Beneficial insects

Thank you. Thanks so much. It is always an absolute pleasure to be online here with Local Land Services. I really enjoy these presentations and I really love the kind of engagement we get from the audience too. It’s absolutely wonderful.

Along that note, for everybody who has just joined us, we’ve asked everyone at the very beginning to write their name, their postcode, and their favorite beneficial invertebrate into the chat there so we can see where everyone’s coming from.

Now, as Le said, today we’re going to be talking about insects and invertebrates—the ecosystem services. There’s actually a huge amount of benefits of having insects, and we’re talking just about a very small piece of that pie today: how to identify different natural enemies in cropping systems specifically, but also this applies across many other systems. These would be beneficials across many different cropping and garden systems. And we’re going to get some new information on the toxicity of different pesticide groups to beneficial insects, and that’s the section that Rob is giving at the end.

So, we’re talking about ecosystem services. I mean, this is a very human-centric approach. It’s basically looking at the advantages we get for having nature around us, and insects provide a huge number of benefits to humans. I think a lot of the general public don’t realize just how important insects are to the functioning of our ecosystems. Especially what we’re talking about today is going to be pest control.

At the top here, most people would recognize pollination as being really important—a really important ecosystem service. Everybody knows that bees are needed for pollination. Also, insects and bees are a really important source of food for not just birds but reptiles and mammals as well in our ecosystems. There’s this idea that if we got rid of all the insects, there’d be nothing for a lot of other animals to eat. And also decomposition—so a lot of people talk about soil health but don’t really know what it comes down to. Often it’s down to these microorganisms and these insects in the soil, and that’s really, really important for creating healthy soils.

This little one at the top here is seed dispersal, which is basically that there are particular ants that these native plants need in order to take these seeds and bury them somewhere else—which is a completely different lecture altogether. But today we’re talking about pest control. So, we’re talking about predators to start off with, and we’ve got a list of predators here: ladybirds, beetles, hoverflies, lacewings, predatory mites, and spiders. I’m going to go over today some details about how we can identify these different groups because it’s not always easy.

We’re also going to play a little game—we’re going to play Pest or Pal in the Zoom polls. I’m going to show you a picture of an invertebrate, and you have to guess if it’s a pest or pal. Pal would be a beneficial insect. Then you have to vote in the Zoom poll. So, let’s give it a go with this one. I’m going to launch the first poll, and I want everybody to take a guess as to whether this is pest or pal.

Got some good answers coming in. Oh, it’s pretty split. We’ve had lots of people vote now. For anybody who wrote pest, can you write the justification for it in the chat for me please? I’d love to see what comes through. This may be a slight trick question. I love everyone that’s put pal because you know ladybirds are beneficial insects. 60% of people have said pal and 40% of people have said pest, which means that some people are on to my little trick. There we go—this one’s a pest. It was definitely a trick question because this is a 28-spotted ladybird, and there are a couple of people in the chat that already know this, which is fantastic. Basically, lots of spots means it’s a pest. Most ladybirds are predators—we’ll talk a little bit about them—but these ones can feed on quite a lot of different crops, so we keep an eye out for them.

So, lady beetles—I love these as a beneficial insect because they are predators both as larvae and as adults. You might notice these tiny little yellow eggs—you might have recognized them being somewhere. And these really, really interesting-looking larvae—lots of people kind of recognize them but don’t realize that this is what a baby ladybird looks like. They’re really spiky, often black and yellow, and they’ve got these quite big jaws at the front there, which is a really good indicator that they’re predators. Then they pupate into a little ball like this and then come out as a gorgeous ladybird. You may just notice one or two different species, but there are actually over 6,000 species of ladybird in the world and over 500 species in Australia. We do have these common spotted ladybirds—they’re really good predators, especially of things like aphids. We’ve also got mealybug ladybirds that specialize in eating mealybugs, even fungus ladybirds. And there’s this picture here now of the 28-spotted ladybird, which is one of the very few species that is actually a herbivore and a pest.

