Haley Catton, a research scientist with Agriculture and Agri-Food Canada at Lethbridge, says producers need to focus on conserving beneficial insects while simultaneously managing pest insects.

“There are two basic rules: don’t hurt them, and try and help them,” Catton told the Farming Smarter conference and trade show in Lethbridge last month.

Many beneficial insects help to promote synergies and make the most possible use of other ecosystem service providers. Examples are predators and parasitoids, pollinators, microbes in the soil, decomposers and earthworms that improve soil structure and water filtration.

“There are a whole bunch of these things, and any management decision I make, it’s best to consider on a holistic lens, doing the same whether it’s tillage, irrigate or whatever. Considering them in context of all these different things will be the best decision,” Catton says.

“They call that eco-stacking — stacking this on top of that. Stack the beneficials on the soil microbes, think of it all. I don’t envy farmers, actually, because you have so many decisions to make, and some of them are on a short timeframe. Some of them are on a long timeframe, some of them affect your fields, some may have an effect on regional pest populations.”

Beneficials in the field are either predators or parasitoids. Predators include ladybird beetles, ground beetles, lacewings, syrphid flies, aphid midges and yellow jacket wasps that chase down the cutworms and eat grasshopper eggs.

Parasitoids, meanwhile, lay their eggs inside an insect host such as a cutworm, and the babies will eat the cutworm from the inside out.

“These things are massively important. Beneficials kill pests, they scare pests and change their behaviour,” Catton says. A cereal leaf beetle, for example, “will drop off the leaf if it is scared of a predator, and they eat and poop, which is part of nutrient cycling.”

For wheat stem sawfly, a pest on Prairie farms for more than 100 years, Bracon cephi is a parasitoid.

“It is killing a lot of your sawflies. The adult looks like a wasp and she lays her egg in a wheat stem and the larva feeds inside the wheat stem. That parasitoid will find stems with sawflies in them, sting them from the outside, paralyze the larva, and its babies will eat that larva alive,” Catton says. “It’s actively preventing cutting from your fields, but it’s small and it’s out there.”

Prairie field beneficials are also numerous, with plenty of diversity.

There are more than 200 species of ground beetles in Prairie fields. In recent biodiversity studies, 62 such species were found in Vauxhall plots over four years and more than 37 were found over two years at Lethbridge, while another study Catton is just wrapping up found 82 ground beetle species.

It can be difficult to put a dollar figure on the work done by these beneficial insects, Catton says.

“There are so many variables going on. When a problem is prevented — say, an aphid population is prevented from outbreaking because those ground beetles, those beneficials are eating them — a prevented problem is an invisible problem. There is a lot of work being done by these beneficials that we don’t even notice because it’s not being quantified.”

Catton encourages producers to avoid hurting beneficials by not using insecticides unnecessarily. This can be accomplished via scouting and following economic thresholds. Producers who do need to use insecticides can apply “soft” versions and make sure not to use them when beneficial insects are most vulnerable.

“My talk is not about pollinators, but one way of thinking of protecting pollinators is to not spray when they are out flying, not during those daylight hours,” Catton says.

Averting harm and helping beneficials can include offering an alternative habitat with shelter, nectar, alternative prey and pollen. Finding that balance between weeds/pests and beneficials is key.

“It is good to have some pests around. If you sanitize your fields with no pests, then the predators have nothing to eat. You want low levels of pests around.”

Pest management is a tool box, with many tools available to diversify control, be they cultural, physical, biological or chemical.

“It’s important to have different tools because if all you have is a hammer, then everything looks like a nail,” Catton says, referring to the beneficial and unwanted insects.

“Cultural controls are crop rotations, physical controls are trap crops, biological controls are beneficials, and it interacts heavily with the insecticides. When you spray a pest, most of the insecticides we use are lethal to those beneficials, too.”

The International Organization of Biological Controls has been compiling a list of “softer” insecticides. While not currently done in Canada, Catton says Australian researchers used that data to compile a pesticide toxicity table for beneficials, publishing a paper in 2024.

“They did find some main messages that some insecticides are consistently harder than broader-spectrum and some are soft,” Catton says.

For more informtion about beneficial insects, visit fieldheroes.ca.

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Although producers such as Dallas Leduc and Corey Loessin in Saskatchewan and Roger Chevraux in Alberta appreciate the fact they can now again use Syngenta and Adama products with lambda-cyhalothrin chemistry to control insect pests on cereal, pulse, corn and canola crops, they say it’s been a tense and somewhat expensive past couple of growing seasons without use of the effective and affordable insecticides.

