By Angie Peltier UMN Extension crops educator, Fei Yang, UMN Extension corn entomologist and Robert Koch, UMN Extension soybean entomologist
February 25, 2026’s Strategic Farming: Let’s Talk Crops session discussed the status of the many pests that can limit Minnesota’s corn and soybean yield potential, how these pests have been able to overcome many of our most effective management techniques and how best to manage in 2026. This webinar series runs through March and registrations are still being accepted: https://extension.umn.edu/courses-and-events/strategic-farming. To watch this episode visit: http://z.umn.edu/StrategicFarmingRecordings.
Soybean aphids are the most yield-limiting insect pest of Minnesota soybeans, capable of causing up to 40% yield loss. Since its initial introduction in the early 2000’s into upper Midwest, soybean aphid infestations in states east of Minnesota have declined over time, but infestations in Minnesota have remained problematic. Management of soybean aphid has primarily relied upon insecticides and until approximately 2014, soybean aphids were well controlled with the pyrethroid class of insecticides. Starting in 2014, researchers and crop producers and consultants alike began to note a sharp decline in aphid mortality to pyrethroid insecticides; UMN researchers were able to confirm resistance through bioassays with field collected populations.
Robert Koch’s lab continues to run soybean aphid insecticide efficacy field trials to both continue to monitor insecticide resistance and test new and emerging active ingredients. One late-planted (July 10) trial at Rosemount, MN in 2025 tested various insecticides applied at 20 gallons per acre and 30 psi to soybeans that had just reached the beginning pod (R3) growth stage. This trial was sprayed when the soybean aphid population density was 60 aphids/plant, long before the aphid population had reached the treatment threshold of more than 80% of plants infested and an average and growing population of 250 aphids/plant.
February 25, 2026’s Strategic Farming: Let’s Talk Crops session discussed the status of the many pests that can limit Minnesota’s corn and soybean yield potential, how these pests have been able to overcome many of our most effective management techniques and how best to manage in 2026. This webinar series runs through March and registrations are still being accepted: https://extension.umn.edu/courses-and-events/strategic-farming. To watch this episode visit: http://z.umn.edu/StrategicFarmingRecordings.
The status of soybean aphid resistance
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| Soybean aphid. Photo: Bob Koch |
Robert Koch’s lab continues to run soybean aphid insecticide efficacy field trials to both continue to monitor insecticide resistance and test new and emerging active ingredients. One late-planted (July 10) trial at Rosemount, MN in 2025 tested various insecticides applied at 20 gallons per acre and 30 psi to soybeans that had just reached the beginning pod (R3) growth stage. This trial was sprayed when the soybean aphid population density was 60 aphids/plant, long before the aphid population had reached the treatment threshold of more than 80% of plants infested and an average and growing population of 250 aphids/plant.
One week after treatment, all of the newer insecticides that were applied resulted in very high levels of control and soybean aphid population densities increased to more than 100/plant in plots that were either not treated or treated with Warrior II, an insecticide in the pyrethroid class. However, 2 and 3 weeks after treatment, the aphid populations were greater than 300 and 400 aphids per plant, respectively, in the plots treated with Warrior II, while the populations decreased naturally in the untreated plots, likely due to natural enemies. This work revealed that pyrethroid resistance is still a trait prevalent in some Minnesota soybean aphid populations. Making an application of a broad spectrum insecticide such as Warrior II to which aphids are resistant can have pitfalls above and beyond the cost of the application, including the growth of the soybean aphid population density -that would have otherwise naturally fallen- to surpass the economic threshold. Using an ineffective (due to resistance), broad-spectrum insecticide may have resulted in the loss of natural enemies of aphids in those plots that may have been keeping the population in check before the insecticide application.
Particularly striking was the drop in aphid populations in the untreated plots as their populations began to naturally decline. This data point was the perfect illustration of why infestations should be assessed on a regular basis to determine if they are increasing or decreasing, and it highlights that not all infestations below the threshold will continue to grow to damaging levels. There are multiple biological factors that work against aphid populations and can cause natural decreases. The treatment threshold is based on many years of data collection and tends to be conservative. At a density of 250 aphids per plant, loss to the crop’s yield potential has not yet taken place. However, if population densities continue to grow unabated, yield potential will be lost if left untreated. Use of the economic threshold for determining when to apply insecticides is even more important given both the limited effective insecticide tools in our toolbox and the current farm economy.