So, here’s our next one. Let me launch the next poll. That was the result of the last one—now we’re going to launch this one. Okay, who wants to tell me whether this is a pest or pal? I’ll give you a hint—it’s a beetle. Not a very good hint though because beetles are one of the most diverse groups of insects out there. A little bit of a split. I’ll give you one more second and then I’m going to share the results and see what we come up with. Share these results with you—so 22% think it’s a pest and 78% think it’s a pal. This one is a pal. So, this is a carabid beetle. They’re quite big—usually you can find them in the soil. They’re kind of ground-dwelling beetles, and they can either reduce weeds—they can eat weeds—but they also eat pests because they’re quite good predators. They’re very variable, but they do again have these forward-facing mouthparts. If you ever see these big chompers, it’s a good indication that this is going to be a predator. Also, the long strong legs—so if we have a look at this guy, it gives us an idea. They talk about this hot water bottle body shape, and that’s quite unique.

Among the beetles, there are so many different species of beetles—2,500 just in Australia—so you’re never going to be able to identify even a tiny selection of them, and they’re very, very diverse. But if we’re trying to work out what a carabid beetle looks like, they often have these long kind of stripes on the back part of their body and these big strong legs and bulgy eyes.

As larvae, it’s a little bit more difficult because again, super variable. These two are both carabid beetles, but you can tell they look quite different. They tend to have these longer kind of processes at the end of their body and again, look at these jaws—even as larvae they’ve got those big noticeable jaws. So don’t just assume that any kind of little wriggly thing that’s in your soil is going to be a pest chomping on the roots. These guys are actually the good guys.

Here’s another one—this is also a beetle. I’ll launch my poll. What do we reckon with this one—pest or pal? This might not be one that you’ve encountered before, but I’ve given you a few hints already as to how we might be able to identify what kind of things it feeds on, whether it’s a predator or not. I’m getting pretty good response here as well. I love that everyone’s voting by the way—thank you. It’s really, really lovely to see all these votes come through. It means I know you’re listening. Yeah, excellent.

Okay, I’m going to be just super quick with these ones. I’m going to end that one and share it with you. Most people are on the money with this one—this is a vegetable beetle. You may have heard of wireworms or false wireworms before that can attack cereals.

Moving on from the beetles, let’s talk about Rob’s favorite—the hoverflies. These are absolutely fascinating little insects, often mistaken for bees because they’ve actually evolved that way. They’ve evolved to look like a bee because generally you don’t want to eat a bee—you know that you’ll get stung if you come along and eat a bee. These guys don’t have any stingers—they’re flies, not bees. You can see they’ve only got one pair of wings, but they’ve worked out that if you look a lot like a bee then you’re much less likely to get eaten. That’s why they look that way.

So they’ve got these tiny little antennae at the front, big fly-like eyes—which is a good way to identify them as well—and a really flat body if you see them from the side. The hoverfly really does what it says on the name too—sometimes you go out into the garden or the field and you’ll see them just hovering around. It’s a really beautiful look. And again, one set of wings, so we know that it’s a fly and not a bee.

But as larvae, they look quite like a fly larva you would expect—they’re quite maggoty and pretty nondescript. This one here is hanging out with a whole lot of aphids because it’s eating them, which is another good thing. This is another one of those ones that is a really, really good predator when it’s in its larval stages. So they’re kind of a greeny-brown color, but the most defining feature is this kind of white stripe that often goes down the back, and they’ve got these hook-like mouthparts which they actually grab and pull in the aphids with. It’s quite fascinating to see if you can ever keep an eye on it.

Here’s a different little critter for you. I’ll launch my next poll—what do we reckon with this one, pest or pal? You might recognize this one from your own gardens. They’re pretty ferocious-looking beasts, and they seem to have something on their backs—something a bit weird going on there. This is taking people a little bit longer to come through with their results. I’ll let you have another half a minute to have a think about it.

I will say, I actually found one of these in my house the other day, which was very strange—not what you would have expected. They don’t usually live inside, but a pleasant surprise nonetheless. Okay, 32% say pest, 68% say pal. This one’s a pal. So again, this is the larval stage, and this is a beautiful lacewing larva. They are amazing predators—very, very good at controlling aphids. Some of them put this weird debris on their back—sometimes they even collect the carcasses of the food they’ve already eaten, put it on their back, and carry it around as camouflage. If you ever see one, they really do look just like a little scrap of something that’s crawling along.

So let’s talk a little bit more about lacewings. Again, there are quite a few different species you’re looking at. The most common ones are the brown lacewing and the green lacewing that we would see in Australia. You probably recognize their eggs but might not have known what they were. They lay their eggs on a long stalk with the egg on the end, often in kind of a horseshoe shape as well, often up underneath balconies and things. I’ve got loads at my house at the moment, and they hatch out into those tiny little grubs with the big nippers.

