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Insect management in grain storage
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Welcome to the University of Manitoba Resources for Agricultural Engineering podcast! Your gateway to discovering the latest innovations, research, and practical solutions in agricultural engineering.
In this episode, host and Agriculture research extension Engineer, Dr. Uduak Edet chats with Dr. Vincent Hervet, a Research Scientist in Stored Product Entomology at Agriculture and Agri-Food Canada, about key aspects of insect management in grain storage, its broader impact on food security and global grain markets, emerging trends, and advice for farmers and grain storage managers on improving their practices.
Hello, and welcome to the University of Manitoba Resources for Agricultural Engineering podcast. I am your host, Uduak Edet, an agricultural research extension engineer in the Department of Biosystem Engineering. This podcast is your gateway to discovering the latest innovation, research and practical solutions in agricultural engineering. Our mission is to forge meaningful connections with agricultural community and help farmers address the engineering needs and aspiration. Today I am joined by Vincent Hervet, who is the research scientist, crop product entomology at Agricultural and AgriFood Canada in Manitoba. Before we discuss insect management in grain storage, please tell us about yourself and what inspired you to study insects.
Vincent HervetHello, Uduak. Thank you. Yes , that's a very good question. So, I grew up in France in the middle of the country on ta farm, and where I grew up, there was a lot of insects around when I was a little kid. I never paid them too much attention, to be honest, until one day when I was six years old, I found this beautiful butterfly. It was the old world swallow tail , big yellow butterfly, which landed on a rose in front of the house where I grew up. And I caught it with my hand . It was so big I could hardly handle it. Then I called my mom to put it in a jar, which I did, and then I fed it flowers for several days and observed it and eventually died. And I didn't want to part with it because it was so beautiful. So then my mom told me, some people pin insects, you know, and keep them, and you can do that. So I did that, and then I was looking for more butterflies, catching them, always trying to keep them alive as long as possible. And then I extended to other insects, always observing them, feeding them as much as I could, learning as much as I could, buying all sorts of entomology books. So my early exposure to entomology was just personal interest. And eventually , because I was very interested in entomology, that's when I pursued a master's and PhD in the field of entomology. So I studied , physiology of crop pests primarily, and other aspects of crop pest control, integrated pest management. And that was conducted here in West Bridge , Alberta with the research centre over there, Agriculture and Agri Food Canada, and with the University of West Bridge. And when it was time to look for a job, I applied to one in grain protection and entomology of stored grain, another stored products or stored product in stored food. And so I got the job. So that's what got me into this initially, personal interest, and then , need for a job. And it's great to be able to match both.
Uduak EdetOkay . Thank you. Good to know that you've virtually , used your childhood , this in transfer to build as a career . That's good to hear. I'm just wondering , what is insights monitoring insects monitoring installed grains such an important topic?
Vincent HervetYeah, so insects installed grain bin are very tiny. So they're so tiny, they will actually be able to travel between the grain kernels , most species and fairly fast. And so they're so tiny and they're so insidious and they develop very fast, and they can very quickly destroy the grain without you knowing it because they're so tiny, you can't really see it. For example, the most important pest of stored grain in Canada is the Rusty Grain Bettle. It has an average of two millimetres long. It's a tiny little brown bettle, and it has the habit of degerming seeds. So it goes from one seed, basically they will germinate, and then it'll degermenate a whole bunch of seeds, and you don't see it because the seeds, the seeds have a pinhole. So what might look like good seeds, in fact, dead seeds. So the problem with this particular beetle, so the Rusty Grain Beetle is 95% of the insect detections in Canada, in elevators in Canada. So I will primarily talk about these species because it's by far the main pest of stored grain . So the problem with it is once it degerms a seed, so all the seed producers will have seeds that don't germinate. Actually, I've talked to some of them. And in fact, seed farmers tend to hold seeds in their grain bins longer than other farmer. And that is a huge problem with the Rusty Grain Beetle, because the Rusty Grain Beetle will over time be able to develop into such numbers that it'll damage a whole bunch of seeds. So those seeds won't germinate once they're planted. But even the seeds that are kept for human or animal consumption, when it's degermed, then there it starts to decay basically. Then it starts to, some natural processes occurring , the seed that degrades its internal quality. So free fatty acids are produced and it gets rancid more quickly. So that's why we don't want the seed to die too early or before we process it, so we don't see them. So that's why it's important to, to know that the insects are there and to do something about that, to prevent them from proliferating in the grain bins.
