
[00:05:44] So the two we have rodenticides. Then two subcategories anticoagulant non anticoagulant. Now within the anticoagulant category it breaks down into two further categories of first generation anticoagulant rodenticides and second generation anticoagulant rodenticides. So let’s talk about those specific products within those particular categories. So within the first generation anticoagulant these are they’re called first generation because they are generally older. Than the second generation. These products are called out the names are warfarin Chlorophacinone and Diphacinone.
[00:06:29] So warfarin is one of the oldies it was it base it’s even used on humans today in terms of trying to keep our blood thin when people are having issues with clotting maybe that stroke or heart condition where they need to stop. Reduce the clotting factor of a person’s blood. So it’s you know we people call it all you’re taking rat poison. Yeah it’s kind of everyone laughs and it’s kind of true because remember the dose makes the poison so in small quantities under physician direction warfarin is is an important medicine. Actually it’s used to help people extend their lives and improve their wellbeing. But when we use it for as a rodenticide it is used to kill rats and mice as they’re consuming it. So warfarin is an old one Chlorophacinone produced by used by liphatech. They use a lot of products from warfarin that’s also a first generation anticoagulant and of course Diphacinon which is used often by side metrics out of Colorado that is also a first generation anticoagulant.
[00:07:38] So what are some of the characteristics of first generation anticoagulants first generation anticoagulants are known as multi feed toxins. What that means is is that the role the rodent has to feed on the product multiple times in order to take to get a toxic dose now that may seem counterintuitive to say why do we want to use a product where the rodent has to eat more in order to get a toxic dose. Well understand if if the product takes more time to kill the animal. Than the animal doesn’t it’s less likely to get what’s known as aversive conditioning. So for example aversive conditioning means that if you eat something and it makes you sick you often avoid that particular food group again for example if you went to a restaurant and you ordered a meal and you were throwing your guts up later that night it is very unlikely that you will go back to that restaurant again.
[00:08:52] Why. Because you associated that vomiting experience with your last meal that’s aversive conditioning. So then you learned from that and you have now have aversive conditioning toward that particular restaurant. Well rodents are the same way. If the effects of a rodenticide are too fast.
[00:09:15] The rodent will then learn to avoid that particular product. So with warfarin and Chlorophacinone and Diphacinon the rodent has to feed on it multiple times in order to achieve a toxic dose. Now here’s the interesting thing about rodenticides about these particularly rodenticide and a lot of people don’t quite understand. They are actually more toxic at small doses over time than if you eat a lot at once. Now that’s kind of weird. That’s why would the the product better words if the rat eight a bunch of warfarin at one sitting and then didn’t need any more. It would be harder to kill the rat than if the rat eight a nibble on day one and a nibble on day two and maybe a nibble on day three.
[00:10:15] The answer is yes because the way these products work as they interfere with the clotting factor within the body and if the body is. If you eat too much at once you’re I don’t know maybe your body is some sort of defensive mechanism to it so that it just doesn’t overwhelm as much but a little bit each day is actually more toxic for the rodent than if the rodent. Ate a lot.
Undeerstanding The LD50 In Rodenticdes
Now why is that important to mention because this is the problem when we look at what’s called the L.D. 50. Now a lot of you are probably familiar with ld 50 it’s the Lethal Dose 50 percent. Now what that means is it’s the amount of material that an animal needs to eat in order for 50 percent of the population the test population to die. Now the the quantity the volume is is evaluated and the basis of a milligram per kilogram. Now we don’t use metric system that much in the United States. So it can be a bit confusing when you hear that what’s a milligram what’s a kilogram well a kilogram is about two point two pounds and a milligram is one millionth. Of a kilogram. So if you take two point two pounds and divided up into a million parts each one of those parts is one milligram. So the ratio that’s used for lv 50 is the ratio of milligrams per kilogram. How many milligrams of toxic and. Does it is needed to kill an animal based on the number of kilograms in that organism at a mill at a ratio of milligram per kilogram. Now obviously. Most rodents are less than two point two pounds.