The way you distinguish an adult lacewing—they’ve got these really big eyes, clear folded wings (hence the name), and very long antennae. They’re kind of different from a dragonfly in that they fold these wings right back over their body. These are the larvae, so again they look a little bit different between the two species. The green lacewing is the one that carries debris on its back, but they do have these really big sickle-shaped jaws at the front and a tapering body at the back.

Now, people generally think of mites as being a bad thing, but there are actually lots of species of predatory mites which can be really good predators, and we definitely want to encourage them—especially in cropping systems. So the Phytoseiidae, the Anystidae, and the Macrocheles are all really good positive mites that we want to have in systems. Mites are always going to be very, very hard to identify. These do look quite different from the main pest such as the red-legged earth mite in that they usually have a big black body, and these ones are quite red. But I’m not going to expect any of you to be able to go out into a field and instantly identify a mite unless you’ve got a really good microscope.

I can tell you they do have slightly different behavior. These ones here—the whirligig mite—they move around in little circles. They’re usually not clumped in groups like a pest mite would be. And these ones are easy—these are the snout mites. They’ve got a big point. When I say easy, these guys are still teeny-tiny, so you’ve got to be able to get a good look at them. But we know that they’re a mite because they’ve got that one big body part rather than multiple segments like an insect.

Got another pest or pal now. This one is a bit harder. Let me get my poll up. It might be hard at first even to work out what kind of insect we’re looking at here. I can tell you that it is a beetle larva, but do we know whether it’s a pest or pal? Still got lots of votes coming through, which is absolutely wonderful—70% of people put their votes through. It’s looking pretty good. Okay, going to end that one, and this one is a pest. So we’re looking at these false wireworms again. This is the eastern false wireworm, and you’ll see that the mouthparts are quite different to those carabid beetles and the predatory beetles. They’ve got small downward-pointing mouthparts, and that’s an indicator that it’s going to be a pest because it might be chewing on things like roots and foliage. So again, it’s really hard to actually work out what species you’ve got unless you’re a beetle expert, but if you can have a look at some of these general features, that can be a little bit helpful.

Now, I just had to put this one in here because my background is in spider biology, and I’m very, very passionate about them and all the benefits that they bring. Spiders are another one of those super diverse groups in that there are over 40,000 species worldwide. We’ve got over 3,500 species that we know about in Australia, but there are lots more that haven’t had nearly enough work done on them yet. The great thing about spiders as predators is they’re generalists, so they eat all sorts of stuff. If you have a diverse group of spiders, then they’re able to control a diverse community of pests.

You’ve got some that are foliage dwellers that jump around like jumping spiders and lynx spiders, ground dwellers like the wolf spiders, huntsman which will generally be on the bark of trees, crab spiders which camouflage themselves in flowers and then sit there waiting for pollinators to come in. So, you know, generalist means that they don’t always get the bad guys—sometimes they get the good guys too. And the orb-weaving spiders, which are of course really good for catching moths and flies. I could literally give a whole other hour talk on spiders, so I will move on because otherwise I’ll get stuck. I think this is our last pest or pal.

I’ll share that last poll. Next one coming up—give me an idea what you think for this one. The larval stages are always going to be really hard, and I mean, it’s one thing to see a grub that’s up on—oh, I’ll just get everyone to go on mute. There we go, thank you. But it’s another thing entirely to actually be looking at these critters out in the soil.

Got most people answered, a couple more coming through. I’ll end that one now. This one’s a bit more split—33% say pest, 67% say pal. This one is a pal. So we have a close look at it—these big pointy jaws at the front here—and this is the larva of the carabid beetles. Carabids are really quite common, that’s the reason I’ve got them up twice, and it’s something that we always get loads and loads of questions about. So I like to kind of introduce these to people as actually really beneficial things to have in their gardens. Sometimes people take a broader approach to pest control and they see all these beetles crawling around in the soil and think that it might not be a good thing, but that’s not always the case. So again, we can see these nice forward-facing mouthparts.

Now I get to talk about an equally fascinating subject, which is parasitoids. We were talking about beetles being diverse, but there’s actually the theory out there that parasitoids are even more diverse. Basically, for every species of insect out there, you’ve probably got a couple of parasitoids to go along with it. The current thinking is that there’s probably over 500,000 species of parasitoid, but to be honest, we just really don’t know. There was even a news story that came out yesterday that said what we thought was one species is actually 16 different species of wasp.

