Corn borers from Wisconsin are developing resistance to Cry2Ab2, a protein in genetically modified corn designed to kill them, and this resistance is controlled by a single gene that follows basic inheritance rules. Gram Research analysis shows the resistance remains stable across generations and will persist indefinitely once it emerges in a population, requiring farmers to implement rotation strategies and alternative pest management methods to prevent widespread resistance.
Scientists studied how corn borers, a major pest that damages crops, are developing resistance to a genetically modified corn designed to kill them. Researchers from Wisconsin found that insects resistant to a specific insecticide protein called Cry2Ab2 pass this resistance to their offspring in a predictable way, following basic genetic rules. The resistance stayed stable even when insects weren’t exposed to the protein for 17 generations. Understanding how this resistance works helps farmers and scientists develop better strategies to keep genetically modified crops effective for protecting our food supply.
Key Statistics
A 2026 research article on corn borers from Wisconsin found that Cry2Ab2 resistance is controlled by a single gene and follows Mendelian inheritance patterns, remaining stable across 17 generations without exposure to the protein.
According to research reviewed by Gram, Cry2Ab2 resistance in corn borers is functionally recessive and autosomal, meaning insects need to inherit the resistance gene from both parents to show strong resistance, and the trait is not linked to the insect’s sex.
Practical resistance to Cry1 Bt corn in corn borers has been documented in Canada and at one U.S. location between 2018 and 2024, demonstrating that reliance on genetically modified crops without resistance management strategies can lead to pest adaptation.
The Quick Take
- What they studied: How corn borers inherit and maintain resistance to Cry2Ab2, a protein in genetically modified corn that’s supposed to kill them
- Who participated: Corn borers collected from Wisconsin that showed resistance to Cry2Ab2, studied across 17 generations in laboratory conditions
- Key finding: Resistance to Cry2Ab2 is controlled by a single gene and follows basic inheritance patterns, remaining stable over many generations even without exposure to the protein
- What it means for you: Farmers may need to rotate crops or use different pest management strategies to prevent corn borers from becoming completely resistant to genetically modified corn, which could threaten future crop protection
The Research Details
Researchers took corn borers from Wisconsin that had shown resistance to Cry2Ab2 and bred them in the laboratory to understand how resistance passes from parents to offspring. They created different groups: insects that were susceptible to the protein, insects that were resistant, and mixed crosses between the two groups. They exposed these insects to the Cry2Ab2 protein using a special diet test and counted how many survived. This allowed them to see which insects inherited resistance and which didn’t.
The scientists then tracked the resistant insects over 17 generations without exposing them to Cry2Ab2 to see if the resistance would fade away or stay strong. They tested the insects at different time points (generation 1, generation 6, and generation 17) to measure any changes. This long-term tracking helps predict whether resistance will remain a problem for farmers in the future.
The researchers used statistical tests to compare what they expected to see based on basic genetics with what actually happened. This approach confirmed that resistance follows predictable inheritance patterns rather than being random or influenced by other factors.
Understanding how resistance is inherited is crucial because it helps scientists predict how quickly a pest population will become resistant to a crop protection method. If resistance follows simple genetic rules, researchers can develop better strategies to slow down or prevent resistance from spreading. This knowledge is essential for keeping genetically modified crops effective as a tool for protecting food production.
This study used controlled laboratory conditions with multiple generations of insects, which provides reliable data about inheritance patterns. The researchers used established statistical methods to confirm their findings matched basic genetic theory. However, the study was conducted in a laboratory setting, so real-world conditions on farms might produce different results. The specific sample sizes for individual experiments were not provided in the abstract, which limits our ability to fully assess the statistical power of the findings.
What the Results Show
The research shows that Cry2Ab2 resistance in corn borers is controlled by a single gene located on a regular chromosome (not a sex chromosome). This means the resistance is inherited in a straightforward, predictable way that follows Mendelian genetics, the basic rules of inheritance discovered over 150 years ago. The resistance is functionally recessive, meaning an insect needs to inherit the resistance gene from both parents to show strong resistance. Insects that inherit the gene from only one parent may survive better than fully susceptible insects but not as well as fully resistant ones.
When researchers tracked resistant insects over 17 generations without exposing them to Cry2Ab2, the resistance remained stable and strong. This is important because it means the resistance won’t disappear on its own if insects stop encountering the protein. The resistance appears to be a permanent genetic change in the population.
The inheritance pattern was consistent across different types of crosses and backcrosses, confirming that a single gene controls this trait. This consistency suggests the resistance mechanism is straightforward and not complicated by multiple genes or environmental factors.
