130: The Biological Control of Vine Mealybug Using Mealybug Destroyers and Anagyrus Wasps

Vine Mealybug (VMB) is a challenging pest in many vineyards. Growers are increasingly incorporating biological control into their Integrated Pest Management programs by releasing Mealybug Destroyers and Anagyrus Wasps. Brett Chandler, President and General Manager at Associates Insectary explains how these two beneficials help manage VMB populations.

The Mealybug Destroyer (Cryptolaemus montrouzieri) is a predator beetle. It feeds on eggs and small stages of VMB. The Anagyrus Wasp is a parasite. It lays eggs inside the Mealybug. The challenge with the wasp is that they are very susceptible to many chemicals and require more specialized conditions to be effective.

Brett describes how to monitor for both Mealybug and beneficials, when and how often to release the insects, the best release methods, and how to pair beneficials with chemical control.

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Transcript

Craig Macmillan 0:00

And with us today is Brett Chandler, president and general manager of associates and secretary in Santa Paula, California. And thanks for being here.

Brett Chandler 0:07

Thank you for having us Craig.

Craig Macmillan 0:10

You have been in the world of biological control for a long time. And you have seen a lot of trends and a lot of different approaches and a lot of different paths. And the pest that I want to talk about today is vine mealybug on winegrapes, specifically, and I'm very interested in the bio control strategies that people are employing and how they're doing it and how successful they're turning out to be. And some of the advantages of taking a biocontrol approach.

Brett Chandler 0:35

Well, it's actually an integrated approach, where you integrate your chemicals, as a last resort, your cultural practices as a first mainline, and then most importantly, monitoring the insects, both the good and the bad, and keeping a good track on what's happening in the vineyard. And it's much easier than most people think,

Craig Macmillan 0:57

You know, I want to shift to that one point there right away as as one of the challenges is you have to measure to manage, right, that's a common saying. And with beneficial insects, one of the challenges that I always found was how to monitor beneficial insects. I was a field checker for a long time, and I'd find lots of pests, but I couldn't find the beneficials. But we had reason to believe that they were part of the ecosystem, you know, populations would go up and down. And, you know, what recommendations do you have for any particular organism, maybe Cryptolaemus ? For monitoring what the populations are like?

Brett Chandler 1:30

Cryptolaemus, the organism itself is pretty standout, it's pretty obvious. But when it's feeding among the mealybugs, it's very easy to mistake because it's a mimic, it looks just like the mealybugs, and it can be working among there in numbers that you don't notice, unless you really take the time to look at it. What you're going to find with, say Cryptolaemus feeding is you'll find empty egg masses, where you'll see the white fluffy egg mass where the mealybug normally produces it young, but they're actually empty. And that you come to find is easier to recognize, the more often you see it. It's not that technical, but it is something you need to recognize. And through repetition, it's very doable for most most farm employees.

Craig Macmillan 2:14

And again, that's a combination of recognizing the insect itself and also recognizing the evidence that the insect has been there. Because oftentimes, that's what we're looking at is we're looking at the indirect evidence, you know, I should mention, I just dived right in. So the Cryptolaemus montrouzieri is the mealybug destroyer, and is a predator, is that correct?

Brett Chandler 2:34

Correct. It's a predator as opposed to the Wasp, which are parasites, which lay their eggs inside the mealybug. The Cryptolaemus beetle actually feeds on the eggs and consumes mass quantities of the eggs and smaller stages of the mealybugs. It's a it's a predator like any other that is not attached to any one stage, but feeds at all stages available to consume.

Craig Macmillan 2:58

Tell me a little bit about predators. I mean about parasites next.

Brett Chandler 3:01

The parasites, they're a very unique creature. They're highly specialized, they will only feed on one or two species where they can find and lay their eggs. Only the females do the feeding, the males do no feeding, they simply breed and provide no control. They are also very susceptible to many chemicals that the beetles or other predators may be less susceptible to. They also are very host specific. In other words, if there's not enough of the pest around, they won't find it and they may starve. If there's too many, they may be repelled, or they don't like them at that high density. So they're a very, very specific tool for a very specific circumstance. But broadly, the need to be used in only specific locations and times of year because they're they're quite delicate.

Craig Macmillan 3:55

You mentioned feeding. I thought the parasitoid wasps just lay their egg in the adult. And then it was the larva yes that had hatched out that does the damage. Is that right?

Brett Chandler 4:08

Well, actually, it does both. It's called Host feeding. And host feeding occurs in some cases where they're not getting enough protein. And they may feed on one because they'll find a mealybug and if it's too small or too large, they won't lay their eggs on it. But they may kill it by feeding on it or merely annoying it. Actually the Asian citrus psyllid parasitoid tamarixia, it kills twice as many by feeding than it does actually laying eggs.