Of additional concern is the inconsistent control observed with insecticide premix products containing both pyrethroids (generally no longer effective) and neonicotinoid active ingredients. In the 2025 insecticide study in Rosemount, Koch’s team found that while still quite effective, when aphid populations were counted 2 weeks after treatment with Endigo ZXC (a pyrethroid & neonicotinoid mixture), control was not as good as mixtures that contained one of the newer classes of chemistries labeled for soybean aphid. This is in agreement with a study from 2024 testing a different pyrethroid/neonicotinoid mixture (Leverage 360); this trial showed that aphid populations 15 days after treatment were significantly higher than the untreated plots.
Entomologists generally prefer that folks rotate individual insecticide groups to slow the speed that resistance evolves in pest populations. Seed treatment insecticides belong to the neonicotinoid class of insecticides. Unless one is treating soybeans for aphids and there are other economically-important pests that are also at treatment threshold, there is really no reason to use a premix product containing one of the newer, still effective, more aphid-selective chemistries combined with a pyrethroid. Routine use of these mixtures which contain an insecticide to which the pest has already developed resistance can create selection pressure for resistance to the other insecticide component of the product.
Here is an updated publication that provides recommendations about the Management of Pyrethroid-resistant Soybean Aphids.
Infested plants can wilt and die as SGM interrupts water flow within the plant. SGM also causes stem breakage as infested stems become brittle and lodge easily as leaves and pods are added to the plant.
Since it was first discovered in Rock County, Minnesota in 2018, SGM has continued to expand its range in soybeans throughout counties west and south of Stearns County. In 2024 and 2025, additional findings have included infestations in sweet clover or soybean in Hennepin, Chisago, Dakota and Ramsey Counties. In addition to soybean and sweet clover, SGM can also colonize alfalfa, dry bean and other legumes.
Managing SGM is difficult, as insecticides, whether they are applied at planting time in-furrow or as seed treatments, or as foliar-applied products have generally shown little efficacy. While research from Nebraska has shown that burying the base of the plant by hilling soil onto the lower stem tissue before eggs are laid can provide very effective plant protection, it is difficult to consider this a practical or easily adopted management technique given modern soybean production techniques.
Current research in the Koch lab on SGM management has focused on screening soybean breeding lines for resistance and biological control. Among soybean lines challenged directly with SGM, one soybean line has shown promise with larval populations one-third those on lines known to be SGM-susceptible. Pitfall traps (essentially a deli container containing antifreeze covered with a water-resistant plate) were set up in SGM infested fields to capture and quantify other insects that might act as SGM predators. A ground-dwelling beetle (Pterostichus melanarius) was the insect that fell into the pitfall trap most frequently. Feeding studies in the lab in which a known quantity of SGM larvae were fed to this predator determined that it not only ate SGM, but was capable of consuming an average of 40 per hour! Field-collected beetles were dissected and their guts were tested for the presence of SGM DNA, an indicator that feeding on SGM larvae occurs naturally in farm fields and isn’t simply a lab-related phenomenon. This research revealed that not only was this predatory beetle consuming SGM in the field, the percentage of beetles that had consumed SGM tended to increase as SGM density in the field increased. In addition to predatory ground beetles, two new parasitic wasps have been discovered colonizing Minnesota SGM, Synopeas maximum (a species new to science) and S. ruficoxam (previously found in Canada). Studies in which molecular techniques allowed researchers to detect parasitic wasp DNA from field collected SGM found that up to 60% of larvae were parasitized.
For additional updates on soybean gall midge, on March 19, from 9 to 11 am, consider attending the online Soybean Gall Midge Research Update.
Particularly striking was the drop in aphid populations in the untreated plots as their populations began to naturally decline. This data point was the perfect illustration of why infestations should be assessed on a regular basis to determine if they are increasing or decreasing, and it highlights that not all infestations below the threshold will continue to grow to damaging levels. There are multiple biological factors that work against aphid populations and can cause natural decreases. The treatment threshold is based on many years of data collection and tends to be conservative. At a density of 250 aphids per plant, loss to the crop’s yield potential has not yet taken place. However, if population densities continue to grow unabated, yield potential will be lost if left untreated. Use of the economic threshold for determining when to apply insecticides is even more important given both the limited effective insecticide tools in our toolbox and the current farm economy.
Of additional concern is the inconsistent control observed with insecticide premix products containing both pyrethroids (generally no longer effective) and neonicotinoid active ingredients. In the 2025 insecticide study in Rosemount, Koch’s team found that while still quite effective, when aphid populations were counted 2 weeks after treatment with Endigo ZXC (a pyrethroid & neonicotinoid mixture), control was not as good as mixtures that contained one of the newer classes of chemistries labeled for soybean aphid. This is in agreement with a study from 2024 testing a different pyrethroid/neonicotinoid mixture (Leverage 360); this trial showed that aphid populations 15 days after treatment were significantly higher than the untreated plots.