Uduak EdetOkay. So how does this affect food security and global green markets?
Vincent HervetYeah, so in Canada, because we enjoy a lot of cold weather, particularly here on the prairies, it's not as bad as in other countries, but globally, about one third of the grain produced is destroyed during storage. I mean, the estimates vary widely. And the reason is because we don't really know what the losses are in farms. It's very difficult to know that. So I've seen a huge range of estimates. I think one third is pretty conservative. Globally, that's what we're looking at, huge losses on farm. And not just on farm, but primarily on farms. So that's why it's so important to be able to manage those insects and not just insects, the mold as well. To make sure the grain is kept under ideal conditions. Otherwise, it's a huge loss.
Uduak EdetOkay. When you talk about grain insect infestation, does it affect all grain or there specific type of grain that insects tend to focus more on?
Vincent HervetYeah, that's a very good question. And indeed , not all grains are affected the same. Cereals are by far the most impacted by insects during storage. So I conducted a study where I put traps in various grain bins and looked for insects. So what I found, is in Canada we are virtually not affected by insects during storage. I say in Canada, because if you go to tropical countries, you have the so-called brukeeds, or the bean weevils, which are very important. They damage pulses a lot. But in Canada it's extremely rare. We do have the bean weevil it's extremely rare overall, not a problem. If you have pulses in grain bins, you're pretty guaranteed you won't have any insect. Everything that is oil seed as well. Extremely rare to have insect problems in oil seeds. What I found from personal observations is many insects will feed on the oil seed, but it'll take them a very, very, very long time to develop and multiply such, so that during the storage time, which is usually less than a year in Canada, it's just not a meaningful impact, you know, so the real problem in Canada is really cereal. So that's where we find the largest diversity of insects and also they develop the fastest. So that's where we really need to keep an eye.
Uduak EdetOkay. So with this insects infestation, what are the traditional methods actually used to, to monitor insects in grain storage?
Vincent HervetSo the traditional method is to not monitor, unfortunately. The problem is , it's very time consuming. You know, farmers and other people, they have so many other things to do, you know, it's one more thing. And I mean, understandably so, you will have to actually climb into the grain bin, put the, the trap in it. The trap is a tube with holes all around, and a little insect reservoir at the bottom. So you push it into the grain, then you wait a certain amount of time, you know, 2 weeks, 1 month, and you retrieve the trap. You look what insects are in there, and you kind of have an idea whether you have an infestation or not. You look if there's many insects or not many insects. So you do have , there's also the safety aspect. You do have to climb up the grain bin and climb down with the trap. So that's a problem. So I mean... those traps are available. Another problem is it's not super cheap. If you were to put some in all the beans , there will be a lot of time spent and it'll be a little bit expensive. So that's why people typically don't do it. It's pretty rare. But otherwise those so-called prop traps are the way to monitor insects in grain bins. So there is also an electronic trap that exists . It's called insector. It has a little laser at the bottom that detects the insects that fall into the trap. And there is a software that analyzes this , so you don't have to go into the grain bean but this system is very expensive. So yeah, those are the main problems why people don't monitor grain in grain bins.
Uduak EdetOkay. So, are these method effective or is there any other technology that you think might actually monitor or detect insects better than the ones you've mentioned?
Vincent HervetYeah, so it is effective in a way, although we don't have any baseline numbers. So if you see a few insects, is it a big problem? It's not a big problem. It's very subjective. And some studies have tried to assess what number is significant. But there are so many different parameters at play that there's no... it's not conclusive. So basically right now, so that's one of the problems we don't really know. So it's not super effective for that. If you see a whole bunch of insects in the trap , then you know you got problem. And if you see virtually none , you know, you don't get problem. Other than that , in the future if there were electronic system, that were cheaper than the ones currently in the market, I just talked about, that will be a lot more efficient. So we're not there yet. So I believe that progress needs to be made to improve the efficiency for monitoring insect in grain bin , and I think it'll come.