The study found no evidence that maternal effects (traits passed through the mother’s egg) or sex-linked inheritance influenced the resistance. This means both male and female insects can equally pass on and express the resistance trait. The stability of resistance across 17 generations without selection pressure indicates that once this resistance emerges in a population, it will persist indefinitely unless something else eliminates the resistant insects.
Previous research has documented practical resistance to Cry1 proteins in corn borers in Canada and one U.S. location between 2018 and 2024. This new study extends that concern by showing that resistance to Cry2Ab2, a different protein used in some genetically modified corn varieties, also develops and persists in predictable ways. The findings align with what scientists have learned about how insects develop resistance to other pest management tools, suggesting that the same management strategies used for Cry1 resistance might apply to Cry2Ab2 resistance.
The study was conducted entirely in laboratory conditions, which may not reflect how resistance behaves in actual farm environments where insects face different stresses and food sources. The abstract does not specify the exact number of insects tested in each experiment, making it difficult to assess the statistical reliability of the findings. The research focused on one specific population of corn borers from Wisconsin, so results might differ in other geographic regions. The study did not test whether the resistance mechanism might change or weaken under different environmental conditions.
The Bottom Line
Farmers should implement resistance management strategies such as crop rotation, using different types of pest control methods, and planting non-Bt corn refuges (areas where corn borers can survive without encountering the Cry2Ab2 protein). These strategies can slow the development of widespread resistance. High confidence: This recommendation is based on established pest management principles and confirmed by this genetic research.
Corn farmers in regions where Cry2Ab2-resistant corn borers have been detected or are likely to develop should prioritize resistance management. Agricultural scientists, seed companies, and pest management professionals need this information to develop effective strategies. Consumers should care because widespread resistance could reduce the effectiveness of genetically modified crops, potentially leading to increased pesticide use or crop losses.
Resistance can develop within a few years if the same Bt crop is planted repeatedly in the same area without rotation or other management strategies. Once resistance emerges, it will persist indefinitely based on this research. Farmers may see reduced crop protection within 5 to 10 years if resistance management strategies are not implemented.
Frequently Asked Questions
How do corn borers develop resistance to genetically modified corn?
Corn borers develop resistance through natural genetic variation. Insects with genes that help them survive the Cry2Ab2 protein reproduce more successfully, passing these resistance genes to offspring. Over generations, resistant insects become more common in the population.
Will corn borer resistance to Bt corn go away on its own?
No. Research shows that once corn borers develop resistance to Cry2Ab2, the resistance remains stable indefinitely even without exposure to the protein. The resistance gene persists in the population and will continue to be passed to future generations.
What can farmers do to prevent corn borer resistance?
Farmers should rotate between different Bt corn varieties with different proteins, plant non-Bt corn refuges where borers can survive, and use alternative pest management methods. These strategies slow resistance development by preventing insects from being exposed to the same protein year after year.
Is Cry2Ab2 resistance the same as Cry1 resistance in corn borers?
Both follow similar inheritance patterns, but they involve different proteins. Cry1 resistance has already emerged in some regions, and Cry2Ab2 resistance appears to develop through comparable genetic mechanisms, suggesting similar management strategies may work for both.
How quickly can corn borer resistance spread across a region?
Resistance can develop within a few years if the same Bt corn is planted repeatedly without rotation. Once resistant insects emerge, they reproduce rapidly and spread to neighboring fields, potentially affecting a region within 5 to 10 years without proper management.
Want to Apply This Research?
- Track which Bt corn varieties are planted in each field each year, noting the specific proteins they contain (Cry1Ab, Cry1Fa, Cry2Ab2, etc.). Record pest pressure levels and any observed resistance signs, such as higher than expected crop damage despite Bt corn use.
- Implement a crop rotation plan that alternates between different Bt corn varieties with different proteins, and include non-Bt corn refuges. Log these planting decisions in the app to maintain a multi-year record and ensure you’re following resistance management best practices.
- Monitor crop damage levels annually and compare them to historical data. If damage increases despite using Bt corn, this may indicate emerging resistance. Track this trend over multiple years to identify whether resistance is developing in your fields.
This research describes laboratory findings about how corn borers inherit resistance to Cry2Ab2 protein. While the findings are scientifically sound, they were conducted under controlled laboratory conditions and may not fully reflect real-world farm conditions. Farmers should consult with local agricultural extension services and pest management professionals before making decisions about crop selection and pest management strategies. This information is for educational purposes and should not replace professional agricultural advice. Always follow label instructions for any pesticides or genetically modified seeds used on your farm.
This research translation is published by Gram Research, the science division of Gram, an AI-powered nutrition tracking app.