“We got through the past couple years without any major wrecks,” says Roger Chevraux, who farms at Killam in central Alberta, east of Camrose. “We did have alternate products available, but the issue is when the registration of lambda-cy products changed we had very little notice. If we had had a serious outbreak of some pests it could have been a disaster.”

Corey Loessin, a grain, oilseed and pulse crop producer at Radisson, Sask., credited commodity organizations such as the Canada Grains Council and others for their efforts in encouraging PMRA to review current data that helped to reinstate lambda-cy registration for major crops.

And Dallas Leduc, who farms at Glentworth, says grasshoppers didn’t take a break during drought conditions in his part of southern Saskatchewan. Fortunately he was able to use another insecticide — Coragen, with the active ingredient chlorantraniliprole — which was effective but considerably more expensive than lambda-cy products.

As well, he did discover a cost-effective, made-in-Saskatchewan insecticide that also has become another tool in his crop protection toolbox.

The background

At issue for these and other Canadian farmers was a decision by Health Canada’s PMRA in mid-February 2023 to change the registration of insecticides containing lambda-cy chemistry, saying those products could no longer be used on major crops such as cereals, pulses and canola — if those crops were being used for livestock feed. Lambda-cy could still be used on crops to be processed for the human food market.

The ruling followed a routine review of pesticides in both the U.S. and Canada, which started some years before. PMRA made its determination due to concerns about insecticide residue levels found in livestock feed.

Ultimately the existing lambda-cy products, such as Matador 120 EC and Voliam Xpress from Syngenta, as well as Silencer and Zivata insecticides from Adama, remained available for food crops, with their labels adjusted accordingly.

But as the agriculture industry knows, crops seeded in April and May might very well be intended for human food products, a plan that could quickly change depending on growing season conditions, markets and crop quality at harvest. Any of the major crops could very well end up as part of some livestock ration.

Fast forward to earlier this month: after reviewing the most current research data regarding pesticide residues, PMRA reversed its decision and reinstated the use of pesticides containing lambda-cy chemistry on major crops used for both food and livestock feed.

The 2025 ruling does have a couple of limitations. Lambda-cy products can no longer be used on peach and apple crops. Lambda-cy can be used, but with reduced application, on turf grass — but it still cannot be used on any crops produced for livestock forage, whether that be grazing, greenfeed, hay or silage.

The 2023 scramble

“The PMRA ruling was made in mid-February of 2023, which didn’t leave chemical companies or farmers much time to line up alternate products for that season,” Chevraux recalls.

“And the ruling itself made zero sense. Why could the products be used on and be OK for food use but not for feed? It just didn’t add up.”

Chevraux, a past chairperson of Alberta Canola, says he doesn’t always need to use an insecticide — but in the spring of 2023 he did have a problem with cutworms on his farm.

“Fortunately we found another product that helped control cutworm, but it cost four times as much as the lambda-cy products,” he says. “We did have some flea beetles, but it wasn’t serious. We were just lucky there wasn’t an outbreak of grasshoppers or diamondback moths or some other pest that can blow in from the U.S.

“I get concerned any time we lose a tool from the toolbox, because in agriculture we need as many choices as possible in order to optimize production,” he says. “I believe PMRA needs to operate in a more timely manner. The agency needs more funding, and I don’t believe the agency has a good understanding of the agriculture industry, our modern production practices and some of the issues or challenges the industry faces in any given year.”

More responsive PMRA

Loessin says farmers in his area northwest of Saskatoon fortunately also didn’t have any major insect outbreaks during the 2023 and 2024 growing seasons, and they did have access to alternatives as needed.

“I’m glad that use of lambda-cy products on crops used for livestock feed has been reinstated,” says Loessin. “But in my view, it just corrects a mistake that shouldn’t have been made in the first place. It appears that PMRA was relying on old data when it made that ruling in 2023, even though there was new or more current data available.

“Commodity organizations actively encouraged PMRA to reconsider and review the new data which eventually led to the products being re-instated for use. The initial review started in 2017 and now it is 2025 — that’s a long review process.

“In general I believe PMRA needs to be more responsive. It took two years from 2023 until now to review the data and reinstate these insecticides. What if it had been the opposite issue — there was chemistry in use that was causing harm to human health or the environment? Would we have to wait two years for that product to be pulled from the market? I’m glad the lambda-cy products are back but I really think PMRA needs to be more nimble and more responsive in its review process.”

Good to have alternatives

Although Leduc says he was able to use alternate products to control insect pests — namely grasshoppers — on his southern Saskatchewan farm, he’s glad to see products containing lambda-cy can again be used on cereals, pulses and oilseeds for both food and feed markets.

