U.S. Entomologists Call on Seed Industry to Admit Failings of GM Herculex Corn


Dear Friends and Colleagues

U.S. Entomologists Call on Seed Industry to Admit Failings of GM Herculex Corn

The toxin Cry1F is used extensively to confer insect resistance in genetically modified (GM) crops by the major seed companies and across multiple brands (Item 1).Dow AgroScience and DuPont Pioneer call it the Herculex I trait. Cry1F received regulatory approval in 2001 and marketing literature by the companies subsequently claimed it gives protection against the western bean cutworm (WBC), a serious pest of corn.

A group of six entomologists from Michigan, Ohio, Indiana, New York and Pennsylvania has released an open letter (Item 2) asking seed companies to remove the designation of “control” for WBC with regard to Cry1F. The reason for this, they cite, is the failure of Cry1F to control the rapid infestation of WBC in their states. The entomologists said that they have been flooded with reports of severe WBC infestations this summer in Herculex-traited corn in Michigan, Indiana, Ohio and New York. "Wherever Cry1F is challenged by WBC, it fails to provide observable benefit to producers," cites the letter.

The writers call on the seed industry to classify Cry1F hybrids for WBC the same as non-Bt or Cry1Ab—all of which provide no control for WBC—in hybrid fact sheets, technical use agreements, and other educational materials; as well as to regard WBC as a primary, not a secondary, pest. This would reduce grower expectations of Cry1F, so that they continue to scout for egg masses or larvae in the fields, and spray with foliar insecticides if necessary, the same as a non-Bt corn.


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Item 1


Emily Unglesbee, DTN Staff Reporter
DTN The Progressive Farmer, Oct 5 2016

Entomologists are sounding the alarm that Cry1F, Dow AgroScience’s and DuPont Pioneer’s aboveground Herculex I trait, is no longer effective at controlling western bean cutworm.

Cry1F is used extensively as an aboveground trait among the major seed companies and across multiple brands, including Smartstax (Monsanto and Dow) Powercore (Dow), most Acremax (Pioneer) hybrids and many Agrisure (Syngenta) hybrids. The technology is also licensed to many regional corn seed companies.

Led by Michigan State University entomologist Chris DiFonzo, a group of six entomologists from Michigan, Ohio, Indiana, New York and Pennsylvania have released a letter asking Dow and its licensees to change marketing claims and label language to reflect the widespread failures of Cry1F on this particular insect in these states in 2016.

"This trait has now undergone a major test against western bean cutworm, across millions of acres and different biomes and I think it’s failed," DiFonzo told DTN. "After hearing from many voices from the field, we have taken the unusual step as a group to recommend, in writing, that seed companies take a serious look at the failure of the Cry1F Bt trait on western bean cutworm, before sales ramp up for 2017," DiFonzo went on to write in the letter released late Tuesday night.

Dow AgroSciences released a statement to DTN from biology team leader Brad Hopkins confirming that some of their growers have reported "greater feeding damage than in past years under high-pressure conditions and reduced sensitivity of the pest to Cry1F." The company maintains that Cry1F is "an additional tool" for managing western bean cutworm, but added that growers who saw damage this year should consider adding moth flight monitoring, pheromone traps, scouting and insecticide applications to their management plan for the pest in the future.

Marketing Claims Under Fire

The letter DiFonzo released was originally sent to Dow in early September. "There was no response for weeks," DiFonzo said. Finally, company representatives arranged a breakfast meeting with several field crop entomologists as well as a DuPont Pioneer representative at the Entomological Society of America’s annual meeting in Orlando, Florida, on Sept. 29.

Once there, Dow and Pioneer representatives acknowledged reports of Cry1F failures against western bean cutworm, said Ohio State University Extension entomologist Andy Michel, who was present at the meeting. "We did not get any denials that the trait was failing," he said.

The companies’ representatives told the entomologists that it was difficult to make label change, but Pioneer had plans to downgrade marketing descriptions of Cry1F’s control of western bean cutworm to "moderate levels of protection" in the trait’s "product use guide," said Ohio State University entomologist Kelley Tilmon, who also attended the meeting.

The entomologists were not impressed.

"It doesn’t seem like it has any teeth to it," Tilmon said of the new language. "What does ‘moderate’ mean, when in some places it doesn’t work at all?"

The company representatives also stressed that western bean cutworm was not designated as a primary pest of corn, but rather a secondary pest, a categorization that DiFonzo disputes.

"If this is a secondary pest, why is it taking up a primary amount of my time?" she said. "Why is this a primary research area for scientists in Ontario and Michigan? Why is it a primary source of our Extension phone calls?"

Trait Failures

DiFonzo and the other entomologists said they were flooded with reports of severe western bean cutworm infestations this summer in Herculex-traited corn in Michigan, Indiana, Ohio and New York. The ear damage has created some serious ear mold and grain quality issues, Michel said.

Michel ran genetic strip tests on many samples of the WBC-damaged corn and confirmed that they were expressing the Cry1F protein and were not non-Bt refuge ears.

"For our purposes, we’re treating Cry1F as something that is not going to work for western bean cutworm control, and we will tell farmers that if you are using Cry1F, you still have to scout your fields and use insecticides, because there is the potential for heavy feeding," Michel told DTN.

The entomologists’ letter drove this point home: "…our extension recommendations (including the Handy Bt Trait Table) will be changing to classify Cry1F hybrids for WBC the same as non-Bt, Cry1Ab, or double/ triple pro hybrids all of which provide no control [of western bean cutworm]."