Craig Macmillan 4:34

There you go, that it's fantastically interesting. If I'm trying to monitor for the wasps. How do I go about doing that? Because they're tiny.

Unknown Speaker 4:42

Very, very difficult. But again, early season, they're going to be laying their eggs inside the smaller mealybug and it's very difficult to find but once the first generation has passed, and the adult Wasp has emerged from what we call the mummy, where the egg has crawled out and become an adult fed on the mealybug. And emerged by chewing a hole just like a chick, choose a hole in a chicken egg, you see that characteristic round hole in the mealybug pupa. And that tells you that an Anagyrus adult emerge from that pupa.

Craig Macmillan 5:16

When we think of pest monitoring, and we think of densities, and we count or we quantify somehow, and then we come up with changes over time. Maybe we do our timings or pesticide timings, maybe based on that or decisions, whether we use pesticides at all based on that. What are the ways of measuring density? And what kinds of density measures do we use and thresholds to use for deciding Yes, this is really working well. Or maybe I need to do an augmentative release.

Brett Chandler 5:44

Well, for both of these, this is not an established what classic biological control where you release once and allow it to come on. The insect and the Wasp with the mealybug have what's called a dynamic equilibrium where it takes them time to bring the population down. And so that time may be too long, where the grape clusters are infested with the mealybug. And you don't allow that to happen. So you use the technique called an inundated release, where you release many more than the natural population would be in hopes of bringing down the climbing population because the key to control is actually the second generation of these insects that are released whether wasp or beetle, not the first generation. A wasp can lay 100 to 150 eggs, a beetle can lay up to 400 eggs. So that's 400 times the control in the second generation than the first.

Craig Macmillan 6:39

And how do we distribute these in the field? What's the what's the method by which both the beetle and the Wasp are introduced?

Brett Chandler 6:46

Many methods can be used. Drones are much more popular now and being used. The drone pilots are quite quite adept at getting them where they need to be when they need to be. We work with companies like Parabug, who are quite familiar with working with the beetles and depositing them quite a bit in the Central Valley forests and other growing locations and the Wasp as well. Hand releasing can if you have a clumped distribution, where you only have pockets, hand release is probably better if you have it broadly where the vine mealybug is broadly throughout the vineyard, a drone is helpful. But drones can be expensive to come for just five or 10 acres, you need to get a large acreage to make it effective where several neighbors get together and the neighboring vineyards all working together to allow it to happen. Drone pilots have to travel, their time. So to be cost effective, you need a larger acres for the drone. But at the same time, you need manpower available to release by hand as well.

Craig Macmillan 7:43

So for dropping a beetle, we're dropping as an adult?

Brett Chandler 7:48

Yes, we ship the beatles as adult their wings and they can fly. So when they come out, they'll drop a little and start flying and working towards the vine. And settle on the line, if there's any mealybug in the area, they will immediately be olfactory stimulated to search for them. They smell the mealybug and that's one of the driving things that attracts them and keeps them in the vineyard. Feeding as long as the population is is active.

Craig Macmillan 8:49

Is that true for the Wasp as well?

Brett Chandler 8:49

The Wasp is more of a solitary searcher, they like very small numbers when the vine mealybug are just emerging from under the bark or maybe on the edge. When high numbers of vine mealybug come out, they unfortunately attract the ants and the ants are the downfall of the Anagyrus. Anagyrus goes from very effective to about 2% effective when the ants are active in the in the vineyards. It is a big limiting factor of theirs. Whereas the Beatles because of their mimicry, they even smell like the mealybugs, and the ants will ignore the juveniles. Once the adults have laid the eggs, the ants will ignore them. And they can feed and control the mealybug with no disturbance from the ants.

Craig Macmillan 8:55

Interesting. Is there an advantage to using both types of organisms?

Brett Chandler 8:59

You can if you're properly timed in high numbers mid season, the beetles are definitely better because they're more effective. As far as bringing down high numbers and a little more tolerant of active spray programs. If you're using mating disruption that works very well. A recent study showed that beetle feeding is actually stimulated by the odors of mealybugs by the female pheromone and it actually stimulates their feedings. So it not only collaborates but it's actually a synergistic effect if you're using pheromone systems like the CheckMate or something like that. And if you're using trapping, that also helps you to time your initial releases of your parasitoids where you want to get them out there very early and as about a week after your first flight is a good time to plan to release. The problem is you don't know exactly when that is and that's the biggest problem is the lead time to get these insects grown. It's about 80 days for the Wasp and about 105 days for the beetles where we have to have those on hand and have started growing them 100 days before you need them. And that's that's the limitation, they don't have a long shelf life.