“Coragen is a great product, but it is more expensive,” he says. “Depending on the pest and the year sometimes we have to treat whole fields or sometimes just the edges or the headlands. We went into the fall of 2024 with no subsurface moisture so I know that grasshoppers will be a problem again in 2025.”

One other grasshopper control option Leduc discovered over the past couple of years is Eco-Bran. Developed about 40 years ago by Peacock Industries of Saskatoon, it’s a bait made of wheat bran infused with carbaryl insecticide.

Leduc says his spot application system uses a hopper with a fan powered by a five-horsepower Honda engine, mounted in his pickup truck.

“We found that sometimes we just want to treat the ditches or the headlands, or just around the yard for grasshoppers,” he says. “And some of our land is up to 30 miles away. We can mount the blower in the back of the pickup truck, drive 30 minutes to the field, put the Eco-Bran in the hopper and blow the product out in the ditch or along the edge of the field and then drive home. It is a lot simpler than taking a sprayer that costs a few hundred thousand (dollars) and bouncing it along for 30 miles for a 20-minute spraying job.”

What’s more, “it works, too,” he says. “The grasshoppers eat that bran and they’re dead. It doesn’t eliminate them, but it does help to control them. It is environmentally friendly and an effective way to treat strips or patches.”

Eco-Bran comes in a 20-kg bag that retails for about $147.

A cautious approach

Manitoba Agriculture entomologist John Gavloski says the pesticide review process can sometimes result in restricted uses of popular pest management options — but it’s a safeguard against product uses where there’s evidence of potential harm to the environment or human health.

PMRA, he says, wants to make sure insecticides used at recommended label rates do not exceed maximum residue levels in our foods.

“The PMRA is taking a cautious approach when it comes to regulating the uses of lambda-cyhalothrin,” he says. “There was some concern that residuals in some foods were found to be above what is considered safe levels. Now PMRA has reviewed new information and determined that some restrictions on the use of seeds from some major field crops being used for livestock feed can be lifted.

“However, PMRA still has concerns about these crops being used as forages, so the restrictions for that end use is still in place.

“Overall it is good news for farmers, in that they can use these effective insecticides on major crops, such as canola and some cereal and pulse crops, without concerns around marketing grain from these crops.”

Gavloski notes lambda-cyhalothrin use also remains cancelled for sunflowers, which took up about 44,900 acres in his province in 2024, down 47 per cent from 2023.

“Unfortunately, there aren’t a lot of insecticide options that can be used to control lygus bug in sunflowers, but producers and the industry were able to obtain emergency registration of an alternate product that could be used,” he says — a reference to Carbine, a flonicamid product sold in Canada by FMC. That emergency registration is still in effect in Manitoba, and for confection sunflowers only, but is set to expire July 20.

“There are now efforts to obtain full registration for this product for use with sunflowers. On the positive side, this new product is very selective in controlling lygus bug and other sap-feeding pests and will not harm beneficial insects. So that is perhaps also a good outcome of this review process.”

System needs a review

Shannon Sereda, senior manager for government relations and policy with Alberta Grains, says Alberta farmers are no doubt pleased with the recent decision by PMRA — but it underscores a need to look at the whole process of how pesticides are reviewed.

“As everyone says, it is great to have another valuable tool back in the crop protection toolbox,” Sereda says. “This is what Alberta Grains was advocating for all along and it is the outcome we had hoped for.

“But it emphasizes the need for industry to work with PMRA on hopefully revising and modernizing the whole pesticide review process. The process takes years and to have restrictions like this imposed for two years creates a lot of confusion for producers.

“The decision which separates food from feed is a very complex issue for farmers. Often the decision regarding the end use of crops isn’t made until long after a pesticide has been applied. So we feel it is important in making future decisions that PMRA understands the complexity or the ramifications of their decisions and importance of timeliness. These are some of the concerns we as a sector will be looking at with the PMRA review process.”

The issue with lambda-cy also emphasizes a long-talked-about need for harmonizing the whole crop protection product registration process among like-minded jurisdictions and markets.

U.S. authorities, for example, had reviewed data and found lambda-cy products fell within food and feed safety guidelines, whereas PMRA had to conduct its own review and evaluation.

The issue with the part of the PMRA decision that restricts the use of lambda-cy on forage crops remains up in the air. However, one southern Alberta agronomist says it may not have a huge impact.

George Lubberts, owner of Complete Agronomic Services at Nobleford, north of Lethbridge, says irrigated cereal crops grown for pasture, greenfeed or silage usually aren’t treated with pesticides, although pests such as grasshoppers can be a concern for dryland farmers, especially in dry growing seasons.

“Among my clients, I believe the restrictions in pesticide use might be a concern for dairy producers looking to control alfalfa weevil in alfalfa crops, but there are other products available,” he says.

