Scientists discovered that a major corn pest called the European corn borer has developed resistance to a genetically modified corn defense in Canada. Researchers studied how this resistant pest population survives and reproduces compared to non-resistant populations. They found that the resistant bugs actually reproduce faster and live longer than normal bugs, which means the resistant population could spread quickly through corn fields. This is concerning for farmers because it suggests the pest’s resistance won’t naturally disappear on its own, and urgent action is needed to prevent widespread resistance.

The Quick Take

  • What they studied: How well corn borers with resistance to genetically modified corn can survive and reproduce compared to regular corn borers
  • Who participated: Laboratory populations of European corn borers, including resistant bugs found in Nova Scotia in 2018 and normal susceptible bugs, studied under controlled conditions
  • Key finding: Resistant corn borers actually had 2.4 times more babies, lived 2 days longer, and their population could grow 1.6 times faster than normal corn borers
  • What it means for you: If you grow corn or care about food production, this matters because pest resistance could spread quickly. However, this is a specialized agricultural concern that farmers and agricultural experts need to address through pest management strategies

The Research Details

Researchers compared three groups of corn borers in laboratory conditions: bugs that were resistant to Cry1Fa (a natural pesticide used in genetically modified corn), bugs that were not resistant, and bugs that carried one copy of the resistance gene and one copy of the normal gene. They measured how long the bugs lived, how many babies each female produced, and how long it took for eggs to develop into adults. This allowed them to understand whether resistance would spread quickly through wild populations.

The scientists used two different testing methods to confirm resistance: they fed bugs a special diet containing the pesticide, and they also tested the bugs’ body tissues directly. Both methods confirmed that the resistance trait follows a recessive inheritance pattern, meaning a bug needs to inherit the resistance gene from both parents to show resistance.

Understanding how resistant pests survive and reproduce is crucial for predicting whether resistance will spread in nature. If resistant bugs have lower survival rates or fewer babies, resistance might stay limited. But if they thrive just as well or better than normal bugs, resistance will likely spread rapidly through the pest population, making the genetically modified corn less effective as a pest control tool.

This study was published in a peer-reviewed scientific journal focused on agricultural economics and entomology. The research used controlled laboratory conditions, which allows precise measurement of traits but may not perfectly reflect what happens in real corn fields. The study examined actual field-evolved resistance rather than artificially created resistance, making the findings more relevant to real-world farming situations.

What the Results Show

The resistant corn borers showed surprising advantages over normal borers. Female resistant bugs produced an average of 2.4 times more eggs than susceptible females, which is a major difference. Adult resistant bugs lived about 2 days longer on average than susceptible bugs. However, resistant bugs took about 6.5 days longer to develop from egg to adult.

When researchers calculated the overall population growth rate—combining reproduction, lifespan, and development time—they found that resistant populations could grow 1.6 times faster than susceptible populations. This means that if resistant bugs are present in a corn field, their numbers could increase much more rapidly than normal bug populations.

The resistance trait itself was found to be recessive, meaning a bug must inherit the resistance gene from both parents to actually resist the pesticide. This is important because it affects how quickly resistance spreads through a population.

The longer development time for resistant bugs (6.5 days more) was the only characteristic where they performed worse than normal bugs. This could potentially slow their population growth slightly, but the massive increase in reproduction more than compensates for this disadvantage. The longer adult lifespan also helps resistant populations because the bugs have more time to reproduce during their lives.

This is the first detailed study of field-evolved Cry1Fa resistance in corn borers, making it a significant finding. Previous research on other pest species has shown that resistance often comes with fitness costs—meaning resistant bugs are weaker or reproduce less. This study is notable because the resistant corn borers actually appear healthier and more reproductive than normal bugs, which is unusual and concerning for pest management.

The study was conducted entirely in laboratory conditions with controlled temperature, food, and living space. Real corn fields have variable weather, different food sources, and natural predators that could affect how well resistant bugs actually survive. The study also didn’t specify exact sample sizes for each group tested. Additionally, the research only examined one resistant population from one location, so results might differ in other geographic areas or if resistance develops through different genetic mechanisms.

The Bottom Line

Agricultural experts and farmers should implement urgent pest management strategies to slow the spread of resistant corn borers. This may include rotating different types of pest control methods, planting non-genetically modified corn varieties in some areas, and monitoring fields for resistant populations. These recommendations have strong scientific support based on this research. (Confidence: High)

Corn farmers, agricultural extension services, seed companies, and agricultural policy makers should prioritize this information. Home gardeners growing small amounts of corn should be aware but face lower risk. Consumers should know that agricultural scientists are actively working on this issue, though it doesn’t require individual action at this time.

The spread of resistant populations could accelerate over multiple growing seasons if no management actions are taken. Changes in pest populations typically become noticeable within 2-5 years of resistance emergence, though the exact timeline depends on how widely resistant bugs are distributed and how quickly they migrate to new fields.

Want to Apply This Research?

  • If you’re a farmer, track the percentage of corn plants showing damage from European corn borers in each field each season. Compare damage levels year-to-year to detect if resistance is spreading in your area.
  • Implement crop rotation strategies by alternating between Bt corn and non-Bt corn varieties in the same field across seasons. This slows resistance development by giving susceptible bugs opportunities to breed and dilute the resistant population.
  • Scout corn fields regularly during the growing season for corn borer damage. Keep detailed records of damage levels, pesticide applications, and corn variety planted. Share this information with local agricultural extension services to help track resistance spread across regions.

This research describes a specialized agricultural issue affecting commercial corn production. The findings are relevant primarily to farmers, agricultural professionals, and policymakers. This is not medical or nutritional advice for consumers. While genetically modified corn with Bt toxins has been used safely for over 25 years, the development of pest resistance is an agricultural management concern that experts are actively addressing. Consumers should not be concerned about the safety of current corn products. Anyone involved in corn farming should consult with local agricultural extension services for specific pest management recommendations for their region.