So again, I’m not going to ask you to identify these individually—you’re never going to be able to work out what actual species we’ve got of these wasps. I wouldn’t be able to either. But we can think about generally the kind of jobs that they’re doing, what kind of pests they might be attacking, and how we can encourage them. The other thing is that they can be teeny-teeny tiny—like 1 millimeter kind of tiny. But the way that we can tell a parasitoid wasp from a larger kind of stingy social wasp is they’ve got this very, very long ovipositor at the back, and the name says what it does—“ovi” = egg. This is how they lay their eggs. So this is how they either inject their eggs into their host, which I’ll talk about in a sec, or lay their eggs on top of the host.

People see that sometimes and they’re petrified because they think it’s a stinger, but these wasps will never sting you. They don’t have a sting—they have no capacity to sting. But they will lay their eggs in caterpillars. And this is the size comparison for European wasp—so this is like the biggest possible parasitoid wasp, and this is the smallest. They are very, very small.

Now, within this group of wasps, we have both generalists and specialist species. So there are some parasitoid wasps that will only lay their eggs in one particular type of pest. But across the diversity of parasitoid wasps that we know of, they can control a huge range of pests. Very, very common for controlling caterpillars, also for pest beetles, aphids, true bugs—and basically, if there’s a pest, then you can look for a parasitoid to control it. That’s some of the really interesting work that we do at Cesar. You basically go out, collect a whole lot of stuff—a whole lot of a pest species—so if you’re interested in armyworm, collect a whole lot of armyworm, bring them back into the lab, and see what pops out. It’s really fascinating research.

And we can encourage these species either by good practice or by releasing them. There are companies which actually breed these parasitoid wasps and you can release them en masse, which is called augmented biological control. But also there are lots of ways that you can encourage them just by good practice on a farm.

So to talk about the different types of parasitoid wasps that exist—they have very varied lifestyles and life cycles. If you have a look at this picture here, this is a moth life cycle, and we actually have parasitoid wasps that will attack every different stage of that life cycle. Sometimes it’s just within a single host, and sometimes they will lay their eggs on lots of different hosts. Sometimes they attack one stage, like an egg, but they don’t actually emerge until they pupate.

To give an example of some of these—this is Trichogramma. They are an egg parasitoid. You can see them laying the egg on the fruit fly.

Here we have another one—this is Microctis and a quite gross video of the larva which is hatching out of the caterpillar here. Then we have the ones that will lay multiple eggs on the outside of the caterpillar—and again, quite fascinating and gruesome, this idea of that coming out. I’m going to skip through because it slows down my video a bit. We also have species that will attack the pupal stage and then emerge later.

Now, these species are very, very small, so it can be hard to know whether you’ve got any of these good bugs in your garden or in your fields and whether they’re doing a good job or not. But there are signs that you can look out for. Often, if you’re looking at caterpillars, this one at the top is choc-a-block full of eggs. Also, if you’re finding dead caterpillars in the fields, you can often look for the exit wounds of where the larva has come out. So just inspecting the dead ones that are around in the field can give you an idea. This one down here is a carcass surrounded by the pupae that have come out. They emerge from the body of the caterpillar and then spin this little nest and sit in that until they hatch out. That’s a really good sign to look out for too.

Now, aphids are another pest group which is really highly parasitized. You can see with this picture here—the little green ones are the normal aphids, the browner ones here are the ones that have been parasitized, and these big brown ones are the ones that have been mummified. That’s when the parasitoid has actually grown inside, created a mummy out of the shell of the aphid, and then hatched out. You can see here just what a high parasitoid load there is—most, over half at least, of those aphids have been attacked by parasitoids. People may think that beneficials can’t actually have that much impact when you’ve got a whole field that’s overrun with pests, but if you’re having a good year and you haven’t sprayed, these beneficials can actually make a huge difference to the pest population. It can actually be the difference between whether there’s any kind of economic damage to the crop or not.

Also, discolored eggs are another sign, though we haven’t got a very good picture for that here because they’re very small. And looking out for adult wasps—but with the idea that they are very small and quite difficult to identify.

So what can we do to protect them? Basically, natural vegetation is going to be a really important part of this. Outside of the paddock, having things like shelterbelts and remnant vegetation can really help to preserve these stocks—not just because it gives them habitat but also resources. You’ll notice with some of these beneficial insects, they’re only predators or parasitoids at one stage of their life cycle. Especially with things like parasitoids—when they’re adults, they often eat nectar, so they need flower resources. That means they need quite a diverse environment in which to survive. If you’ve got those diverse natural native vegetations on the side of the crops, it’s much easier for those beneficials to move in.

