IL Researcher Tracks Bt Trait Overuse

High corn prices are leading many growers to plant corn every year and to overuse pesticides and other bug-killing technology to maximize yields, researchers report.

In many instances, pesticides are applied without scouting fields to see if they are needed, violating a bedrock principle of integrated pest management. The result is a biological diversity desert in many corn and soybean fields in the agricultural Midwest, and signs that the surviving insects are becoming resistant to several key bug-fighting tools now available to farmers.

University of Illinois crop sciences professor Michael Gray and his colleagues conducted a survey of corn and soybean pests in 47 counties in Illinois from late July to early August in 2011, and found densities of some key insect pests to be at zero or near zero in many counties.

“I’ve never seen anything like it in 22 years of doing this kind of research,” Gray said. “From an insect diversity perspective, it’s a biological desert in many of those fields.” Even western corn rootworm adults (which normally lay their eggs in cornfields in late summer) were difficult to find in many counties, he said.

In part, these low numbers are the result of environmental conditions – particularly wet springs – the past few years, Gray said. However, the widespread use of Bt-corn hybrids, which produce one or more insecticidal proteins, and the common practice of broadcasting mixes of insecticide and fungicide on corn and soybean fields also plays a role, he said.

And yet, when Gray asks farmers at growers’ meetings if they plan to use Bt corn again this year, a huge majority says yes.“Many producers indicate that in order to have access to high yielding germplasm, the use of Bt hybrids is essential,” Gray said. “It is likely that many growers also will use a soil insecticide at planting, even though a Bt hybrid will be used.” This goes against decades of advice from researchers like Gray who argue for integrated pest management – the careful assessment of bug populations to determine what, if any, treatments are needed, and the use of changing tactics against adaptable pests such as the western corn rootworm and the European corn borer, either of which could devastate corn yields.

“We ask them to consider rotation with soybeans, to spray only when insects are present at levels that are likely to affect yield, and to not use Bt every season, or if they do, to get a different type of Bt corn, one that expresses a different Bt protein,” Gray said.

But instead of using integrated pest management, growers are relying on what he calls “insurance pest management,” throwing everything in their arsenal at the bugs to protect their crop, year after year.

“For corn in Central Illinois, the average non-land costs – things like fertilizer, seed, crop insurance and machinery – come to about $513 an acre,” Gray said. Cash rent can add another $325 an acre for high-yield ground, he said. “So I think a lot of the growers see $20 to $25 dollars to apply a soil insecticide as pretty cheap insurance to protect that $850 investment.”

Landowners are raising rents in this competitive arena, some lenders encourage growers to do everything in their power to protect their yields, and federal incentives have lowered the cost of crop insurance for growers who use Bt corn, Gray said. So there are a lot of reasons for farmers to keep doing what they have been doing.

Most growers are not likely to be alarmed by the low number of bugs, but will instead see it as proof that their strategy works, Gray said. Other evidence, however, suggests that the short-term benefits will lead to unanticipated – and undesirable – consequences.

Researchers are already finding failures of Bt corn against the western corn rootworm in Iowa, Illinois, Minnesota and Nebraska, for example. In a study published in 2011 in the journal PLoS ONE, Aaron Gassmann and his colleagues at Iowa State University demonstrated that the offspring of western corn rootworms from rootworm-damaged cornfields in Iowa were less susceptible to a particular Bt toxin (Cry3Bb1, the type of Bt in use in the damaged fields) than the control population.

Gray has seen the same kind of severe rootworm damage in Illinois fields planted with the Cry3Bb1 variety of Bt corn, and he is collaborating with Gassmann on a new study of the Bt failures in Illinois. As yet, the researchers have not confirmed the cause of these Bt failures and are working to determine the mechanism.

“Like the fields Gassmann studied in Iowa, the failures here in Illinois are in fields planted in continuous corn for many years with no crop rotation, using that same Cry3Bb1 Bt protein over and over again,” Gray said.

Growers’ confidence in Bt corn probably stems from its great success against the European corn borer, a pest accidentally brought to the U.S. in the early 1900s. The insect arrived in Illinois in the late 1930s.