Entomologists generally prefer that folks rotate individual insecticide groups to slow the speed that resistance evolves in pest populations. Seed treatment insecticides belong to the neonicotinoid class of insecticides. Unless one is treating soybeans for aphids and there are other economically-important pests that are also at treatment threshold, there is really no reason to use a premix product containing one of the newer, still effective, more aphid-selective chemistries combined with a pyrethroid. Routine use of these mixtures which contain an insecticide to which the pest has already developed resistance can create selection pressure for resistance to the other insecticide component of the product.
Here is an updated publication that provides recommendations about the Management of Pyrethroid-resistant Soybean Aphids.
Soybean gall midge update
Never having been documented in the US (or anywhere else) before, soybean gall midge infestation causing very visible crop losses on field edges in some soybean fields brought this pest to the forefront for farmers and researchers alike in 2018. The adult soybean gall midge (SGM) lays eggs in the expansion cracks that form on stems near the base of the plant. There, eggs hatch and white and orange maggots begin to feed underneath the outer layer of stem tissue. Once larvae have progressed through three developmental stages, they exit the plant and drop to the soil where they form a cocoon to pupate.Infested plants can wilt and die as SGM interrupts water flow within the plant. SGM also causes stem breakage as infested stems become brittle and lodge easily as leaves and pods are added to the plant.
Since it was first discovered in Rock County, Minnesota in 2018, SGM has continued to expand its range in soybeans throughout counties west and south of Stearns County. In 2024 and 2025, additional findings have included infestations in sweet clover or soybean in Hennepin, Chisago, Dakota and Ramsey Counties. In addition to soybean and sweet clover, SGM can also colonize alfalfa, dry bean and other legumes.
Managing SGM is difficult, as insecticides, whether they are applied at planting time in-furrow or as seed treatments, or as foliar-applied products have generally shown little efficacy. While research from Nebraska has shown that burying the base of the plant by hilling soil onto the lower stem tissue before eggs are laid can provide very effective plant protection, it is difficult to consider this a practical or easily adopted management technique given modern soybean production techniques.
Current research in the Koch lab on SGM management has focused on screening soybean breeding lines for resistance and biological control. Among soybean lines challenged directly with SGM, one soybean line has shown promise with larval populations one-third those on lines known to be SGM-susceptible. Pitfall traps (essentially a deli container containing antifreeze covered with a water-resistant plate) were set up in SGM infested fields to capture and quantify other insects that might act as SGM predators. A ground-dwelling beetle (Pterostichus melanarius) was the insect that fell into the pitfall trap most frequently. Feeding studies in the lab in which a known quantity of SGM larvae were fed to this predator determined that it not only ate SGM, but was capable of consuming an average of 40 per hour! Field-collected beetles were dissected and their guts were tested for the presence of SGM DNA, an indicator that feeding on SGM larvae occurs naturally in farm fields and isn’t simply a lab-related phenomenon. This research revealed that not only was this predatory beetle consuming SGM in the field, the percentage of beetles that had consumed SGM tended to increase as SGM density in the field increased. In addition to predatory ground beetles, two new parasitic wasps have been discovered colonizing Minnesota SGM, Synopeas maximum (a species new to science) and S. ruficoxam (previously found in Canada). Studies in which molecular techniques allowed researchers to detect parasitic wasp DNA from field collected SGM found that up to 60% of larvae were parasitized.
For additional updates on soybean gall midge, on March 19, from 9 to 11 am, consider attending the online Soybean Gall Midge Research Update.
European corn borer
ECB life cycle
European corn borer (ECB) moths find a mate and females lay their fertilized eggs on the underside of corn leaves. After eggs hatch into larvae, larvae feed on leaf tissue, often inside of the whorl, creating a unique pattern of feeding injury: as larvae feed on multiple layers of a corn leaf wrapped around itself within a whorl, multiple holes can be observed after ECB feeding, arranged in parallel across the width of leaves (Figure 1). After several molts, larvae are large enough to chew their way into the stalk, ear shank or developing cob, where they finish out their remaining larval stages. While most larvae crawl out of the plant to pupate, some spend the winter in corn residue (stalk, ear shank or cob tissue) with the majority 5th instar larvae spending the winter in the soil. Once ECB has bored into the stalk, it is beyond the reach of foliar insecticides.