Uduak EdetOkay. You mentioned one thing, which is about putting the probe inside the grain bin itself. Is there a specific location that farmers should focus on when, when placing those probes?
Vincent HervetYeah, very good question. Once again, once again... sorry. So the best location is at the very tippy top of the inverted cone at the top of the grain mass . So there, I guess there's 2 reasons for that. One is many insects tend to climb. If you put something high, they will tend to go up there. So you do find more insects for this reason. Another reason is it tends to be moister and warmer here at the top of the cone. And when you aerate the grain to try to dry it or cool it down, it starts at the bottom. And the last bit of the grain that dries or cools down is the top of the cone, the very tippy top of the grain mass . And so the insects like it when it's warm and moist, and so they tend to be there. So if you want, and usually , a hotspot tends to develop there as well. So that's why it's important to monitor there. So if you can put a trap anywhere in the grain bin, the top of the cone is always the best place to spot the insects.
Uduak EdetOkay. Are there any regulation or industry standard for actually monitoring insects in storage bins?
Vincent HervetThere is no regulation or industry standards for monitoring insects. However, the Canada Grain Act stipulates that it is forbidden to sell or buy grain that processes at least one live grain pest in it. So when a farmer goes to the elevator to sell the grain , they take a sample and if there is at least one live grain pest in there , they are not allowed to accept this grain. So there is no regulation for monitoring the insects, but there is regulation for not having any live insect in the grain .
Uduak EdetOkay. Now, you know , there's this buzzword about AI and artificial intelligence machine learning. Do you think it has any rule to play in terms of insects monitoring and grain storage?
Vincent HervetYeah, I think so. Like, if we could more efficiently detect insect infestations, then we would know when it's time to do something, because the more you wait , the worse the problem, and then the harder it is to control the problem, and also the more expensive it is . And artificial intelligence or machine learning could very well be one of these ways to help. Could be at the farm , could be at the grain elevator, in the grain they receive , could be in the grain mass. Yes , most definitely. And it is something that researchers are looking into right now. So hopefully in a few years we'll see something about that.
Uduak EdetOkay. Thank you. What's the role that temperature, humidity and even the bin size... what role do they play in terms of the insect activity within the grain bin itself?
Vincent HervetOkay. So we know that the higher the humidity and the higher the temperature , the faster both mold and insect proliferate in grain. Actually, there are a number of graphs for safe storage guidelines on the Canadian Grain Commission website. These are for insects... sorry for grain spoilage. So what is the safe zone in term of temperature and moisture content to prevent spoilage during storage? These work very well with mold, but I'd say they also work very well with insects. If you can keep the grain within those safe storage guidelines, the grain should be free of both mold and insects. The only difference with insect is nearly all species of grain insects will stop multiplying and developing below 18 degrees Celsius. A few of them will still develop and multiply down to 15 degrees Celsius. So if you can bring the grain down to below 18 degrees Celsius, you will basically stop any insect infestation. So that's why it's important to decrease grain temperature as early as possible. And then it'll be safe from insects below those temperatures. Oh, the size of the grain bin. Okay. I did a study, again, a survey across the prairie provinces of Canada to look at insects in grain bins. And I did notice a trend related to bin size. Almost inevitably the larger grain bins had less insect problems, but they also had better grain quality in terms of moisture content and temperature. So bigger grain bins resulted with less insect problem. But I think this is because those bigger grain bins tended to be more modern, often equipped with temperature cables and were better managed. I think that's why I don't think it's the size of the grain bin per se, that made a difference. I think the difference is the way people manage bigger grain bins as opposed to older , smaller grain bins, which may have a wood floor or which may not be rated . So that's where the difference is .
Uduak EdetSo what kind of, like, the biggest challenge in detecting or controlling insect population in grain storage?