[00:12:13] So if you’re dealing with something like a rat it’s a pretty big rat to even reach become close to the weight of a pound. So we’re talking about some very small quantities of poison necessary to kill. A particular rodent. That’s why when you look at the active ingredients the active ingredient is point 0 0 5 percent really small quantities and so the rodent doesn’t need to eat that much each day to get a toxic dose. But that ld 50 means that the. But that ld 50 is based on how much that rodent has to eat in one sitting to kill 50 percent of the pot of the test population. So if you have 20 rodents the researchers feed those rodents. A single dose of poison and then they determine and then when they find that 50 percent die they then evaluate how much poison was needed at a ratio of MG to KG to kill that 50 percent of the rodent population. So really really small. Really really small amounts but it’s again a single dose. But when we look at how rodeticide work however we don’t need a single dose. So a little bit of toxicant each day over several days for this first generation anticoagulant is all that’s necessary to kill rodents. Why am I hammering away at this point so hard. It’s because a lot of people think you have to use a second generation anticoagulant to get good control on rodents it’s simply not true. Are there indications. Are there rodents that have are that have resistance to first generation anticoagulants.
[00:14:12] Yes but resistance doesn’t mean immune but I’m gonna put that aside for a moment and get back to that LD 50 again. So the end the ld 50 when they do those tests those are based. Those are what’s called acute poisoning tests how much poisons needed in one dose
[00:14:35] To kill 50 percent the population.
[00:14:38] Now what that also means is 50 percent of the population survive so the ld 50 just gives us sort of an average. There are some problems with that ld 50 ratio but it’s what we have and it’s you just have to understand that it’s there are limitations to it but also that 50 percent of that test population survive.
[00:15:05] So one of the downsides of first generation anticoagulants is that you have to apply more bait to kill the same number of rodents. Why is that. Well because the proteins have to feed on the bait multiple times to get a toxic dose. So one reason why I suspect many PCOS don’t like to use first generation anticoagulants is that they have to check the bait stations more frequently because if the bait stations go empty and the rodent has not consumed enough toxic to get a toxic dose. The rodent will get sick and associate the illness with the fact they’ve been eating that poison. And then you have an educated rodent. So this is why when you read rodenticide labels that using first generation anticoagulants they will repeatedly say Do not let your bait stations go empty. Maintain a sufficient amount of bait in those stations to ensure that you kill the population that you’re trying to kill because if it goes empty and that rodent didn’t eat enough then the rodent will survive. And now you have an educated rodent and I hope as PCOS and wildlife control operators the last thing we want in life is an educated rodent. OK. Because then that becomes very difficult to control. It also takes more time to kill rodents with first generation anticoagulants. You may say why. PCO. My customers want fast service I need to knock this population down immediately. Well I understand that but under. But you also need to understand how much time are you actually saving.
Fast Kill Second Generation vs Slow Kill First Generation Anticoagulants
[00:16:49] One day yeah that’s right. You heard it one day because second generation anticoagulants don’t kill immediately
[00:17:02] And this is the dirty secret that people don’t think about when they think about second generation anticoagulants. So it takes three to four days to kill a rodent with first generation anticoagulants. It takes two to three days to kill a rodent with first generation anticoagulants with excuse me with second generation anticoagulants one day. Big wop. Do you think your client really notices. Now. Not really. So you don’t need to use second generation anticoagulants just for speed purposes. It just doesn’t. It’s just simply not. It’s simply not true. If the rodents are eating the bait the bait is good and the rodents like it. You save about a day the advantage of first generation anticoagulants is that they are safer in terms of secondary poisoning.
[00:18:03] Now a lot of you I’m sure familiar with secondary poisoning secondary poisoning is when the rodent eats the toxicant and then another animal eats the rodent. What is the effect of that poison in that rodent have on the predator that ate the rodent that secondary poisoning research is coming out as finding that the second generation anticoagulants
[00:18:29] Are far more persistent in the pest species and that’s becoming a risk for the scavengers in the carnivores that are eating the rodents. So this is why there is a push for reducing the amount of secondary of second generation anticoagulants in the environment because of how persistent and we’re talking about orders of magnitude more persistent because remember when you take a when a rodent consumes a rodenticide its metabolism is beginning to break that toxicant down first generation anticoagulants are broken down as a rule faster than second generation anticoagulants. So what’s called the half life. How much time is needed to reduce the amount of toxicant in an organism to 50 percent. That’s known as the half life is significantly shorter in first generation than it is for second generation. Second generation anticoagulants the half life half lives can be weeks to months
[00:19:43] Where in first generation anticoagulants the half life is often days two weeks and that’s significant when we’re dealing with secondary poisoning issues. All right.