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| Figure 1a. Injury symptoms caused by European corn borer include parallel
‘shot-holing’ of leaf tissue due to feeding on leaves still in the whorl and bore holes in stalks. Photos: Yang Lab, UMN Extension. |
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| Figure 1b. Stalk lodging damage caused by European corn borer. Photo: Yang Lab, UMN Extension |
ECB strains in Minnesota
A pest that can easily overwinter in Minesota, ECB has two different lifestyles largely based on temperature; univoltine strains tend to occur in northern Minnesota and have a single generation each growing season, while multivoltine strains tend to occur in the southern 2/3 of Minnesota and have multiple generations in a single growing season. Complicating the period of time in which producers of conventional or non-Bt corn hybrids and their advisors need to scout and carefully time an insecticide-based management, are those areas of the state in the transition zone in which both univoltine and multivoltine strains overlap.
Causes of feeding injury are easy to confuse
Confusing ECB injury with injury caused by corn rootworm or common stalk borer is not uncommon. Lodging caused by rootworm injury is of the whole plant, starting at the roots. Symptoms of feeding injury on roots, such as pruned or discolored brace roots are also a good indicator that ECB is not to blame (Figure 2). Symptoms of ECB feeding injury include bore holes (often accompanied by ECB waste called frass) that can occur anywhere on the stalk, in ear shanks or in cobs. Injury caused by common stalk borer can resemble ECB damage, including parallel rows of holes in leaves and bore holes with tunneling in the stalk (Figure 3).
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| Figure 2. Root lodging resulting from corn rootworm feeding injury on corn roots. Photo: Yang Lab, UMN Extension |
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| Figure 3. Shot-holing, bore holes accompanied by insect frass and internal stalk injury caused by common stalk borer (pictured) can be easily confused with symptoms caused by European corn borer. Photos: Yang Lab, UMN Extension |
Because they initially feed on grassy plants on field edges before moving into corn fields to feed, common stalk borer injury tends to be most prevalent in the first couple of rows that border grassy field borders. The Bt traits that provide protection against ECB are not effective against common stalk borer and so if you have a field of Bt corn with considerable ECB-like damage, but just on the field edge, you could be dealing with a common stalk borer infestation.
ECB Bt corn traits
The tremendous time required to scout for ECB and the narrow window in which to treat (leading to ineffective control), historically resulted in considerable ECB-related yield loss in Minnesota. ECB-related yield loss also meant that this pest was the first target for Bt trait development in hybrid corn. Bt, an abbreviation for Bacillus thuringiensis, is a soil-borne, spore-producing bacterium that produces insecticidal proteins. When ingested by sensitive insect pests, these proteins bind to receptors in the insect’s midgut, create pores and ultimately cause the pest to die from a bacterial infection. The first Bt corn hybrids had the genes involved in the production of an ECB-specific Bt protein genetically engineered into them so that Bt proteins were expressed in all plant tissue.
There are now multiple, Bt traits ‘stacked’ into a single hybrid to slow the speed that ECB evolves to overcome this management technique. There are two ‘families’ of Bt proteins for ECB: Cry1, which includes the Cry1Ab, Cry1F and Cry1A.105 proteins and Cry 2, or the Cry2Ab protein. Entomologists from universities, companies, and federal regulators charged with approving transgenic traits such as Bt, worked to develop a series of best management practices to slow the speed of resistance (to one or more Bt traits) development in the field. One of these management practices was the adoption of ‘refuges’, or plants that do not express Bt proteins, so that not every ECB larva feeds on a plant expressing Bt proteins – some feed on nonBt plants. As so few ECB can survive Bt plants, and a Bt-resistant adult is much more likely to encounter and mate with abundant susceptible adults from refuge plants, producing heterozygous offspring. When resistance is conferred by a recessive gene, these heterozygous offspring will be killed by the Bt plants, thereby slowing resistance development at the population level. Since they were first deployed in 1996, ECB Bt corn hybrids, stacked traits and refuge strategy combined have provided excellent control across the Corn Belt. However, field-evolved resistance to Cry1F, Cry1Ab and Cry1A.105 has been recently reported in Nova Scotia (2018), Manitoba and several other provinces in Canada (2019-2023) and more recently with resistance to multiple traits (Cry1Ab, Cry1A.105 and Cry2Ab2) observed in Connecticut in 2023-2024.