“It was a devastating pest,” Gray said. “It was a major yield robber.”

In a 2010 paper in Science, Gray and colleagues from several Midwestern universities reported that the introduction of Bt corn in 1996 led to a profound and lasting reduction of the European corn borer across the upper Midwest.

This success was in large part due to two factors, Gray said. First, it was relatively easy to get high levels of the Bt proteins in above-ground corn tissues, on which corn borers feed. And second, regulators required farmers who used Bt corn to provide large buffer zones, called refuges, planted with non-Bt corn. The refuges would supply a lot of Bt-susceptible insects to mate with those that survived exposure to Bt and were thus resistant to the toxin, to reduce the development of Bt-resistant strains.

Western corn rootworm larvae do the most damage to roots, however, and expression of Bt toxins in roots is much lower than in above-ground tissues. This means that the rootworms are getting a much lower dose of specific Cry toxins than the corn borers do, Gray said. Add to that the fact that some growers are ignoring the buffer requirement while also planting Bt corn year after year, he said, and you’ve got a recipe for resistance.

“We might not be having this conversation if corn was $3 a bushel and growers were asking us where to put their limited resources,” he said. “But with these high commodity prices the notion of adding inputs to squeeze out a couple of more bushels seems like cheap insurance.”

Gray will present his latest findings at the International Integrated Pest Management Symposium on March 27-29, 2012, in Memphis, TN.