Many corn growers in northwest Ohio, where the damage was worst, are scrambling to lock down hybrids with Syngenta’s Vip3a protein (Agrisure Viptera), the only Bt protein currently on the market that is still effective against western bean cutworm, Michel said. But Viptera hybrids can be hard to find in the Great Lakes geography, he added.

When Cry1F was first released in 2001, it was not labeled for use against the western bean cutworm, which was a pest mostly limited to the western fringes of the Corn Belt, DiFonzo recalled.

Over the next decade, the pest began to move deeper into the Midwest, eventually establishing itself as a threat to cornfields as far east as New York and Pennsylvania and as far north as Ontario.

Only then was the western bean cutworm added to the Cry1F label. To date, Dow’s website classifies it as an "above-ground, in-plant, insect protection trait that offers protection against western bean cutworm."

In reality, the trait was never very effective against western bean cutworm, entomologists told DTN. For the past three years, Michel said he has seen steadily increasing damage on Herculex corn from the pest.

The widespread damage found in 2016 could have been exacerbated by the use of 5% or 10% refuge-in-a-bag hybrids, which allows insects to feed on a mosaic of Bt and non-Bt-traited kernels of varying toxin strength, DiFonzo noted. No research yet exists to prove this, but the industry practice of RIB has been shown to accelerate Bt resistance in ear feeding pests (see DTN’s coverage of this phenomenon here:

Item 2


by Cornell Field Crops

This open letter was prepared by the undersigned extension entomologists from the Great Lakes Region regarding the efficacy of the Cry1F (Herculex 1, TC1507) trait on western bean cutworm (WBC; Striacosta albicosta). We strongly urge seed companies to remove the designation of “control” for this pest with regard to this toxin.

At the time Cry1F received regulatory approval in 2001, western bean cutworm was found in the far western Corn Belt (Colorado, Idaho, Nebraska, and Wyoming), with occasional movement into western Iowa. Indeed, EPA’s original Biopesticide Registration Action Document (BRAD) for Cry1F Bt corn, published in August 2001, did not even mention WBC. Instead, the following language was used: “The registrant-submitted data indicate that Cry1F protected corn offers excellent control of European corn borer, southwestern corn borer, fall armyworm, black cutworm, and suppression for the corn earworm.” References to Cry1F giving “excellent protection” against WBC began to appear in marketing literature only after Iowa State University entomologists documented its eastward range expansion and the first economic damage in that state. Presumably this rating was based on a limited number of lab assays and field trials done in pure Bt stands, not Refuge-in-a-Bag hybrids.

The rapid eastward range expansion of WBC across the central Corn Belt into the Great Lakes Region resulted in a dramatic increase in the number of WBC-infested acres in a short time period. This created a large-scale ‘efficacy test’ of Cry1F hybrids to (as stated in the BRAD) “provide highly efficacious control of key Lepidopteran pests”, “reduce the use of more toxic chemical insecticides” and “reduce levels of mycotoxin in corn”. In all these regards, Cry1F has failed in our states. This season in particular, the level of larval infestation and damage is troubling in both single and pyramided Refuge-in-a-Bag hybrids from multiple seed companies. Wherever Cry1F is challenged by WBC, it fails to provide observable benefit to producers. We have collectively fielded dozens of phone calls and emails, and visited numerous fields; we know that our agribusiness contacts and seed industry agronomists have responded to many more, and corn acres were sprayed with both insecticides and fungicides (most too late and with little hope of benefit). People are frustrated and angry and, more importantly, yield was lost. Growers purchased Cry1F hybrids with the understanding that the trait provides “control”, thus negating the need to scout for egg masses or larvae in those fields. When the visible manifestations of damage became apparent late in the season, such as the intense ear-feeding we witnessed, it was far too late for rescue treatments. As the fall progresses and damaged corn is harvested, additional issues are sure to arise regarding quality and mycotoxin levels. The severity of the latter will largely be dependent on weather conditions favorable for ear mold development. What is certain is that many damaged ears are primed for fungal colonization and quality loss.

As extension educators and specialists, we can no longer refer to Cry1F as providing WBC control. In fact the opposite is true, and our extension recommendations (including the Handy Bt Trait Table) will be changing to classify Cry1F hybrids for WBC the same as non-Bt, Cry1Ab, or double/ triple pro hybrids, all of which provide no control. In other words, we believe that Cry1F fields must be scouted for egg masses and sprayed with foliar insecticides if needed, the same as a non-Bt corn. Western bean cutworm is now the PRIMARY Lepidopteran ear pest in many parts of the Great Lakes region. For growers in our states, the costs of scouting and spraying Cry1F corn negates a major reason they purchased and planted a hybrid with the trait in the first place.

Before growers make seed choices for 2017, we again urge the seed industry to acknowledge the reality of what is happening in the field, and to reclassify Cry1F in hybrid fact sheets, technical use agreements, and other educational materials. This would reduce grower expectations of Cry1F and allow local agricultural professionals to deal with their customers in a more truthful manner, in a way that allows for protection against yield loss. We also urge the industry to regard western bean as a primary, not a secondary, pest. Doing nothing risks alienating those close to the situation, including field agronomists, consultants, university extension staff and (most importantly) corn growers themselves who have a vested interest in finding effective pest management solutions for a growing world.


Dr. Chris DiFonzo, Michigan State University
Dr. Christian Krupke, Purdue University
Dr. Andy Michel, The Ohio State University
Dr. Elson Shields, Cornell University
Dr. Kelley Tilmon, The Ohio State University
Dr. John Tooker, Pennsylvania State University

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