[00:19:58] Let’s turn over to second generation anticoagulant rodenticides just like the first generation first generation anticoagulant retenticides are multiple feed the other words the rodent has to feed on it multiple times to get a toxicant dose second generation anticoagulant rodnticides only require the rodent to feed once.
[00:20:23] Now you may be thinking that’s what I want. I want the rodent to feed once and he’s dead. Well it’s little more complicated than that because yes one dose for that rodent will give it a toxic dose. However the rodent doesn’t get just one dose because there’s a delay factor for that rodenticide to affect the rodent. So the rodent goes to a second generation anticoagulant feeds on day one has a toxic dose but the effect of that toxic dose doesn’t begin to hit the rodent probably late on day two or late or early in or day three. So what does the rodent do on day two goes back to that particular bait again gets another dose. Now the rodent has. Twice as much toxicant as necessary to kill it. Now what happens in real life as you may know in terms of mice mice will revisit a location and feed multiple times every day. So now the mouse is getting maybe three or four doses of toxicant on day one maybe three or four doses of toxicant on day two and then starts feeling the effects on day three.
[00:21:47] But the rodent has four to six times more toxicant lethal toxin in its body than necessary to kill it. Now what do you think that does for secondary poisoning issues
[00:22:08] The rodent has four times as much poison necessary to kill it. So in that poison is more persistent in its metabolism in its body than a first generation anticoagulant. So now you have a cat.
[00:22:24] You have an owl you have a dog feeding on that dead and dying mouse because remember anticoagulants cause mice to be weak. They may not make it back to the dead in time their nest in time to die there. They may get caught out in the in the open where they’re available to be consumed by by scavengers and carnivores and then they’re fed on it. So now that owl is feeding on that sick mouse he’s like oh I got an easy snack here. Now the owl eats that mouse that has four to five times more toxicant it did what it needs to kill the mouse. And so now the owl takes a dose and then the owl takes another mouse on day three. That was eating the toxicant and then I’m done now you know week on on day seven another mouse is sick and dying and that mouse that owl eats it. So what do you think the cumulative effect of those secondary poisons are having on the owl. Now granted the owl was bigger. It takes more poison to kill bigger animals than smaller animals. The mouse has metabolized some of that toxicant before. Before the owl eats it but the owl is still getting those doses of second generation anticoagulant in its system.
[00:23:58] And the research is showing some scary things about secondary rodenticide poisoning with scavengers and predators that are feeding on rodents. And the research has been enormous on this point
[00:24:17] So I’m being pretty negative here on second generation anticoagulants. Now let me try to dial that back a little bit because some of you may think you should never use secondary generation or secondary second generation anticoagulants and I’m not saying that at all.
[00:24:31] What I’m saying is that you as a past professional need to be prudent and in use products appropriately not just simply go into the atom bomb to solve a problem and that sometimes we get lazy as PCOS.
[00:24:50] We just want we just want to make fast money move on and not thinking about the long term consequences of what we’re of what we’re doing.
[00:25:01] So where should you use second generation anticoagulants. You need to use second generation anticoagulants when you’re in an environment that you can’t control. The amount of available food for the rodents. Let me give you an illustration. If you’re trying to control a rodent population in a situation where there is so much food available your bait is competing with alternative foods that cannot be reduced you will probably need to use second generation anticoagulants because you may only have one chance. To kill that rodent. With first generation anticoagulant rodenticides the rodent has to feed multiple times to get a toxic dose. But if there’s lots of food around why would the rodent come back to your bait. So with second generation anticoagulants. One dose one meal by that rodent is enough to kill it so even if the rodent it goes to your second generation anticoagulant feeds on that rodenticide takes off and begins eating grain or other foods. Maybe you’re have just enough filthy organisation a little place and your client will you know your client will not do anything to remove the available food or the client is simply unable to remove the available food then you’re going to have to use a second generation anticoagulant.