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“They seem to like it a little bit cooler, rather than very hot, and can suffer with great heat and very dry conditions,” Saskatchewan Agriculture entomologist James Tansey says. “That can give us a little bit of predictive power as far as their distributions and prevalence in the year ahead.”

Adult cabbage seedpod weevils (Ceutorhynchus obstrictus) feed on a wide variety of species in the brassica family but complete their larval development only in the seedpods of certain species of Brassicaceae, including canola.

Typically, there is a strong correlation between the ebb and flow of insect populations and their natural predators. But in North America, cabbage seedpod weevils have no natural predators.

“Because it is an introduced animal, it has escaped the regulation that it might normally experience with its natural enemies,” says Tansey, who did his master’s thesis on the bug.

Expanding range

The insect species originated in Europe; its documented debut in North America was in the Creston Valley of British Columbia in the 1930s.

“The thinking is that it worked its way south into the United States and found its way around the mountain system there into Alberta,” Tansey explains. “It was first detected in the Lethbridge area in 1995.”

The good news, said Tansey, is that a federal research station in Lethbridge staffed with some very capable entomologists identified the weevil as a potential problem for farmers and started the work to develop strategies to combat the pest.

But the bugs kept moving.

“From that point, it was an overland march,” Tansey says. “It’s a decent flyer, and it also hitchhikes in vehicles. It can travel relatively large distances in relatively short times, and by the early 2000s, it found its way into Saskatchewan.”

By the time it reached Saskatchewan, it was already well established in southern Alberta, causing economic woes for canola growers in the province.

The weevil is also making its way into Manitoba. Provincial ag entomologist John Gavloski has been carrying out surveys in Manitoba to spot the bug. According to his 2023 survey, cabbage seedpod weevil levels are still very low and well below economic levels in Manitoba. However, with every survey, the weevil’s range expands eastward.

There is an eastern population of cabbage seedpod weevils that is well established in Quebec, Tansey adds, but it’s thought to be a separate population from the one that was first spotted in Creston.

Life cycle

According to the Canola Council of Canada, the adult weevil overwinters in the soil, often under leaf litter in tree shelterbelts, roadside ditches and woodlots. They emerge in the spring, with peak emergence occurring when soil temperatures reach around 15 C.

Following their emergence, adults fly to patches of early-flowering plants in the brassica family, like wild mustard and volunteer canola. They move into canola fields in June, when the crop begins flowering.

“The nice thing about this particular insect is that it overwinters as an adult, and it’s really attracted to the colour yellow,” says Keith Gabert, the council’s insect management lead. “We tell them to check the earliest flowering fields, and without a doubt, the cabbage seedpod weevils in the neighbourhood will be attracted to those fields.”

Management

That predictability is what makes the cabbage seedpod weevil relatively easy to control.

“This is a pest we have learned to manage,” Gabert says. “We’ve had several decades of dealing with cabbage seedpod weevils. It really seems to make itself at home south of Highway 1 in and around that Lethbridge area, and growers there have considerable experience dealing with infestations.”

According to Gabert, the cabbage seedpod weevil survey maps provide a good indication of where infestations are likely to occur again.

“The maps are pretty clear that southern Alberta may have a population there, but it isn’t as far north as we’ve seen it in the past,” he says. “There is also a small hot spot west of Swift Current and a small hot spot east of Regina.”

Farmers in or near those areas should be actively scouting for the pests, particularly if their canola field is the first to flower. But Gabert warns farmers not to jump the gun when spraying for the insects. While they might be present in large numbers in a flowering canola field, they cannot do any economic damage until the plants are podding.

“You can have a lot of cabbage seedpod weevils on those yellow flowers and get excited,” he said. “But just step back a moment. If you don’t have a pod that’s half an inch long, it’s not big enough for them to lay an egg and can’t do any damage.”

If you can hold off until that first or second pod appears, Gabert says, you should only have to spray once for this particular pest.

“That’s their sole purpose in life: to perpetuate the species, sink into that pod, lay an egg and get those larvae feeding,” he says.

The thresholds for spraying are 25 to 40 in 10 sweeps, and in Gabert’s experience those numbers appear very accurate, he says.

“Hector Carcamo’s research indicated that you could sweep four times in a field — two pairs separated by 50 metres — to assess populations and be correct more than 90 per cent of the time,” Gabert says.

If farmers are seeing those levels, then it’s time to spray.

“We tell growers to spray between 10 and 20 per cent blue,” Gabert says.

