Crops News

Bt resistance emerging from western corn rootworm


Biotechnology traits against rootworm aren’t what they used to be — and it hasn’t taken long for that to happen.

Andy Michel and Kelley Tilmon with Ohio State University Extension recently released a document highlighting the western corn rootworm’s resistance to Bt traits. The extension experts noted that the highly adaptable insect has been causing many field failures in the Western Corn Belt.

Resistance has been discovered to Cry3Bb1 in 2011, mCry3A in 2014, and now Cry34/35Ab1 in 2016. (For a full list of Bt traits see:

“In just 13 years, most of our major tools have been compromised” the authors said. “Currently there is only one trait, eCry3.1Ab (present in Duracade traits), without any published reports of resistance.”

The resistance hasn’t emerged everywhere, and some of these traits are still effective in protecting against root damage in certain regions. However, it is worth being on guard.

“Observations from the Western Corn Belt indicate that a lack of rotation greatly increases the risk of Bt resistance” Michel and Tilmon said. “Any field with corn grown from more than 3 straight years should be inspected for root feeding and proper trait performance.”



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