Vincent HervetI think the biggest problem is farmers are just too busy to... I mean, deploy traps, monitor traps. And as I mentioned, the traps are the most efficient when you put them at the very tippy top of the grain masses . So you actually have to climb all the way to the top of the grain , means very challenging. It's not easy. So I think that is the biggest challenge when it comes to monitoring insect populations. So again , if there was some kind of electronic measures, you know, there were no insects, that will solve this problem.
Uduak EdetOh , okay. You know , we look at Winnipeg actually with this last... with this current winter, you notice the way the temperature fluctuations. Like it goes very low and it goes high, and people are talking about climate change. Do you think there's any, as in, have you observed any shift in terms of the insect behavior with this recent change in terms of the weather?
Vincent HervetOkay, so it's hard to know because there hasn't been a survey before the one I did across the prairies , or across Canada for that matter, looking at insects in grain bins. So if we don't have a baseline, it's hard to know what you see , if it's normal or not. I think it is normal what I saw, because only insects that were well known. And the more the insects that were the most known, like the Rustic Grain Beatles were the ones I found the most primarily. So I don't think that we see an impact of climate change. I did not collect any new species, actually, that was part of the rationale why I did this work was , you know, maybe this new species moving into Canada from the south, but I did not find any so far . So it's maybe early days. There definitely are species in the United States that definitely don't like coal too much, and if global temperatures were to increase by a couple degrees , we most likely find them here. So it's probably a matter of time, and we are not there yet, I would say .
Uduak EdetOkay. You talked about conducting a survey, conducting a research. Can you kind of give an overview of what, what the research is all about?
Vincent HervetResearch in grain storage?
Uduak EdetYes.
Vincent HervetOkay. So I work on 3 different things mainly. So the detection of insects, the prevention of insects in stored grain and the control, if you can do anything . So I guess the survey that I conducted, you know, putting traps in grain , this goes into detection. So that's one project that I'm currently working on. I'm also doing some work on the use of temperatures to control insects. So all grain insects will develop the best between 20 and 35 degrees Celsius above or below this temperature. They will stop not developing as fast and further above or below, they will start to die. So , I've looked at how we can use cold temperature to control insects in grain. Particularly the bin. We... because there was some trade implications with the bin, with some countries that buy a lot of Canadian bins , had quarantined on that bin weevil, and that was a problem. So right now, and I have a third project also right now, which is how we can use beneficial insects like perisoids to control growing pests in facilities. So those insects will go and target the pest and kill them. So you don't have to do anything that... it's just natural control.
Uduak EdetOkay. So based on the research you've done so far, what advice can you give to farmers?
Vincent HervetOkay. So primarily from mysurvey of insects in grain bins across the prairie provinces, also I did measure grain moisture content , temperature, and also when the grain was harvested and where the fans run to aerate the grain and these kind of questions. And one thing I noticed , one of many things I noticed... one thing was the fall when the temperature, the years that have higher temperature during the fall, we see more problems. The grain quality is lower, there's more insect problems , there's more mold feeders. So I found a lot of mold feeders, which only feed on mold, not on grain, and some bins have a very high number of those. So that tells you that grain quality is not optimal because that means there's mold or there has been mold that started to develop. So yeah, fall temperature is one thing. Another thing I noticed is people don't always aerate the grain right away. They wait for the temperature to cool down , to cool down the grain. But there are 2 things we can act upon, there is temperature, but there is also the moisture content and you can regulate any of these . So after harvest, if the temperatures are still too high to cool down the grain, one thing that can be done is dried . And one thing is the higher the temperature, the faster the grain will dry. It's... you know, because the molecules move faster, so then they dry faster. So immediately after harvest, I will recommend to turn on the fan to try to dry the grain. If you wait too long, if the fall temperatures are too high, the grain is going to start to spoil. Another thing is , during the night or early morning, after time , the temperatures are low enough at the end of