Corn rootworm egg hatch in Iowa typically occurs from late May to the middle of June, with an average peak hatching date of June 6 in central Iowa. Development is driven by soil temperature and measured by growing degree days (GDDs). Research suggests about 50% of egg hatch occurs between 684-767 accumulated GDDs (since January 1; base 52°F, soil). Most areas within Iowa have reached peak egg hatch for corn rootworm, and we have heard several reports of folks finding larvae by digging roots in cornfields.

The Canadian Bt Corn Trait Tables have been updated for March 2023. These tables include all registered Bt Corn Trait Packages and indicates which Bt proteins and herbicide tolerant traits they contain and pests they target. These tables also include known resistance status for each pest and Bt protein. This article contains links to English and French versions of the tables.

This 2-page document list the types of Bt present in all commercialized corn in the U.S.A. in a concise format. It presents the trade names for traits, Bt event, protein(s) expressed, targeted insects, and herbicide traits. Now in its 21st year, the Trait Table for field corn has become the standard as an authoritative reference to Bt toxins in corn. Be sure to check out the new supplemental documents for the trait table, including a checklist of Bt events by stack, table of Bt events, and EPA registration numbers.

Tracey Baute from Ontario publishes an infographic with key takeaways from the corn rootworm monitoring network in 2022.

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.