[00:26:44] That’s all you got. Unless you’re gonna be using traps because I don’t want to eliminate other options there because there are other options. But if you’re going to use a rodenticide you’re going to have to probably choose a second generation anticoagulant for that. OK
[00:26:58] So that’s the first generation antiquated identified as well as the second generation anticoagulant for this side so let’s. I didn’t give you the list of second generation anticoagulants and let me give you that.
[00:27:12] Second generation anticoagulant rodenticides include brodifacoum, bromadiolone, difenacoum and difethialone. So let’s go over the first generation anticoagulant rodenticides. warfrin, Chlorophacinone, diphacinone. So you have three first generation anticoagulant rodenticides and you have four second generation anticoagulant rodenticides. So the first generation again warfarin chlorophacinone. diphacinone second generation anticoagulants brodifacoum, bromadiolone, difenacoum and difethialone.
Non Anticoagulant Rodenticides
[00:27:51] All right let’s talk about the non anticoagulants as I said before. non-anticoagulant rodenticide besides kill rodents by means other than anticoagulants by interfering with the coagulation of blood. We have three non anticoagulant rodenticides available the United States go to overseas you can get some other options but in the US we basically have three. Those are bromomethylene, Colecalciferol and zinc phosphate. Now bromomethylene affects the nerve tissue on a particular on the organism so it doesn’t affect the blood of the of the road and it affects their ability to transmit nerve signals. Now one of the interesting things about bromomethylene is that it’s basically designed that once the rodent gets a toxic dose. The rodent doesn’t consume any more bromomethylene. So this is one of the reasons why bromomethylene is available. To the general public as an over-the-counter product that doesn’t need a license to get Colecalciferol is basically vitamin D and it is. It basically affects the organisms it affects the calcium levels in the in the rodent and causes a heart attack in that way. Colecalciferol is the only product allowed for organic farming. Now a lot of people think that if something’s organic it must be safe. That is not true. So if you’re telling your clients all this is organic This is registered for organic use it doesn’t make it safe strict 9 is quote unquote organic right but it doesn’t make it safe right. So we never want to be calling rodenticides. So Colecalciferol is is a non anticoagulant wrote an aside but it is allowed for use in organic areas.
[00:29:58] The last one is zinc phosphide zinc phosphide is used. It’s an acute toxic and it kills very quickly organisms that eat it. If you’re familiar with aluminum phosphide the fumigate zinc phosphide is just the is the bait product. So when the animal eats it and it reaches the gastric juices it liberates phosphate and gas and causes the body to shut down internally that way zinc phosphide. The beauty of zinc phosphide is there is no secondary poisoning risk by any practical means. There’s some theoretical issues not only get too far into the details there but for all practical purposes there’s the zinc phosphide secondary risk secondary poisoning which is pretty small. However it has an extraordinarily high primary toxicity risk so you only need to eat a little bit to kill stuff. It is amazing how toxic it is but in terms of you know if a fox is eating the mice you kill was being falsified the fox will be fine. So that’s one of the reasons why it’s often used in agricultural situations. You may know of zinc phosphate as a tracking powder so the tracking powder usually is at 5 percent and also in the rodent goes through the tracking powder and then begins to groom itself. And that’s how it consumes zinc phosphate and phosphate will persist for four years. That’s why it has to be placed behind walls in areas where people don’t have access to it because it is extraordinarily toxic.
[00:31:35] So those are the two main categories of rodenticides we have the anticoagulant non anticoagulant and then underneath the anticoagulant roadsides we have first generation anticoagulant rodenticides and we have second generation anticoagulants rodenticides and I talked a little bit about LD 50 and then some of the pros and cons of first generation and second generation anticoagulants.
[00:32:01] I hope this helps you choose your parameter stand your products better so that you use them more effectively. Don’t be a robot when you’re doing using rodenticides. Choose your road and the sides wisely according to the situation that you’re involved in they work but try to choose those that are going to be have a less negative environmental impact. While still taking care of the concerns that your client has for needing to control rodents in your particular situation. Hope that helps. Stephen Vantassel wildlife control consultant back to you Frank