Cultural control methods

While it hasn’t been widely adopted, Alberta Agriculture says trap cropping is the most promising cultural control method for managing the pest. Its web page dedicated to cabbage seedpod weevils says that by planting a trap border of early flowering field mustard (B. rapa) on the perimeter of a canola crop, the insects can be controlled by spraying that perimeter before they move into the main field.

The page also suggests later seeding of canola to help reduce weevil damage. But this method has to be balanced with the benefits of earlier seeding, which tends to produce higher yields in the absence of insect pests.

Parasitism

While the cabbage seedpod weevil is an introduced species and therefore has no natural enemies, there is growing evidence of parasitism.

“It does have some parasitoids that will attack it,” Tansey says.

The last work on that subject, done in the mid-2000s by Lloyd Dosdall, indicated numbers were relatively low, but the prevalence of parasitism was increasing.

“But the effect they’re having on populations is likely moderate at best,” Tansey says.

Fortunately, as mentioned, standard management practices appear to be effective at controlling the bugs.

“You really just need to scout,” Gabert says. “Especially if there’s a reasonable time lag between when the first field flowers and when the next few flower, it’s quite possible that you’ll drag most of them into the first field in the neighbourhood.”

The damage could be significant if high populations are left unchecked.

“Each of those larvae will eat three to five seeds, so if you have a lot of larvae, you’ll definitely lose yield,” Gabert says. “That’s why we’re comfortable with the threshold. If you’re over that threshold and you’re in an area that has significant numbers, they can definitely eat enough canola that you’ll have economic loss in your crop.”

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That was a key message from an April online seminar on insect control in canola organized by the University of Manitoba’s Faculty of Agricultural and Food Sciences.

The three panelists — Alejandro Costamagna, an entomology professor at the U of M; Hector Carcamo of Agriculture and Agri-Food Canada; and Keith Gabert of the Canola Council of Canada — talked primarily about flea beetles and lygus bugs, two of the most common canola pests in Western Canada.

Carcamo, an entomologist based at Lethbridge, said when lygus bugs are spotted in canola fields, they shouldn’t necessarily be viewed as a threat. In fact, the opposite could be true.

“Just because an insect is there, it does not mean that it’s a pest. In some cases, it can be a beneficial insect.”

Carcamo said low levels of insect feeding can stimulate crops like canola to produce better yields.

“We have to remember that insects and plants have had this very long history of a kind of love/hate relationship, where the insects have been attacking the plants and the plants have evolved defences and so on,” he said.

“We need to understand the biology of the insects and we need to appreciate that insect/plant interaction. At low levels, lygus bugs are not a pest. If you have a few lygus bugs attacking the crop at the early flower stage, the plants can actually become more robust, and they can actually over-yield and overcompensate.”

Carcamo said lygus bugs and flea beetles typically pose a threat only at certain times or stages of canola growth. For lygus bugs, that’s at the end of flowering, when there are plenty of canola pods with small, soft seeds inside.

“In general, that is the stage when lygus bugs are going to have the greatest risk and potentially affect the crop,” Carcamo said. “The key message is you have to get out there and sample at the correct stage.”

Gabert, a council agronomy specialist based at Innisfail, Alta., agreed.

“We can start finding lygus as soon as it warms up here on the Prairies. You’ll find the odd one creeping into your truck or in the ditch when you’re going to check the field at seeding time. But that’s not really an indication (you’re) going to have a problem in that field.”

Costamagna said the seedling stage is the most dangerous time for flea beetle damage.

“It’s a matter of timing. You’ll find (flea beetles) every year in every place, but they might not be (there) at the wrong time for your crop. They might completely miss the susceptible stage.”

In sufficient numbers, the insects can damage seedlings, but the plants quickly grow large enough to better withstand flea beetle pressure.

READ MORE: Prepping for the 2024 canola crop

“(Canola) is an amazing plant in the sense that within a couple of weeks it grows to an enormous size,” he said. “There could be lots of (flea beetles then), and they would be inconsequential.”

According to Costamagna, insecticidal seed treatments limit seedling damage from flea beetles in the critical three or four weeks after emergence.

Scouting key

The three experts agreed that scouting is essential for flea beetle and lygus bug management, particularly at times when crops are most vulnerable.

Noting the canola council has resources online for managing both pests, Gabert said he recommends “aggressive” scouting for flea beetles. By the time producers notice significant crop damage, it might be too late.

“Typically, when a grower is really concerned about flea beetles, it’s because he’s come and looked at the field seven days too late. (They are) looking at a field that already has 50 per cent plus damage. It’s had that damage for quite some time, and the grower is reacting to some pretty ugly-looking crop,” said Gabert.

“(It) is really critical to get out and scout when the crop is struggling,” he added, because flea beetle pressure can accelerate quickly in warm, dry conditions.