It’s important to monitor and use those signs I talked about to see if natural enemies are keeping pests in check. If there are lots around, it means it’s a really good idea to try and hold off spraying a little bit longer to let them have a go at doing their work. You can look at the signs of parasitism and also look at how these pest populations change over time.

And my last point here—which leads into Rob’s talk coming up next—is that if you do have to spray and insecticide use is needed, use the most selective ones that you can—the ones that are really targeted to the pests that you need to control. Really try to limit the use of broad-spectrum insecticides. Rob actually has more insight into this because he’s got more fine-scaled information about which exact chemicals will affect which different types of beneficials. So that is who we are handing over to now. We will definitely have time for questions at the end, so keep writing them into the chat if you’ve got any already, and Rob and I will both join you in answering those questions at the end of the presentation.

Hi, thanks everyone. I assume you can all hear and see me now. I’m Rob, I’m also from Cesar like Lizzy, and I’m going to be talking today about a fairly large research program that we’ve been working on here at Cesar over the last year or so, looking specifically at the impact of pesticides on natural enemies of Australian grain pests. While this is focused on grains, a lot of the findings can potentially expand to other crops as well.

So, my first slide is: what are natural enemies and why do they matter? Which is something that Lizzy pretty well answered. But basically, to sum up—they’re predators and parasitoids. They attack pests. But when we say pests here, a lot of the things that they attack may never actually become pests because of the work that has been carried out by these natural enemies just going about living their lives—predating on or parasitizing the diverse range of organisms that live within and around cropping systems, making it so that they never become a pest in the first place. It’s been estimated that potentially over a hundred billion dollars’ worth of pest control…

Value is provided worldwide each year by these natural enemies—just through yield losses prevented and control measures that farmers don’t need to carry out. So really, really important, just from an economic perspective as well as all the environmental values and that type of thing that Lizzy touched on.

Of course, despite the fact that natural enemies are great, most farmers are not lucky enough to be able to entirely rely on them to control pests. As a result, pesticides are a very important go-to tool for many farmers basically throughout the world. And of course, pesticides are very effective at preventing yield loss—they do their job. They can knock out your pests and protect your crop most of the time, so all good.

Of course, we’re all aware that there are numerous downsides to using pesticides—particularly insecticides and miticides, which is what I’m focused on here. These can include things like resistance, which is where over time populations can evolve to become immune to a certain chemical—particularly if the chemical is overused. As well as secondary pest outbreaks, which is where natural enemies come in. It can be a farmer who has, say, a problem with pest A. You get out your sprayer, you spray your crop—cool, we’ve wiped out pest A, all good, not a problem anymore. But you might have at the same time knocked out a beneficial species—one that you possibly didn’t know was there at all and one that had been happily going around chomping on pest B. And now all of a sudden pest B is suddenly a problem when you didn’t know it was there before. That’s what’s referred to as a secondary pest outbreak. That’s something that we’re really interested in trying to avoid, and it’s something that farmers are becoming much more aware of throughout the world.

This is moving many farmers to adopt Integrated Pest Management (IPM). Integrated Pest Management basically just means applying multiple methods of pest control and trying to find an optimal solution using a combination of measures. This diagram I’ve got here is just the very basic IPM pyramid. The idea is that you want to, if possible, use things lower down the pyramid and only move higher up the pyramid as becomes necessary.

The majority of farmers are doing this type of stuff anyway—even if they’re not aware of IPM as a concept. For example, cultural control—the bottom tier on there—that could just mean things like using resistant cultivars, which the majority of farmers are going to be doing anyway. Physical/mechanical control—same story—that could just be things like basic hygiene practices, stopping pest-infested material from entering your site. Or, for example, if you’ve got greenhouse crops, you can erect physical barriers to stop pests coming in. That’s what we’re talking about when we get to physical and mechanical.

Biological control, of course, is the stuff that Lizzy’s just been talking about—where natural enemies control your pests. This can either happen by itself, just through the natural processes of natural enemies living in and around cropping systems, moving in of their own accord and doing what they do. Or it can happen with human assistance—what Lizzy mentioned—augmentative biological control, where farmers can get hold of certain species of natural enemies and deliberately release them in their fields.