the summer or early fall to cool down the grain. So we don't have to wait for the, I would say , temperature to be very low to start cooling down the grain. The earlier the better . Consistently I found that the people who waited too long, usually the grain quality had already gone down. And usually the insects were already in high number, and usually there were a lot of mold feeders. So yeah, turn on the fan, the earlier the better to dry the grain, to cool down the grain. Another thing I noticed is people don't seem to really know how to handle the grain during the summer if the grain is, so most of the grain is sold during the winter month , and that's good because it's cold and nothing really happens. But if the grain is kept during the summer , the problem is it can warm up. And then you have problems of mold and insects, and you don't have cold temperature to stop all of that. So what do you do? So, again, based from observations of what different people do , it seems that if the grain is really cold during the winter, you know, turn on the fan during the winter, you cool it down , below zero degree Celsius, like minus 10 or something. This grain will remain below zero degree Celsius the whole summer because it has such high insulating property. Grain is very good at insulating, right? So if you don't touch it , it'll remain cold. And at these temperatures, insects will not be able to develop and mold will not be able to develop either. 4 degrees Celsius is the limit at which many molds can no longer develop. So it's good to keep the grain below 4 Celsius. So , I will recommend, however, to monitor the moisture content at the top of the grain mass , because if you have a whole bunch of cold grain and it's hot outside and moist, there is a risk that the top of the grain mass might suffer from condensation. I did not notice that. Interestingly, I did not notice that the people who kept the corn growing throughout the summer came fall it was still good, and there was no excess moisture at the top. So that's very interesting observation. But regardless, I will still advise farmers to monitor in case there is excess moisture recognition at the top. And if that's the case would recommend moving the grain into another grain bin, turning it over to another grain bin to homogenize the moisture content and temperature gradients. So that would be my main advice.
Uduak EdetOkay, what role does engineering or agriculture engineers can actually assist you in helping you manage insects in stored grain?
Vincent HervetOne thing... so yeah, I work at the University of Manitoba , so I collaborate with engineers here in the Department of Biosystems Engineering. So one thing that we can help each other on, is to develop those so-called sensors, actually. I work with Dr . Fujian and so he has a project to develop sensors to detect insects in grain. So there's different ways we can detect insects in grain. Some people have used sounds or vibration created by insects feeding on the grain. Other people have looked at the increase of CO2. Or there is a number of other things we can look at. Actually, I don't want to say too much about this particular project, because I don't know how sensitive it is , and since I'm not the main PI on it's Dr. Fujian. But I would just say that he's working on the development of sensors that if it works, it could potentially revolutionize the way that insects are monitored in grain bins. Another thing is to look at is population dynamics. Many engineers are also modelers , so they can develop models. So if we look at certain conditions of grain, you know , temperature, type of grain , moisture content and so on. And the insects that are out there, then you would know how long it'll take for a certain species to multiply in the grain. And where you know whether your grain is safe or not, or if you need to do something. Or anything that's related to grain management. Are there things that my predecessors have found , if you use an auger or a grain vac for this instance, you can kill the vast majority of insects in grain. Nearly a hundred percent. In fact , especially in the case of growing back, yeah. Because of the insects are fairly squishy if you think of it, and fairly fragile. So it was found that the augers will kill nearly all insects that are outside the grain, you know, by being carried through the auger, they just get crushed. Remain the insect inside the grain and it was found that grain vac, especially if there is a 90 degree angle in the pipe and you don't suck up too much grain at once, that these, this will impact onto that angle and that will kill virtually a hundred percent of all the insects, whether they are inside, outside the grain, but the grain has to be fairly dry. I have to mention it was from... if the grain is not sufficiently dry it doesn't work too well . So think like this, you know.
Uduak EdetOkay, for listeners interested in the technical side of the work you've done , could you explain some of the data analysis or modeling technique that you use in, in your research?