The experts also emphasized the need to use recommended thresholds when making spraying decisions.

Costamagna said thresholds should be heeded to avoid excessive insecticide use. It’s a waste of money if there’s no economic return to applications and it also reduces the risk of insecticide resistance.

Carcamo said agro-ecosystems in Western Canada typically contain many natural enemies of insect pests, which help curb pest populations in crops.

“For example, for lygus bugs we have determined that we have fairly high levels of parasitism by a very tiny wasp called peristenus. It can inflict reasonably good mortality on lygus bugs in some areas, so conserving these beneficial insects is very important,” he said.

“That is why it’s crucial that we understand these economic thresholds.”

Canola producers can learn more about beneficial insects through the Field Heroes program, said Gabert. He commended that initiative for promoting protection of beneficial insects.

Carcamo said several cultural control tools within the framework of integrated pest management can help farmers ward off flea beetle and lygus bug problems in canola. One of them is early seeding. Including more crops in a rotation and extending crop rotations are other helpful measures.

“The more crops that you can integrate into your rotation, (the more) you are going to limit the amount of food available for an insect pest,” he said, adding a forage crop can also be useful in boosting beneficial insect populations.

“Crops like alfalfa, they can harbour a huge number of insects … which can be excellent sources for (insect) predators like ladybird beetles.”

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“My advice (to farmers) is don’t turn your back on wheat midge, even if you are in a (low level) green zone on the provincial survey map,” says Tyler Wist, a field crop entomologist with Agriculture and Agri-Food Canada in Saskatoon.

“This is the biggest pest in wheat that we have in Western Canada and it’s not something that you want to take lightly.”

Wheat midge populations in Western Canada have been falling since the summer of 2021 when severe drought led to a significant decline in crop yields and a corresponding drop in the insect pest’s numbers.

That trend continued this past year. An insect pest survey conducted by the province of Saskatchewan showed significantly reduced populations of wheat midge in 2023 compared to 2022, although noteworthy hotspots were found north of Regina and some smaller dense populations were identified near Saskatoon, Kindersley and Lloydminster.

Alberta’s 2023 wheat midge survey results indicated a low population of wheat midge throughout the province, with the exception of a few fields in the Camrose and Edmonton regions.

Despite the declining numbers, Wist says producers should not be lulled into a false sense of security about the potential peril that wheat midge pose. Research has shown they can remain dormant in the soil for up to 13 years and can quickly become a concern again when an area receives normal or average rainfall levels.

“Thing can turn around pretty quickly,” says Wist. “They’ll come roaring back in a hurry if conditions are right.”

Full speed ahead

Now, he adds, is not the time for producers to take their foot off the gas when it comes to choosing midge-tolerant seed varieties.

“The best thing you can do is plant that midge-tolerant wheat because it’s there and it’s taking care of the wheat midge for you,” he says.

“You may be paying a bit more for it, but these days the midge-tolerant wheat is outyielding all of the midge non-tolerant wheat. The thing is, you never know when these insects are going to show up. We’re talking possibly 90 per cent yield loss in a field and that can happen in just a couple of days of females flying around in your field.”

Midge-tolerant wheat varieties were first developed by Agriculture and Agri-Food Canada following several major outbreaks of wheat midge on the Prairies in the 1990s. It’s estimated 32 per cent of all wheat now planted in Western Canada is midge-tolerant.

Such varieties have been available for the past 13 seasons. They contain a gene known as Sm1, which works by ramping up the production of phenolic acids in the seed when a midge starts to feed on it. The wheat midge doesn’t like the taste of those acids, stops feeding and subsequently starves to death.

Eileen Beaton, a crops extension specialist with the Saskatchewan government, says in a blog post several midge-tolerant wheat varieties are available for 2024, including varietal blends in CWRS, CPSR, CWSP, CWSWS, CWHWS, CHNR, CWES and durum wheat classes. A total of 36 varieties are registered and available for planting this season. More information on them is available online.

Another option to manage wheat midge risk is rotation to a non-host crop. Since spring wheat is the primary host for wheat midge, Beaton suggests producers consider planting a non-susceptible cereal crop such as oats or barley or a broadleaf crop such as canola or pulses, since midge adults are not strong fliers.

Difficult to detect

The wheat midge’s full name is the orange wheat blossom midge (Sitodiplosis mosellana). As its name suggests, it’s orange in appearance. It’s a member of the fly order (Diptera), although it closely resembles a mosquito because of its small size.

The adult wheat midge is not a threat to crops; rather, its larvae are. The adult female lays her eggs underneath a plant’s glumes, or leaf-like structures. Once those eggs hatch, the larvae tap into the wheat head’s developing kernel, causing the kernel to completely shrivel up and produce an unharvestable seed.