There are now multiple, Bt traits ‘stacked’ into a single hybrid to slow the speed that ECB evolves to overcome this management technique. There are two ‘families’ of Bt proteins for ECB: Cry1, which includes the Cry1Ab, Cry1F and Cry1A.105 proteins and Cry 2, or the Cry2Ab protein. Entomologists from universities, companies, and federal regulators charged with approving transgenic traits such as Bt, worked to develop a series of best management practices to slow the speed of resistance (to one or more Bt traits) development in the field. One of these management practices was the adoption of ‘refuges’, or plants that do not express Bt proteins, so that not every ECB larva feeds on a plant expressing Bt proteins – some feed on nonBt plants. As so few ECB can survive Bt plants, and a Bt-resistant adult is much more likely to encounter and mate with abundant susceptible adults from refuge plants, producing heterozygous offspring. When resistance is conferred by a recessive gene, these heterozygous offspring will be killed by the Bt plants, thereby slowing resistance development at the population level. Since they were first deployed in 1996, ECB Bt corn hybrids, stacked traits and refuge strategy combined have provided excellent control across the Corn Belt. However, field-evolved resistance to Cry1F, Cry1Ab and Cry1A.105 has been recently reported in Nova Scotia (2018), Manitoba and several other provinces in Canada (2019-2023) and more recently with resistance to multiple traits (Cry1Ab, Cry1A.105 and Cry2Ab2) observed in Connecticut in 2023-2024.
Status of Bt-resistance alleles in Minnesota
Of worry to Yang and other Minnesota entomologists is the fact that there is tremendous selection pressure being exerted on the ECB population to evolve Bt resistance as more than 90% of US corn acres have Bt traits and long-term use of any single form of management increases this selection pressure. Of additional concern is that once Bt resistance develops in ECB, moths are highly mobile and capable of flying long distances or moving on weather systems, accelerating the resistance dispersal and development.
Despite the fact that the widespread adoption of ECB Bt corn in Minnesota has led to an overall suppression of ECB population densities, there are still large ‘hotspot’ ECB populations that occur in nonBt fields. ECB larvae from nonBt fields in Minnesota, North Dakota and Wisconsin were collected, pupae reared and the resulting adults mated to one another. Those progeny were also mated and the resulting larvae were fed a corn-agar based diet infused with Bt proteins to determine larval survival and therefore the frequency of resistance alleles to individual Bt traits. Among the 84 families tested in this way against the Cry1F, Cry1Ab and Cry1A.105, none survived, meaning that the frequency of Bt resistance to the Cry1 proteins is low. Among the 84 families tested against the Cry2Ab2 Bt protein however, 14 had survivors, meaning that the frequency of Bt resistance to the Cry2Ab2 Bt protein is high. Even when exposed to the highest concentration of the Cry2Ab2 protein in the feeding assay, 65-100% individuals of these resistant populations could survive at 5400 ng/cm2.
Greenhouse-based studies of hybrids expressing single and stacked ECB Bt traits were also tested to make sure that this resistance is biologically relevant. ECB populations expressing either Bt susceptible alleles, Bt resistance alleles or one of each (called heterozygous, the result of a Bt sensitive individual being mated with a Bt resistant individual). Between 80 and 95% of nonBt plants became infested with ECB, with similar levels of infestation among sensitive, resistant and heterozygous populations. While ~10% of corn plants expressing a low concentration of the Cry2Ab2 protein were colonized by the Bt-sensitive population, they were unable to colonize corn plants expressing a higher concentration of the protein. However, 70 to 80% of the corn plants expressing both the high and low concentrations of Cry2Ab2 were colonized by the Cry2Ab2-resistant populations of ECB. Heterozygous ECB populations were able to colonize approximately 40% and 20% of plants expressing the low and high concentrations of Cry2Ab2, respectively, suggesting that the gene that confers Bt resistance is not a recessive trait.
Cross-resistance is a phenomenon in which resistance to one pesticide or Bt trait confers resistance to another pesticide or Bt trait because both share a similar resistance mechanism in the pest. One small bit of positive news on the Bt-resistance front is that no cross resistance to any Cry1 Bt proteins has been observed in the tested Cry2Ab2 resistant ECB populations. This means that while there is a high frequency of Bt resistance to the Cry2Ab2 protein, the ECB Cry1 proteins are still effective.