Vincent HervetYeah. I can mention one interesting analysis is the probate analysis. So this is an analysis we use to confidently extrapolate a set of data, for example. So when I work with temperature, so we look at how long it takes for an insect to die at a specific temperature, and we can look at multiple temperatures, but we can't look at every single temperature, you know, that will take too long. And so if we have a few different temperature and we know the rate of death for each temperature we can analyze with the probate analysis. And it does a very good job at extrapolating to give a good confidence interval of how long it'll take the insects to die at different temperatures, those you haven't tested. It can also be used to see how long it'll take an insect to die at a certain temperature. Like the bin Weevil at -5 degrees Celsius is a temperature we use. So we looked at the LT50. So that's the lethal time where you get 50% of mortality and then LT95. But to get the LT100 is very difficult. You have to do this experiment a very long time, and usually you don't have enough insects to get the numbers, you need to get that 0.0 0 0 0 0 1, you need a lot of insects. So we use the probate analysis to extrapolate those data to see where we get the 100% control at certain temperature, for example. So probate analysis is a very interesting analysis and is very useful.
Uduak EdetOkay. That's good to know. Looking ahead, what emerging trend or research area in insights most monitoring are you most excited about?
Vincent HervetYeah, to me it's all the AI. At first I wasn't too convinced because of the cost involved. Because if we were to develop, you know, a sensor that can detect only insects, but then you look at the cost , like in our case prohibitive, It's not gonna work, nobody's gonna buy it. However, we've seen with the modern technology, like for example, the sequencing of molecular sequencing of DNA , like it started just a few , like 20 years ago was 10 of thousands of dollars to do some kind of sequencing. Now it's like 0.0, you know, $1 for one sample. So the cost has gone dramatically down, and it seems to be the case with many of these new technologies. So I think this is... I think is what is exciting. We can develop sensors, you know, right now the cost will be too prohibitive, but if the technology is there and after a certain number of years , once the technology what it's make what it's easier to produce it there should be a price decrease that make it possible for farmers to buy. And then they would know in real time what the insect situation is in their grain bin .
Uduak EdetOkay, is this where you see the future of insects monitoring going in the next five or 10 years, or it is gonna go a different direction from AI?
Vincent HervetI think, you know, the traps I previously mentioned, the prop trap where you have to climb the grain bin, putting it in there, those have existed for a long time and people don't use them. It's simple, but it's just too much work. So I don't think that's the future. I think the future is something like the sensors that are on cables in grain bins, so right now we have temperature sensors primarily. You can also have moisture sensors and sometime you even have CO2 sensor and in fact , a rise in CO2 is the very first indication that you have organisms developing in your grain . Could be mold, could be insect. So I think this is the future, whether it's CO2 sensor or other sensors , I do think that's where I see the future going. Like something incorporated with those cables , with those sensors to detect more things such as insects.
Uduak EdetOkay. So on the general notes, what resources would you recommend for farmers or storage managers looking to improve their insect management practice?
Vincent HervetThe main thing I would recommend, and the first thing I always recommend is those safe storage guideline graphs on the Canadian Grain Commission. And it's , so it shows very clearly which temperature and which moisture content the grain will spoil or not spoil. That's very useful. But on this website, there are many other things. It's not just that if you look at managing grain, you will see how to prevent insect infestation or spoilage, how to disinfect grain bins. This is available. It's already there. It's on the website. So that's the main thing that I would advise people to check if they want to improve grain management. There's many other things I could mention, but I think it'll take too long. And I think it's too detailed. While this I think is big picture, it's readily available, it's very useful. So I will direct people to this website.
Uduak EdetOkay. Thank you. Is there anything else you would like to share about insect management in green storage?
Vincent HervetWe've already talked about various aspects of it. Keep the grain cool and dry and then you won't have any problem. Oh yeah. One thing I should mention is it's impossible to prevent insects from entering the grain bin. The insects are so tiny and the grain bins are not hermetic, which means you cannot stop them from entering. They will enter, I guarantee you, if you were to check every grain bin in much detail, you will find insects in every single one. The goal is not to stop them from entering. The goal is stop them from multiplying. And you do this by keeping the grain temperature and moisture content low.
Uduak EdetOkay. Thank you so much Mr. Vincent. It's been a pleasure meeting you and learning more about your experience with insect management in grain storage. We're certainly looking forward to hearing more about your research and experience. Thank you all for listening. Please stay tuned for more upcoming podcasts on the University of Manitoba's Resources for Agriculture Engineering, your gateway to discovering the latest innovation research and practical solutions in agricultural engineering.