Part of what makes the wheat midge a formidable foe for farmers is that it can be difficult to detect until the damage has already been done.

“When it happens, you’re like, where did my seed go?” says Wist. “There’s no obvious exterior damage to the plant. You don’t see bites. You don’t see feeding damage.”

That’s why it’s important producers scout their wheat fields for the midge when it first emerges and is in its susceptible period, he says.

Wheat midge normally begin to emerge just before the Canada Day long weekend or soon after and emergence usually follows a significant rainfall. Growers, when scouting, should look for females crawling on heads in the plant’s canopy. The females generally lay their eggs at dusk or dawn when humidity is in the 60-70 per cent range and winds are calm. The economic threshold for yield is one female wheat midge for every five heads of wheat, which translates into a yield loss of about 15 per cent.

Three years ago, Wist teamed-up with SeCan, an independent seed retailer, as part of an initiative known as Midge Busters (#midgebusters on X). The project distributes pheromone traps to agronomists and farmers across Western Canada free of charge. Those traps are used to track the presence of wheat midge in farm fields and the data collected is then used to compare provincial midge forecasts with actual spring and summer emergence.

So, what causes some areas to become hotspots for wheat midge while other locations remain relatively untouched? Warm weather and precipitation are key factors, Wist says — but the truth is, much remains unknown about the pest and its habits.

“The pheromone trapping is something that I’m trying to continuously expand because more data is always better,” he says. “We can fill in those gaps in those areas to help determine what’s truly going on in some regions … like why is one region booming and another one isn’t?”

Diminished insecticide options

For farmers who choose non-midge tolerant wheat varieties, the number of insecticide options has recently diminished. Insecticides containing the active ingredient chlorpyrifos, such as Lorsban 4E, can no longer be used as they have been deregistered by Health Canada.

Beaton says some alternative insecticides such as Cygon and Lagon, which contain the active ingredient dimethoate, are available for use.

Wist says producers who use those products need to be extremely careful to apply them at the right time. If they are sprayed too late they will have little impact on the adult wheat midge or the eggs the females lay.

Those products can also cause harm to parasitic wasps known as Macroglenes penetrans, which are a natural enemy of wheat midge and help to keep their numbers low.

“It’s a really good predator of the wheat midge,” Wist says. “It acts by killing those over-wintering cocoons of the wheat midge. Not spraying for wheat midge too late helps to preserve populations of those parasitoids.”

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That was one message delivered at last month’s Canola Week annual meetings in Calgary, which brought together canola industry leaders from across North America.

Meghan Vankosky, a field crop entomologist with Agriculture and Agri-Food Canada based in Saskatoon, spoke during a crop update panel.

She said the number of areas in the Prairies with higher grasshopper populations has been increasing in recent years. That was especially true in 2023 in southern regions of Alberta and Saskatchewan, and to a less extent parts of Manitoba.

Head start

Vankosky, who is also co-chair of the Prairie Pest Monitoring Network, said grasshoppers got off to a “great head start” last spring because of the hot, dry conditions that blanketed large sections of the Prairie provinces.

“We usually start going out to selected sites in Saskatchewan during that first week of May with our summer students because we want to get zeros. We want to know there are no grasshopper nymphs yet,” she said.

“Well, there were already grasshopper nymphs the first week of May. We had grasshopper development almost two weeks ahead of normal in 2023 because of that hot start in May.

“That meant that by June 15, we had adult pest grasshoppers on the Prairies. That has not happened in over 35 years. I work with people who have been working on grasshoppers their entire careers… and they’ve never seen adult grasshoppers in June. That’s not good.”

The situation was so bad in parts of southwestern Saskatchewan that some rural municipalities were “disaster zones” where grasshopper damage combined with the effects of drought and losses from ground squirrels.

Though grasshoppers don’t normally prefer canola, they make an exception when conditions are dry and they are desperate for food, Vankosky said.

The grasshopper situation in 2024 will largely depend on weather, she said. If it stays warm and dry again, as it has in the past few years, “2024 is looking to be unfortunately even worse than 2023 in terms of grasshoppers.”

Be ready

She advises producers to scout early and often.

“Grasshoppers are easiest to kill when they’re small because they can’t get away from the insecticides and it takes less of the insecticide to kill. You can treat the ditches or the field edges before they move into the field and you then have to spray the whole field.”

Vankosky also advised farmers to check provincial and regional pest maps when they are released and watch the web for the latest information provided by provincial officials and the Prairie Pest Monitoring Network.

Taking note

Dan Johnson, a professor of environmental science at the University of Lethbridge and a former specialist with AAFC, spoke about what he referred to as “the re-emerging grasshopper problem” during a panel about insect management tools.

