DuPont Pioneer, a major agricultural company, has significantly revised its stance on the effectiveness of the Cry1F (Herculex I) Bt trait in corn. In a notable shift from previous claims, Pioneer now states that this trait does not protect corn against the western bean cutworm. This change is reflected in their marketing materials, where all references to control or suppression of this pest are being removed for products with the Herculex I trait. As stated on the company’s website, “All references to control or suppression of western bean cutworm are being completely removed from bag tags, competitive trait tables, product use guides and other customer facing materials.”

This alteration in messaging follows a concerted effort by entomologists who have challenged the companies’ claims about Cry1F’s effectiveness. Pioneer’s Media Relations Manager Susan Mantey remarked, “DuPont Pioneer research shows a widespread decrease in susceptibility in many western bean cutworm populations, indicating the possibility of field evolved resistance to Cry1F in most geographies.” Similarly, Dow AgroSciences, a co-registrant of the trait, is planning to update its marketing language to reflect these findings.

Michigan State University Extension Entomologist Chris DiFonzo notes that now only Syngenta’s Viptera trait, Vip3A, fully controls the western bean cutworm. She warns, “The Vip trait looks really good still. But we need to be cautious — we don’t want to lose that trait, too.”

The original purpose of the Cry1F trait, introduced in 2001, was to target the European corn borer. It was not until 2003 that western bean cutworm was added to the trait’s marketing language, as it became a more significant pest. However, Pioneer scientists never claimed full control of the western bean cutworm by Cry1F, recognizing its moderate susceptibility and high variation in field populations.

The EPA also acknowledged the trait’s limited efficacy against this pest. “EPA determined in 2003 that Cry1F would likely suppress but not control Western bean cutworm because the trait was not high dose,” the agency communicated to DTN.

This development marks an unprecedented move in the realm of Bt trait marketing, with companies modifying their language to account for Bt resistance. Chris DiFonzo considers this a significant shift: “This is uncharted territory. I haven’t seen anything like this change before with a trait.”

For further details, read the full article by Emily Unglesbee, DTN Staff Reporter.