Finally, the top tier—the one we would like to avoid if possible but often can’t—is chemical control. We’d like to use less toxic chemicals before we move on to the really more toxic chemical stuff. Of course, chemical and biological control can be very difficult to reconcile with one another. As I was just talking about—the idea that a chemical that can knock out a pest can potentially knock out a natural enemy as well. So how do we use these two methods together? How do we use the whole triangle if we need to and incorporate biological control in with chemical control?

Well, there are a number of potential solutions. We could do things like carry out strategic spraying—moving away from calendar-based or prophylactic sprays and only spraying based on certain criteria. For example, we could monitor our crops for pests and only spray when they reach a specific threshold. Also, if we have a good understanding of the life cycle of a pest, we can make predictions about when it might be the biggest problem. Many pests’ life cycles are driven by weather, so if we can track temperature over the season, we can get a good idea of when the pest might be a problem and just spray at key times. Or we could also spray strategically in key areas—for example, spraying around the edge of a field as pests are moving in instead of spraying the whole field.

These are all ways that we can spray strategically in such a way as to preserve natural enemies. The other thing we can do—and this kind of gets back to the top tier of the pyramid, the less toxic versus more toxic—is we can use more selective chemicals. That’s what I’ll cover for the rest of the talk here.

So, what we were very interested in doing… sorry, skipped forward too far. As I said, we’re interested in talking about using more selective chemicals, and farmers are really interested in getting an idea of what chemicals they can use that are safer for natural enemies in their fields. The interest has been really big—to the point that guides have been created for two big cropping industries in Australia. Both the cotton industry and the horticultural vegetable production industry have had guides produced for them, shown on the screen here, that are designed to guide farmers in what chemicals they can use that are most compatible with natural enemies.

What these look like—you can see the table I’ve got down the bottom of the screen—that’s an extract from the cotton guide. Basically, we’ve got a matrix with one axis as chemicals (the vertical axis), then the horizontal axis is the groups of natural enemies we’re interested in. In the cells where they intersect, these guides just give a rating as to how toxic that chemical is to those organisms. These guides are super popular amongst their industries respectively, and there was quite a bit of demand from the grains industry for something similar. So that’s what we’ve been working on over the last couple of years.

In order to make a guide like this, what we obviously needed was first to work out what was going to go on those two axes—the chemicals on one and the natural enemies on another. To get an idea about chemicals, we consulted fairly widely with growers, agronomists, and the chemical industry and came up with this list that we’ve got at the top of the screen there. Same with natural enemies—we consulted the academic literature and growers and came up with seven key groups of natural enemies. Obviously, as Lizzy mentioned, there are potentially thousands of organisms out there that could act as natural enemies. We obviously couldn’t experiment on thousands as much as we’d possibly like to, so we basically ended up deciding to pick a few key species out of these seven groups. These seven groups being: predatory beetles, hoverflies, parasitoid wasps, predatory bugs, lacewings, predatory mites, and of course spiders.

Once we had that, this is our nice blank table—blank page, so many possibilities open to us. The first step was to look at what data was out there already. We didn’t want to reinvent the wheel if there was relevant data there. So if there were reliable studies that used similar chemicals at similar application rates as is relevant to the grain industry, we used them. But then to go beyond that, we started carrying out our own research. We were very keen to do research that would be comparable to existing research from elsewhere in the world or other research from Australia—and potentially research that might be carried out in the future as well. We wanted to be able to say: get an idea of how chemical A affects species A, and then if a new chemical comes on the market in the future, we could easily test that and compare that with ours and go, “Okay, chemical A affects species A like this, and this new chemical affects it in this way.” We wanted to be able to directly compare them.

To do that, we followed as closely as possible protocols set out by the International Organization for Biological Control, and we used this device you see on screen, which is called a Potter Tower. Basically, it’s a way to deliver a precision amount of liquid to a certain space. In this case, we mixed up all our chemicals that we were interested in to the maximum registered field rate in grain crops in Australia, along with a smaller 10% rate just to do some comparisons, and used this Potter Tower to apply them to a petri dish at a rate per square centimeter that’s equivalent to the rate per square centimeter that a farmer would apply it to their fields in a real-life situation—trying to mimic exactly what a farmer would do but on the micro scale.

After we sprayed our petri dishes, we gave them about half an hour to an hour to dry and then threw in a bunch of individuals of the various test species—potentially gave them some kind of food supply to help them survive—and then monitored their mortality over the next two to three days to get an idea of how much this chemical impacted them.