Craig Macmillan 10:10

So tell me more about the rearing, I think this is really fascinating.

Brett Chandler 10:13

The rearing system is actually rearing on live mealybug host, we rear ours on citrus mealybug, which is a similar host to vine or grape mealy bug, but not problematic if it should escape. So we have large colonies of millions of mealybugs in enclosed spaces, where we raise them to high densities, let the beetles go in the rooms, the adults lay their eggs, feed, reproduce, those 500 400 eggs hatch out, and then we harvest them out of the room, put them in bottles, and ship them to growers. And we've got about five to 10 days from harvest to use them so that they're still strong and vital. That's why we can't hold them over really from more than a week.

Craig Macmillan 10:55

So do you have like phases, you have different different populations that are kind of different stages, so that you can kind of hit the windows as you're going forward? Because otherwise you'd have everybody coming online at 105 days. That'd be like, okay, we got five days to do all the business in the world. Let's get them out there now. You must must wrap it up somehow.

Brett Chandler 11:15

Yeah, you're exactly right, we start logistics in January, and start talking to growers all the way up as far as Napa is down as far south as Delano, and everywhere in between. And if you'll notice, the vines come on at different times along that gradient as well as you run north to south. So that staggers it a little bit. But May and June are we're swamped. We're selling every one we can grow and working to grow more each year. So we do have to stagger them. And we do have almost 50 rearing rooms, where we have cycles coming off every couple of days. So we have fresh every couple of days. So it's continually going on a year round basis. And interesting thing this winter has been we sold tripled the number of beetles this winter than we normally have. And it's just taxing our staff to the maximum. So unfortunately, this year, we are not going to be rearing the Anagyrus Wasp, we simply don't have the manpower for it this year. I believe there's another source for those that's available. But the beetle demand is so strong, we're doubling our population from last year and thinking we're going to need to double it again to make it available because demand is so high.

Craig Macmillan 12:24

So this is really been adopted?

Brett Chandler 12:25

Very much very much. We've been doing it for about 10 years up in Napa and about eight years in the Central Valley and then scattered through that in the Central Coast. And it's becoming more and more driven by the the customers the end customers that want to see a sustainability component to the grapes going into the system. And also a big problem shifting towards the Beatles is the big problem has been for the Anagyrus has been the loss of Lorsban. Chlorpyrifos was actually a very good IPM tool that could be sprayed at the base of the vines to keep keep the ants at bay and allow the Wasps and the Beatles to do a better job. And with this loss, and not a great replacement on the horizon, people are having to use more and more than they did at the past. I mentioned about the Anagyrus dropping off, it drops about 75% and effectiveness when ants are present. So as ants come up, you need many more Anagyrus to get the same concentration in the past. And same thing with the beetles which were treating a lot more acres than we had but also more per acre.

Craig Macmillan 13:32

So there's no overwintering of either of these organisms?

Brett Chandler 13:37

There actually is. As far up as as in Tracy and Lodi area, we've had some overwinterings in most winters. The problem is the numbers are so low, that it's hard to get them going in the spring. You kind of have to kickstart it, but we do get carryover particularly along the coast, we get a lot more carryover. But the wasp, the populations dropped so low, it's very, very difficult to get much carryover with that. So seasonal inundative releases, which is what we've used in citrus for almost 100 years. We've been growing these beetles here for just about 95 years, and they're a great supplement to your pest control. You can't expect classic, practical,complete biocontrol in a crop that is not a naturally occurring ecosystem. There's not an ecosystem somewhere with 100 acres of perfectly uniform vines all coming in at the same time.

Craig Macmillan 14:27

Yeah, yeah, no, absolutely. And so this is not a refugia issue. It's not like oh, if I just had the right you know habitat for them they would establish and hangover it's that isn't that's not really a strategy that would work either populations in place.

Brett Chandler 14:42

In most areas you can get a few but the refugia is, can be problematic. They like soft bodied pests, the beatles particular and the mealybug you're not going to get mealybug to produce over the winter they go underground or under the bark so there's simply no food available for the wasp. But the beetle will feed on many soft bodied insects, reproduce on several species of mealybugs. But truthfully, there's not much activity during the winter months, and they have to kind of settle down and it takes them a while to get up to numbers and the pests being, taking advantage of that get jump started in the spring. So if you could get caught up, but you may be on your economic threshold, and they may be in your bunches by the time you get that done.