He said it’s important to note what kinds of grasshoppers are present to determine how much damage they could potentially cause and how best to limit it.

There are about 80 species of grasshoppers in Western Canada, but only a handful are considered crop pests.

The two-striped grasshopper is a notorious “gobbler” of most crops, including canola. It feeds on canola pods, causing serious damage, and can even clip them right off a plant. It has two pale stripes that extend from its eyes to the tips of its forewings and solid black stripes on its hind legs.

Johnson said the two-striped variety can be difficult to identify because they change colour during the season. They are normally tan after hatching before becoming green, purple, orange or yellow soon after.

The Packard’s grasshopper and Bruner’s spur-throated grasshopper are two other troublesome species in canola and other broadleaf crops. The young Packard’s is green with black scattered dots that resemble pepper, and the adult version is grey to dark yellow with two light-coloured stripes behind the eyes with grey forewings.

The Bruner’s grasshopper is pale to dark brown with a hind tibia that is usually pink or red. It is more common in foothills and northern regions, although it’s also an issue in a few southern areas such as the Cypress Hills region in Alberta.

Clear-winged grasshoppers aren’t much of a threat to canola since they prefer to feed on grass and cereal crops, Johnson said. They are yellowish or brownish with clear wings adorned with dark patches.

Any grasshopper with hind wings that are highly visible in flight (red, yellow, orange or black) or that sing or clack, are not pests.

Johnson noted thresholds don’t really matter when it comes to grasshoppers.

“This is not an insect that thresholds apply to very well. Look for damage,” he said.

Fewer tools available

He also told growers that fewer tools will be available to fight grasshoppers this season.

Health Canada’s Pest Management Regulatory Agency determined last year that lambda-cyhalothrin products such as Matador and Silencer will not be available for use on crops destined for livestock feed, which effectively means they can no longer be used for any grain, oilseed or pulse crop grown in Western Canada.

There are some biological controls, which Johnson said offer “some pretty good control” but they may take time to work.

Weather data from the 1950s to the present shows average temperatures trending upward, which doesn’t bode well for future grasshopper populations, said Johnson.

“We might have to get used to grasshoppers because they benefit from that (rise in temperatures).”

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A: In the spring, the threat of insects may seem far off, but there are steps you can take at seeding time to reduce the risk of insect damage. Proactive measures are powerful tools to protect yield and reduce the amount of foliar insecticides applied in crop, saving time and money while preserving beneficial insect populations.

The first step of a well-rounded approach to insect management is to be aware of past insect issues and anticipate what problems could arise going forward. 

Scouting or working with a trusted agronomist allow for insects to be correctly identified in season. While it is too late to act proactively once an issue is identified, having the information will be helpful to future seasons. 

Next, ask yourself the following questions. If insect damage has been identified in the past, what were some of the factors that contributed to high levels of damage? Could changes to crop rotation, variety selection, seeding rate and seed treatments mitigate the issue? 

Crop rotation provides many agronomic benefits and insect management is no exception. When the same crop is grown on the same field for multiple seasons in a row, populations of crop pest insects are allowed to build up with a constant availability of food and habitat. Growing non-host crops breaks this cycle. 

In addition to crop rotation, varietal selection is a highly effective tool against insect damage. There are wheat varieties that provide protection from wheat midge and wheat stem sawfly. Corn hybrids are available with a trait to protect against corn borer. If these insects are known issues on your farm, selecting a resistant variety is an excellent option. 

Once you’re ready to select a seeding rate, insect management should be taken into consideration along with other factors. For example, thinner plant stands are exacerbated by insect damage, leaving fewer healthy plants. 

Damage from flea beetles and cutworms, which can remove entire plants, becomes more serious when there are fewer plants to begin with. For pests like wheat midge, having a full and uniform plant stand reduces the amount of time the crop is in a vulnerable stage and makes timing a foliar insecticide application simpler, if needed. 

Lastly, choosing an insecticidal seed treatment provides protection from early-season insect pressure. Base canola seed treatments provide broad-spectrum insect control with add-on treatments available for enhanced activity on flea beetles and/or cutworms. For some insects like pea leaf weevil, insecticidal seed treatments are the only viable chemical control option — foliar insecticides are ineffective. 

An integrated, proactive approach to insect management is often much more effective than a reactive strategy, but it does require planning ahead. Taking a few minutes before seeding gets too hectic to plan your insect management strategy for the coming season will pay dividends.

Stacie Yaremko, PAg, CCA, is the manager of agronomic solutions in the Peace Region of northern Alberta for Nutrien Ag Solutions.

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