So these are our initial overall findings. These are just draft findings at this stage—we’re hoping to have these all finalized in the next couple of weeks. When they are, this table and the surrounding guide will be available for download from our website, so I’ll give you the URL to check back to at the end. But this is what we ultimately have come up with—this big table here. Obviously, there are a couple of little gaps left to be filled, mostly in the hoverflies and the spiders column. These gaps are just there because these are species that we can’t get from a commercial supplier. Lizzy mentioned that there are commercial suppliers out there who will produce and sell certain bugs for you—unfortunately, hoverflies and spiders aren’t in that category in Australia.

So we’ve been having to either catch them from the wild or breed them ourselves, making those two a little bit more challenging. But for most of the rest of it, we’ve filled in the majority of the gaps as you can see.

One of the initial findings I want to draw your attention to—and this was not a surprising finding, but we were glad of it—is this group of chemicals here at the top of the table. These are all chemicals that are generally considered to be either fairly selective or fairly soft. They’re marketed as such, and farmers use them as such. These include things like chlorantraniliprole, which is a selective caterpillar insecticide, and then afidopyropen and flonicamid, which are selective chemicals that target aphids, along with Bacillus thuringiensis and NPV (nuclear polyhedrosis virus), which are both pathogens of caterpillars. What you can see if you look across the table—all these chemicals do indeed seem to be fairly selective. They don’t do much harm to our natural enemies because they’re designed to target certain species of pests. So the fact that we found that to be the case, as many people assumed, was pretty good news for us.

The next one I want to draw your attention to, though, is further down the table—and this one was a bit of a surprise. Gamma-cyhalothrin is from the group of insecticides known as synthetic pyrethroids, and these are generally considered to be pretty nasty, broad-spectrum things that will wipe out most stuff in the field. But if you have a look across the table, there are a few groups there that we found to not be particularly negatively affected by it—in particular rove beetles, hoverflies, and spiders. They all seem to be relatively resistant to this, which was a bit of a surprise. We’re going to do some more research on this, which I’ll touch on at the end, but it was an interesting finding that gamma-cyhalothrin wasn’t necessarily as nasty as we expected it to be.

I also want to highlight the three groups of organisms that seem to be reasonably tough and resilient—those being the rove beetles, hoverflies again, and spiders. As you can see, these are three groups that have lots of green cells on there—fairly low mortality as a result of the chemicals we applied. That’s a good sign for the possibility of these to be used in integrated pest management. It shows that they’re reasonably compatible with a wide range of chemicals.

Just to highlight them a little bit: rove beetles are basically ground-dwelling beetles that prey on a whole lot of things, including thrips and other pests. What’s really good news for farmers is that this is a species that you can get from commercial suppliers. So farmers who are interested in carrying out integrated pest management measures that use both biological and chemical control—if something like thrips is a problem for you, then rove beetles are a great option that are compatible with a wide range of chemicals.

Hoverflies—Lizzy talked about them a bit as well—are also great. They serve as pollinators as adults because they don’t just look like bees, they act like bees. And then their larvae, which I’ve got in the corner there, look like legless caterpillars if I’m trying to be positive about them—but really, they’re maggots because that’s what they are. They’re fly larvae. But they’re really vicious predators that, within the week or so that they are in their larval stage, can eat up to 300 aphids each. And given each female hoverfly can lay several hundred eggs, you can see how much potential one hoverfly has to control aphids over time. Unfortunately, as I said, these aren’t commercially available, so farmers who want to integrate these into their pest management programs will have to do it just by creating the right environment for them. That could include, as Lizzy mentioned, planting flower banks—particularly big clumps of yellow flowers they like, such as brassicas like canola. They love canola and will come and pollinate your crop for you. You can also plant banks of wild brassica flowers around fields, as well as yellow native flowers like big clumps of wattles—they seem to be really attracted to those as well. So once again, another group of organisms that can be used in conjunction with a wide range of chemicals in integrated pest management programs.

So what does this mean for growers? One of the things we can do now that we have this information is that growers can use it to make informed choices about using generally less toxic chemicals. As you can see, a lot of those chemicals toward the top of the chart have a lot of green on there—fairly harmless to most natural enemies. So even just as a base case, if you don’t have time for monitoring or don’t have the resources for it, you can pick a chemical from this list that does the job of controlling your target pest with the least off-target damage. If you’re in a position where you’re able to carry out monitoring or you’ve got good local knowledge about the beneficials in your area, then of course you can tailor the chemicals used to select one that will control the pest while doing the least harm to whatever key beneficial groups you might have in your environment. And of course, this can hopefully be helpful to farmers developing IPM programs that incorporate both chemical and biological control.