Craig Macmillan 15:29

What is the integration of cultural control, cultural practices, biological control, chemical control? So the, you know, the classical IPM framework. What do you see growers doing in terms of that integrated approach that's working well, not just for the control the mealybug, but it's also making it possible for these other practices to work well?

Brett Chandler 15:51

Well, the control of the ants through either minor cultivation, or banding with sticky, sticky materials on on the poles and on the lines to exclude the ants. Cultural practices as the're pruning to flag where it was a problem last year, you got those black vines, you've got sooty mold residues so that it combines to catch your eye particularly at this time of year at budbreak. And early in the season. flag that. That's going to be where you're going to see your activity first. And you can have a reward to your pruners to your irrigators to weed people working. Give them the flag and they come back and show you how many they did and you buy them lunch, something like that. Anyone can notice the black stains, you don't have to be highly educated. Then you concentrate your scouting on those black spots rather than having to canvass the entire vineyard. Where the black spots are is where you're gonna see the problem emerge first. Later in the season for spread, you'll have to spend more time. But that's a good economy of time, is to allow everyone that goes through the vineyard to have a part in monitoring.

Craig Macmillan 16:59

And then I can target what I do, whether it's a release or, or whatever. How to pesticides come into play here? Because I think there's always a conflict between biological control agents and pesticides.

Brett Chandler 17:12

We found a good solution in the citrus which seems to work in the grapes just as well. Particularly with newer products like Movento, Spirotetramat, very soft on beneficials, goes into the tree provides long control, goes into the vine provides long control, is not particularly disruptive, has very low surface residue. We found the mealybug and the Cryptolaemus aren't too disrupted by sulfur sprays either. And they do pretty well there. Abeamectin sprays for mites seem to do pretty well. Some of the plant growth regulators though can be quite hard on the beetles. Like Esteem. They will impact them as well. So that is something although it's considered safe for parasitoids, it's not safe for predators. And so we want to watch those when you combine those. Imidacloprid doesn't seem to do too much of a problem with when that's chemigated in or even applied on on a surface surface treatment. We just tried to time the releases to say a week after after your application of something like that, or a few days before a sulphur spraying. By timing it allows the beatles to find it, lay their eggs, which they will almost immediately, same with the wasps. Having something blowing dust. Even if it is just sulfur dust is highly disruptive, no one would want to have a bag of dust blown on them. And so just the disruption breaks down their activity. So giving them a few days of free time to get used to the odors, detect the mealybug find them do their feeding or their egg laying before you have to pass through again. So the calibration and the timing and the synchronization between your scheduled sprays is is it's usually not too hard to do but it does take a little forethought.

Craig Macmillan 18:53

You might have mentioned this but I'm not positive, we're talking about a release in the spring. They're not additional releases after that, it's a one release per year.

Brett Chandler 19:02

Actually not. The Anagyrus are so expensive to rear the high numbers aren't practical and so many are lost for various reasons that they release about every two weeks up to eight times a year. The Cryptolaemus we do an initial release at a base number and then a follow up release if it's if it's needed by by scouting and and about 50% of the time it's needed. So Cryptolaemus maybe once maybe twice, antivirus up to eight times. So there's a lot more work involved in the Anagyrus. So and they're more expensive. So you want to make sure you're using an expensive tool like that to its best effect. So if you have ants, Anagyrus are not recommended.

Craig Macmillan 19:45

Now we talked about the fact that overwintering isn't really practical, but what things can I do during the season to encourage protect, promote the beneficial insects that I've released?

Brett Chandler 19:54

Very simply the some of the broadleaf plants, some of the lupins and things like that will, if allowed to grow near the vines, will offer a little alternate nectar and a little food if the numbers are getting low for the beetles. The wasps, they will host feed. Like I say they're much more delicate, and it's hard to keep them around. That's why the constant releases during the year because of multiple overlapping generations, they're only feeding on about four days out of 30. Of a 30 day lifecycle for the mealybug, only four days that mealybug appropriate to be stung. So trying to get that you're releasing constantly to provide some loss there at every stage of the life. So that one wasp finds its mealybugs every couple of weeks. The main thing is to keep the disruption of the harsh chemicals to a minimum, or at least timed and coordinate with your insectary. The other thing is coordinating with your insectary and getting to know your supplier. Ask them do you have you know, customers already booked for this time. You know, historically, when when you've first seen it each year. You know historically, when your bunches normally close up, and when you want to get it in there. Follow the the history of vineyard and have it in your mind when you speak to them and give them a target window as early as possible. And they will work with you. You may have to shift a week or two, like I said one way or the other because of availability, but we're constantly expanding production to try and supply everyone as needed. But it's the growth of this. It's grown 30 40% In the last two years in demand, and it's just quite a quite a tough talent to find people that know how to grow insects to hire them. There's not a job board you put up and say, recruiting insecr rearing people, come on over.