Leave a Reply

Seed/Biotech Stories

Nufarm Seed Treatment lab formulations
Seed/BiotechNew Lab, Company Realignment Strengthen Nufarm’s Position To Serve Seed Treatment Market
October 6, 2016
As part of its “One Nufarm” strategy, Nufarm is realigning and uniting resources to further enhance the focus on its Read More
Soybean Field
Seed/BiotechBayer, West Central Distribution Introduce Fungicde Seed Treatment For Soybeans
October 6, 2016
Bayer and West Central Distribution are introducing a new combination fungicide treatment for soybean plants, Redigo 480 + Trilex, to Read More
Syngenta Seedcare Institute
Seed/BiotechSyngenta Opens New North America Seedcare Institute In Stanton, MN
September 23, 2016
Syngenta unveiled its new Seedcare Institute in Stanton, MN, during a recent grand opening celebration. More than 150 industry leaders, Read More
Corn close up
Crop InputsNY Times: Bayer-Monsanto a Bad Deal for Farmers
September 15, 2016
Via NY Times: Don Halcomb, a 63-year-old farmer in Adairville, KY, is expecting his profit to vanish this year, largely Read More
Trending Articles
AGCO RG700 cab
OpinionRoadblocks To Precision Ag Innovation
October 5, 2016
On August 29, I got to preside over the PrecisionAg Innovation Series event, “Game-Changing Advances in Precision Farming Technology,” developed Read More
J.C. Ramsdell containment system
EquipmentClear Opportunity In The Tank Market
October 4, 2016
Crop prices may be down, but steel prices are too — and that’s good news for retailers looking to add some Read More
WinField booth Farm Progress
Special ReportsTalking Weed Management Strategies At Farm Progress 2016
October 2, 2016
The annual Farm Progress Show — this year staged in Boone, IA — is always a great place to catch Read More
Corn Field
Eric SfiligojFacing Ag Industry Challenges
September 26, 2016
At the 2016 annual Mid America CropLife Association (MACA) meeting in September, a pair of crop protection company representatives discussed Read More
Bayer Monsanto
Crop InputsBayer-Monsanto Mega-Merger: 6 Things You Need To Know
September 14, 2016
Mega mergers have become almost routine in the agricultural industry. Right on the heels of Monday’s news that fertilizer giants Potash Read More
Potash Corp Agrium
Crop InputsAgrium, Potash Corp To Merge To Create $36 Billion Company
September 12, 2016
Canada’s Agrium Inc. and Potash Corp of Saskatchewan Inc. have agreed to combine in a deal that would create a Read More
Latest News
ManagementThe Latest Dow-DuPont Rumor, Product of the Year Voting…
October 20, 2016
CropLife Editor Eric Sfiligoj shares a new rumor about the Dow-DuPont merger and updates on two CropLife-driven programs, the CropLife Read More
Soybean Closeup
FungicidesFMC Begins Registration Process For New Fungicide Activ…
October 19, 2016
FMC Agricultural Solutions has begun the joint U.S. EPA and Canadian Pest Management Regulatory Agency registration process for bixafen, a new Read More
Soil Young Corn
Industry NewsAgribusiness Search Firm Appoints New Managing Partner
October 18, 2016
Morris Bixby Group, a leading agribusiness search firm providing the highest quality professional recruiting and career advancement services since 2000, Read More
Wheat Field North Dakota
FertilizerUnited Suppliers Acquires Kansas Fertilizer Business
October 17, 2016
United Suppliers, Inc. has purchased the assets of Evans Enterprises, LLC, an ammonium chloride fertilizer business based in Olathe, KS. Read More
Corn Field
Industry NewsFMC Launches New Operations In Argentina, Exits Joint V…
October 17, 2016
FMC Corp. has exited its joint venture with Ruralco Soluciones S.A. FMC has launched new commercial operations, FMC Quimica S.A., Read More
Dow AgroSciences
InsecticidesRenewed Registration Issued For Products Containing Sul…
October 17, 2016
On October 14, 2016, the U.S. EPA re-established the registration of products containing sulfoxaflor (Isoclast Active), including Transform WG, Closer Read More
Eric SfiligojThe Whys Of Agriculture
October 17, 2016
During 2016, there have been myriad challenges facing the whole agricultural industry. Such wide ranging issues as water protection, sustainable Read More
Young Corn Field
FertilizerImproved Phosphorus Management Essential To Feeding Wor…
October 14, 2016
With a global population expected to reach 9 billion people by 2050, improved management of key essential nutrients such as Read More
ManagementHarvest and Crop Price Updates; EPA and Crop Protection…
October 13, 2016
Glyphosate and atrazine get public comment support from ARA as each is reviewed by EPA, and the latest on the Read More
Matt Hopkins15 Twitter Accounts Every Ag Professional Must Follow
October 13, 2016
What do singer Katy Perry and the President of the United States have in common? They are two of the Read More
Corn Field
Industry NewsArysta LifeScience Adds Two Key Account Managers
October 13, 2016
Arysta LifeScience North America recently announced the addition of two key account managers: Doug Hoberty and Rob Wier. Hoberty and Read More
EquipmentDeere Announces Development Deal with Scherer Design
October 12, 2016
Deere & Co. announces a joint development agreement with Scherer Design Engineering, Inc. to develop and commercialize kernel processing solutions Read More
Crop InputsMarrone Bio Innovations Celebrates 10 Years Of Innovati…
October 12, 2016
Richard Rominger, former Deputy Secretary of the USDA and former agricultural secretary of California, emceed a 10th anniversary luncheon celebration on Read More
Photo credit: The United Soybean Board/The Soybean Checkoff.
Industry NewsVive Crop Protection Closes Financing To Support Corpor…
October 11, 2016
Vive Crop Protection has announced the closing of growth financing to support 2017 commercial expansion. The financing was led by Read More
SoftwareHD Precision Analytics Launches New Mobile App For Agri…
October 11, 2016
AGSentry from HD Precision Analytics is a Software-as-a-Service (SaaS) platform that offers simple data service and actionable analytics tool. It focuses Read More
HerbicidesWeed Control And Soil Health Go Hand-in-Hand
October 10, 2016
Although many landowners may not give much thought to weed control as a soil health measure, Gared Shaffer, South Dakota Read More
Students Soybean Field
Eric Sfiligoj2016 Young Leaders Speak
October 10, 2016
One of the consistent cries in agriculture today is the need to try and connect with the younger generations, attempting Read More
ManagementVision Conference Preview, Monsanto Earnings, and Produ…
October 7, 2016
Editors Paul Schrimpf and Eric Sfiligoj talk about the upcoming PrecisionAg Vision meeting in Arizona, Monsanto’s latest revenue numbers, and Read More