So this is where we’re at now. We’re going to finalize this very soon—hopefully fill in the last few gaps very soon. But what then? There are still a few more steps to go in this research. The first one that’s most interesting is looking at sublethal effects of chemicals. We’re particularly interested in doing this for some of the low-toxicity chemicals plus things like gamma-cyhalothrin, where we had a relatively surprising result. What this means is that we want to know what the chemicals can do to an organism even if it doesn’t necessarily kill it. For example, an organism could survive being sprayed by a chemical but then have impacts throughout its life going forward. It might reduce its longevity, which would mean it potentially preys on fewer organisms and is less effective at biological control. It could also reduce its fecundity, causing it to have fewer offspring—again, having a negative impact on biological control. They can even do some quite weird things, particularly with parasitoids, where certain chemicals can distort the sex ratio of offspring. Obviously, with parasitoids, it’s only the female wasps that do the parasitizing. So if an insecticide hits them and they survive it but then go on to have many more male offspring than they normally would, as opposed to female ones, that’s also going to negatively impact their ability to carry out biological control services. So while we’ve got all this data on the lethality of these chemicals, it’s also important to look into the sublethal effects that these chemicals might have. That’s the next step. Going beyond that, we’ll also be looking at chemicals applied as seed treatments.

All the stuff we’ve looked at thus far is applied as a foliar spray, and then we’ll also move on to looking at more realistic field trials going forward. So at that point, I’ll wrap it up. That’s the URL at the top of the screen where we will be posting the table once it becomes available in the next few weeks, so feel free to check back there or flick me an email if you want it and I can send it through when it’s ready.

With that, I’ll thank our partners in this—the Grains Research and Development Corporation, who has funded this work, and the University of Melbourne. I’m happy to hand back over to Lizzy to deal with questions and such. Thanks everyone.

Thanks so much, Rob. That’s a really good summary of the research you’ve been doing over quite a long time now—it’s awesome. There’s actually one question for you in the chat already, which is about the white blanks in the table, which I’m sure you probably anticipated. When are we going to see those white blanks filled in?

Soon—some of them as soon as I finish this talk. I’m going to go back to count how many caterpillar parasitoids have died based on certain things. Most of them soon. Hoverflies and spiders—a bit less soon unfortunately, because we’ve got the only Australian hoverfly breeding program happening in our lab just behind me right now. So hoverflies will happen whenever the hoverflies decide to lay eggs. Spiders unfortunately are probably going to have to wait until next summer because we don’t have many spiderlings of the kind we’re after happening at the moment. But they’re coming soon. The graph with a lot of those blanks filled in—the table—will be online in a couple of weeks hopefully.

Thanks for the question, Richard. Do we have anybody else that would like to throw us a question about beneficials? It’s obviously a humongous topic, and I’ve given you a very superficial overview today. It’s always hard to know what the knowledge level in the audience will be like before you start as well, but hopefully you learned something today. Always keen to go into more detail if anybody has more detailed questions.

Liz, is that the right link for the survey? You’re on mute. Yes, Lizzy—yeah, I’ve just put it up for everybody. That’s to PX—oh sorry, I just copied it onto my browser. Sorry about that. I’ll put that one up and I’ll also mail it out to everybody so they’ve got the ability to answer it through email. Get that on there again—thanks for pointing that out. I mean, I love people going through the PestFacts because there’s lots of good information there, but we’d also love to hear about what kind of webinars you’d like to have in the future. We’ve got a range of different skills at Cesar and we love working with Local Land Services, so always happy to do different types of webinars. Hopefully you can join us for the red-legged earth mite one in March as well. It would be great to hear from everybody because it does guide us for the future. This is a topic that isn’t going to go away—I think it’s only going to get more interest as we go along.

I can’t thank you both enough—I think it was really fascinating. We’ll gather up some resources and send those out in the email as well as the recording once we get that up online. Thank you and hope everybody enjoyed it as much as I did.

Yeah, definitely—thanks everyone for coming. Really lovely to see so many people on board today. You can always get in touch with me and Rob through the Cesar website as well—we’re always happy to answer beneficial insect questions.

Yeah, thanks for having us everyone. Thank you guys—it was great.