Craig Macmillan 21:37

What is your experience? What are growers telling you? This sounds like this is a grower to grower explosion. Talking to people and I'm like. So what are you hearing back from growers that's making them so excited or making them really recommend this to their neighbors?

Brett Chandler 21:52

It seems that they see results. But it's very difficult to quantify an exact percentage, but they're they're satisfied with it. We had one grower who started out and promised he would buy from us if we wouldn't tell anyone he was using them. He thought it was a competitive advantage. And he wanted to keep it a secret from his neighbors because he thought he had one up on them.

Craig Macmillan 22:16

Meanwhile, the pressure of spread from across the fence line continues. I can see that I get you know I can I can see the mindset there. It makes sense. It makes sense. That's one thing I've always loved about this industry, and I've learned about Ag in general is how kind of collaborative it is. Insane things in the wine side, people ask me, you know, oh, or you know, how cutthroat is it? And it's like, well, there is competition, but also everybody's in the same boat. We're all facing the same problems. It's all the same time. You know, I mean, we're kind of a community regardless. With that idea, are you finding, is the spread of information, is this via meetings? Is it just one to one? Is there press stories that have made a difference? I, I'm just really curious about this as a model for other kinds of sustainable technologies.

Brett Chandler 23:01

It I think it's a combination of both. But the onside demonstration, the Lodi, grape growers have have had onsite demonstrations of drone releases for everyone to see. Things like the the Ag Expo, it's been going on and talking about that Kena Daane's been talking about it for several years. But now the practicality of it is really coming forward because people were scared that it was a lot more work. And it's not really. But it is it is a different kind of work, and it is practicable. But it does produce good results. And that's why the growers are coming back year after year to us and buying more each year. I don't think they'd be wasting their money if if they didn't think it was effective. And it seems to be that they're quite satisfied with with the results they're seeing in all aspects of it.

Craig Macmillan 23:48

Are there new things on the horizon? Or things that have just kind of happened recently that are exciting? Are there other organisms that have potential or there are other methods that are starting to show us potential? Do we have new information about the fine mealybug we didn't have before?

Brett Chandler 24:02

You'll have to talk to Dr. Daane about that. Kent knows all the details. I know he's working very hard on it. And he has been for many years. As I say, I think the drone technology and the practicality of the drones is making it more practical to people. Because whether it's an insect or a vineyard, you don't have people standing around, you're usually short handed, especially now. And the drones allow them to also to cooperate them with themselves and their neighbors and work among themselves to have the drone come in and do large scale releases. And that frees up the labor and they may take a few and do some a couple spot releases, but overall they can do broad releases and introduce them to an area, frankly the way we have done with the scale parasites in the citrus for 65 years. And the innondative, area wide approach brings it down and tends to expand overall control. While it's hard to tell on an individual vineyard block or orchard the overall regional control, you'll see it effectively as the numbers begin to drop. As long as we can keep good control of the ants. The ants are a plague in the citrus as well and a huge problem for us. And we use the Lorsban as well and founded quite an effective IPM tool, and we're looking forward to some useful replacement on the near horizon.

Craig Macmillan 25:18

Is there a biological control agent for their Argentine Ant?

Brett Chandler 25:22

They've tried. The thing is a super colony, believe it or not, in other parts of the world, two colonies from 50 yards apart, will fight each other. But most of Western California is one super colony of Argentine Ants that cooperate and feed. They actually keep the Fire Ants out. Where they have controlled them. The Fire Ants come in and they reduce the control and the Fire Ants are decimated by the Argentine Ants in Southern California.

Craig Macmillan 25:49

That's interesting. That's really, really interesting. Well, I want to thank you for being our guest today. This has been great, a lot of great information and some kind of hope, I feel. It's exciting when we get biological control success. At the beginning of the philosophy, like you said, going back 100 or more years ago to classical approach, we had a couple of successes that were really, really exciting. And then people kind of discovered how difficult it was. And I really appreciate folks like you and the rest of the community that keep sticking to this idea, and finding ways to make it work, because it's a fantastic strategy, and it has its place may not be perfect, but man, it makes a huge difference. And I think that's really great. I want to appreciate that. So I want to thank our guest, Brett Chandler, President and General Manager of Associates Insectary for being on the show today. I look forward to seeing you again. It's been a few years before just bumping into you in person again.

Brett Chandler 26:40

I hope so. Craig, look forward to seeing you soon. Thank you.

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