Resistance to Bt corn by WCR is a growing concern

decrease font size  Resize text   increase font size       Printer-friendly version of this article Printer-friendly version of this article

A researcher at Iowa State University is urging Iowa farmers to adopt a diverse range of pest management tactics to suppress the resistance of western corn rootworm to Bt corn, a widely used method of keeping a range of pests from ravaging corn crops.

Bt corn derives its name from Bacillus thuringiensis, a bacterium that produces toxins that kill insects. Those toxin-producing genes are genetically engineered into Bt corn, which allows the corn to fight pests such as the rootworm. But starting in 2009, farmers in northeast Iowa began to report rootworm problems despite the use of Bt corn, said Aaron Gassmann (pictured), an ISU assistant professor of entomology.

That year, Gassmann said he confirmed four fields in which rootworms had developed resistance to Bt corn, and resistance problems have persisted in Iowa ever since. Between 2010 and 2013, Gassmann said he’s visited between nine and 25 fields each year where either Bt resistance was confirmed or where western corn rootworm imposed severe feeding injury to Bt corn.

Gassmann, the author of a recently published article in the Proceedings of the National Academy of Science on rootworm resistance, said it’s hard to grasp the full extent of the problem because there has been no systematic random sampling of Iowa cornfields for the resistance. But states like Nebraska, Illinois and Minnesota have confirmed cases of resistance to Bt corn, meaning the issue is of growing concern to American corn producers.

Gassmann said Bt corn has become an important tool for pest management because it has a smaller and more targeted environmental impact than pesticides. It also targets other pests besides rootworm, such as the European corn borer.

“It’s a convenient and safe technology that should remain part of an integrated pest management system,” he said. “But the future of the technology depends on how farmers use it.”

He said planting corn on the same acres season after season – a practice encouraged by high corn prices in recent years – likely accelerated the development of rootworm resistance to Bt corn. Somewhere around three-quarters of U.S. corn is Bt, and, if a rootworm carries the genetic resistance to the toxin, it can spread that gene through reproduction. Crop rotation, however, breaks the lifecycle of rootworms between growing seasons and helps to delay the development of resistance, Gassmann said.

In addition, the use of refuges, or sections of fields in which non-Bt corn is planted, also helps delay the development of Bt resistance. Gassmann also recommended farmers make use of “pyramided” Bt corn, which produces more than one toxin poisonous to pests.

Combining those approaches will result in an integrated approach that slows rootworm resistance and allows farmers to maintain the advantages that Bt corn provides, Gassmann said.


Buyers Guide

Doyle Equipment Manufacturing Co.
Doyle Equipment Manufacturing prides themselves as being “The King of the Rotary’s” with their Direct Drive Rotary Blend Systems. With numerous setup possibilities and sizes, ranging from a  more...
A.J. Sackett Sons & Company
Sackett Blend Towers feature the H.I.M, High Intensity Mixer, the next generation of blending and coating technology which supports Precision Fertilizer Blending®. Its unique design allows  more...
R&R Manufacturing Inc.
The R&R Minuteman Blend System is the original proven performer. Fast, precise blending with a compact foot print. Significantly lower horsepower requirement. Low inload height with large  more...
Junge Control Inc.
Junge Control Inc. creates state-of-the-art product blending and measuring solutions that allow you to totally maximize operating efficiency with amazing accuracy and repeatability, superior  more...
Yargus Manufacturing
The flagship blending system for the Layco product line is the fully automated Layco DW System™. The advanced technology of the Layco DW (Declining Weight) system results in a blending  more...
Yargus Manufacturing
The LAYCOTE™ Automated Coating System provides a new level of coating accuracy for a stand-alone coating system or for coating (impregnating) in an automated blending system. The unique  more...
John Deere
The DN345 Drawn Dry Spreader can carry more than 12 tons of fertilizer and 17.5 tons of lime. Designed to operate at field speeds up to 20 MPH with full loads and the G4 spreader uniformly  more...
Force Unlimited
The Pro-Force is a multi-purpose spreader with a wider apron and steeper sides. Our Pro-Force has the most aggressive 30” spinner on the market, and is capable of spreading higher rates of  more...
BBI Spreaders
MagnaSpread 2 & MagnaSpread 3 — With BBI’s patented multi-bin technology, these spreaders operate multiple hoppers guided by independent, variable-rate technology. These models are built on  more...


Comments (0) Leave a comment 

Name
e-Mail (required)
Location

Comment:

characters left


LPV Seed Treater

The LPV Seed Treater has set a new standard boasting three configurable weighing methods for any-sized operation, a standard 42” ... Read More

View all Products in this segment

View All Buyers Guides

Feedback Form
Feedback Form