Western corn rootworm (WCR) and northern corn rootworm (NCR) continue to dominate as economic pests throughout the U.S. and Canada. Recently, high corn rootworm populations and the development of resistance to Bt corn hybrids in some areas has sparked greater interest in scouting and alternative management of corn rootworms. In response, the Corn Rootworm IPM Regional Working Group was formed during the spring of 2021 and continues to grow. Currently, we are made up of university, industry, and government personnel from at least 12 U.S. states and 5 Canadian provinces.

Results summary from abstract: "Collectively, results indicate that northeast Nebraska WCR populations were in the initial stages of resistance evolution to Cry34/35Ab1 during 2018–2019. Appropriate resistance management strategies are needed to mitigate resistance and preserve efficacy of rootworm-active products containing Cry34/35Ab1."

The goal of this research program is to serve the agricultural community of Iowa by monitoring and evaluating the performance of registered and precommercial insecticides and transgenic corn hybrids. To achieve this goal, we maintain a viable, proactive, progressive and scientifically sound product evaluation program.

Western and northern corn rootworms are serious pests of corn throughout the Corn Belt (Photo 1). We recommend that farmers scout every cornfield every year, regardless of the management tactic(s) used, to evaluate management decisions and prepare for next year. It is a good idea to scout for larvae early in the season, assess root injury when larval feeding wraps up, and monitor adults later in the season. Since beetle emergence is underway throughout most of the state, now is a good time to begin planning for monitoring adults with sticky traps.

Western and northern corn rootworm are serious pests of corn throughout the Corn Belt. We recommend that farmers scout every cornfield every year, regardless of the management tactic(s) used, to evaluate management decisions and prepare for next year. It is a good idea to scout for larvae early in the season, assess root injury when larval feeding wraps up, and monitor adults later in the season. Corn rootworm adults have started emerging throughout Iowa, which is an excellent time to evaluate root injury.

Last year, entomologists and field specialists with Iowa State University Extension and Outreach received many questions about effective management of corn rootworms as populations have increased in the past two years and farmers have experienced enhanced root injury during drought conditions. We teamed up with the ISU extension field agronomists to host corn rootworm management field days at 7 ISU Research and Demonstration Farms in 2022. Come join us this summer to learn about corn rootworm identification, sampling, management, and resistance.

Results summary from abstract: "Results from this study collectively suggest that SmartStax^® PRO may negatively impact WCR life history traits, which may lead to reduced population growth when deployed in an area with WCR resistance to Bt traits."

The 2021 Field Crop Insect and Disease Applied Research Report provides farmers with updated control efficacy and pest distribution information for major pests of corn and soybean. Use these evaluations to guide control decisions, track performance over time, and see trends in pest populations.