Bt trait packages available to Minnesota corn producers such as VT Double Pro, Trecepta, PowerCore, Vorceed, and SmartStax, all contain both Cry1 and Cry2 ECB Bt proteins, and so are likely to still be effective in the near-term. However, there is now even more selection pressure being exerted on the ECB population to resist the Cry1 proteins. ECB Bt resistance in Canada is the opposite of the resistance in Minnesota, meaning that the Cry2Ab2 trait is effective in Canada, but two of the Cry1 proteins aren’t. With ECB moths capable of long-distance travel, the worry is that at some point the Cry1 resistant populations makes their way to Minnesota or Wisconsin and mates with our Cry2Ab2 resistant populations effectively spelling the end of effective Bt management of ECB.
Thanks to the Minnesota Soybean Research & Promotion Council and the Minnesota Corn Research & Promotion Council for their generous support of this program!
Despite the fact that the widespread adoption of ECB Bt corn in Minnesota has led to an overall suppression of ECB population densities, there are still large ‘hotspot’ ECB populations that occur in nonBt fields. ECB larvae from nonBt fields in Minnesota, North Dakota and Wisconsin were collected, pupae reared and the resulting adults mated to one another. Those progeny were also mated and the resulting larvae were fed a corn-agar based diet infused with Bt proteins to determine larval survival and therefore the frequency of resistance alleles to individual Bt traits. Among the 84 families tested in this way against the Cry1F, Cry1Ab and Cry1A.105, none survived, meaning that the frequency of Bt resistance to the Cry1 proteins is low. Among the 84 families tested against the Cry2Ab2 Bt protein however, 14 had survivors, meaning that the frequency of Bt resistance to the Cry2Ab2 Bt protein is high. Even when exposed to the highest concentration of the Cry2Ab2 protein in the feeding assay, 65-100% individuals of these resistant populations could survive at 5400 ng/cm2.
Greenhouse-based studies of hybrids expressing single and stacked ECB Bt traits were also tested to make sure that this resistance is biologically relevant. ECB populations expressing either Bt susceptible alleles, Bt resistance alleles or one of each (called heterozygous, the result of a Bt sensitive individual being mated with a Bt resistant individual). Between 80 and 95% of nonBt plants became infested with ECB, with similar levels of infestation among sensitive, resistant and heterozygous populations. While ~10% of corn plants expressing a low concentration of the Cry2Ab2 protein were colonized by the Bt-sensitive population, they were unable to colonize corn plants expressing a higher concentration of the protein. However, 70 to 80% of the corn plants expressing both the high and low concentrations of Cry2Ab2 were colonized by the Cry2Ab2-resistant populations of ECB. Heterozygous ECB populations were able to colonize approximately 40% and 20% of plants expressing the low and high concentrations of Cry2Ab2, respectively, suggesting that the gene that confers Bt resistance is not a recessive trait.
Cross-resistance is a phenomenon in which resistance to one pesticide or Bt trait confers resistance to another pesticide or Bt trait because both share a similar resistance mechanism in the pest. One small bit of positive news on the Bt-resistance front is that no cross resistance to any Cry1 Bt proteins has been observed in the tested Cry2Ab2 resistant ECB populations. This means that while there is a high frequency of Bt resistance to the Cry2Ab2 protein, the ECB Cry1 proteins are still effective.
Bt trait packages available to Minnesota corn producers such as VT Double Pro, Trecepta, PowerCore, Vorceed, and SmartStax, all contain both Cry1 and Cry2 ECB Bt proteins, and so are likely to still be effective in the near-term. However, there is now even more selection pressure being exerted on the ECB population to resist the Cry1 proteins. ECB Bt resistance in Canada is the opposite of the resistance in Minnesota, meaning that the Cry2Ab2 trait is effective in Canada, but two of the Cry1 proteins aren’t. With ECB moths capable of long-distance travel, the worry is that at some point the Cry1 resistant populations makes their way to Minnesota or Wisconsin and mates with our Cry2Ab2 resistant populations effectively spelling the end of effective Bt management of ECB.
Audience questions
Koch and Yang fielded numerous audience questions including: is Pyganic, an insecticide labeled for organic aphid management, effective against soybean aphid?; can SGM survive the Minnesota winter, and if so how low of a temperature is needed to kill it?; are there any chlorpyrifos products with a Minnesota label for soybean aphid control in 2026?; should Minnesota soybean growers worry about SGM?; How can one best time when to hill plants for SGM management?; from where did SGM originate (is it invasive or native)?; how far can ECB migrate?; how can we manage ECB once Bt traits are no longer effective?; how do cover crops impact insect pest pressure?Thanks to the Minnesota Soybean Research & Promotion Council and the Minnesota Corn Research & Promotion Council for their generous support of this program!
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