Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Tests show biotech corn rules need revision

11.05.2004


A corn earworm (Helicoverpa zea) caterpillar damages corn by devouring kernels and spreading green mold (Aspergillus flavus).
Photo credit: Texas A&M University


Biotech corn carrying a gene that confers protection from insects can pollinate corn plants as far as 100 feet (31 meters) away, reports a pair of researchers.

The gene, known as Bt, codes for a toxin that kills corn-munching caterpillars, including European corn borer and corn earworm.

The findings suggest measures are needed to reduce pollen spread from Bt corn to corn fields that should be Bt-free, according to the researchers.



The discovery is important because planting non-Bt corn, which is susceptible to insect attack, near Bt corn delays pest resistance to the Bt toxin. Such fields of non-Bt corn are called refuges.

However, this research indicates a need to revise the current Environmental Protection Agency guidelines for interspersing non-Bt corn with Bt, or transgenic, corn. The gene is from the bacterium called Bt--short for Bacillus thuringiensis.

"It’s the first documentation of gene flow from a transgenic crop into a refuge," said Bruce E. Tabashnik, head of the entomology department at the University of Arizona in Tucson and co-author on the research paper. "This will almost certainly cause a revision of some of the regulations," adding, "I think it’s a problem that once observed, recognized and accepted can be readily overcome."

Tabashnik, who works on the evolution of resistance in insects, was involved in devising the refuge guidelines. Using such biotech crops can reduce the need for chemical insecticides, he said.

"If Bt crops were grown wall-to-wall, everyone would expect resistance in insects to evolve overnight," he said. "The EPA rules say that if you grow Bt corn, you must plant a refuge of non-Bt corn for at least 20 percent of your crop."

Caterpillars that can survive on Bt corn are rare at first, and only a few resistant adult moths emerge from Bt corn fields. But refuges of non-Bt corn produce oodles of susceptible moths. The idea is that the uncommon resistant moths will mate with the more abundant susceptible moths. Their hybrid progeny would be killed by feeding on Bt corn. Thus, Bt resistance would not increase quickly.

Non-Bt corn refuges must be close to Bt corn so Bt-resistant moths will almost certainly mate with only with Bt-susceptible moths from refuges.

Until now, researchers didn’t consider that the Bt and non-Bt corn plants were also close enough to mate, potentially reducing the amount of non-Bt corn in the refuge.

The research article, "Contamination of refuges by Bacillus thuringiensis toxin genes from transgenic maize," will be published the week of May 10 in the online early edition of the Proceedings of the National Academy of Sciences. First author on the paper is Charles F. Chilcutt of Texas A&M University’s Texas Agricultural Research & Extension Center in Corpus Christi. Research support was provided by the University of Arizona and Texas A&M University’s Texas Agricultural Research & Extension Center.

Chilcutt questioned whether pollen from Bt corn moved into refuges when he noticed that ears of white non-Bt corn had some yellow kernels. Yellow kernels meant the plants had been pollinated by yellow, not white, corn. The plot of white corn had been planted near yellow Bt corn.

So he tested those yellow kernels for the Bt toxin and found it in high levels.

To see how far Bt corn pollen could spread, he planted eight rows of Bt corn next to 36 rows of non-Bt corn. The rows were planted 38 inches apart. At the end of the growing season, he took ears from the non-Bt corn and tested them for Bt toxin.

In the first few rows of corn that was supposed to be Bt-free, the ears had almost half as much Bt as the Bt corn. Although corn in more distant rows had less Bt, there was detectable Bt in the ears of corn planted 32 rows away from the plot of Bt corn.

Chilcutt said, "There’s very good chance that if any grower is growing four rows of Bt corn and four rows of non-Bt corn -- 4-4-4-4 -- essentially all the refuge plants could be contaminated."

Current regulations allow such spacing between Bt and non-Bt corn.

He added, "It could increase the speed with which insect populations become resistant to the toxin."

Tabashnik said, "The possibility of toxin production in the refuge plants is something that needs to be incorporated into the science and the regulations."

Because corn is wind-pollinated, refuges could be planted upwind of Bt corn, suggests Tabashnik. Another possibility would be blocking cross-pollination by planting a variety of Bt corn that produces pollen when the non-Bt corn is not receptive.

Tabashnik said, "The problem will take more research to be fully understood, but it’s not catastrophic and can be overcome with relatively minor refinements."

Bruce Tabashnik | University of Arizona
Further information:
http://www.arizona.edu/

More articles from Agricultural and Forestry Science:

nachricht Cereals use chemical defenses in a multifunctional manner against different herbivores
06.12.2018 | Max-Planck-Institut für chemische Ökologie

nachricht Can rice filter water from ag fields?
05.12.2018 | American Society of Agronomy

All articles from Agricultural and Forestry Science >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Lethal combination: Drug cocktail turns off the juice to cancer cells

A widely used diabetes medication combined with an antihypertensive drug specifically inhibits tumor growth – this was discovered by researchers from the University of Basel’s Biozentrum two years ago. In a follow-up study, recently published in “Cell Reports”, the scientists report that this drug cocktail induces cancer cell death by switching off their energy supply.

The widely used anti-diabetes drug metformin not only reduces blood sugar but also has an anti-cancer effect. However, the metformin dose commonly used in the...

Im Focus: New Foldable Drone Flies through Narrow Holes in Rescue Missions

A research team from the University of Zurich has developed a new drone that can retract its propeller arms in flight and make itself small to fit through narrow gaps and holes. This is particularly useful when searching for victims of natural disasters.

Inspecting a damaged building after an earthquake or during a fire is exactly the kind of job that human rescuers would like drones to do for them. A flying...

Im Focus: Topological material switched off and on for the first time

Key advance for future topological transistors

Over the last decade, there has been much excitement about the discovery, recognised by the Nobel Prize in Physics only two years ago, that there are two types...

Im Focus: Researchers develop method to transfer entire 2D circuits to any smooth surface

What if a sensor sensing a thing could be part of the thing itself? Rice University engineers believe they have a two-dimensional solution to do just that.

Rice engineers led by materials scientists Pulickel Ajayan and Jun Lou have developed a method to make atom-flat sensors that seamlessly integrate with devices...

Im Focus: Three components on one chip

Scientists at the University of Stuttgart and the Karlsruhe Institute of Technology (KIT) succeed in important further development on the way to quantum Computers.

Quantum computers one day should be able to solve certain computing problems much faster than a classical computer. One of the most promising approaches is...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

ICTM Conference 2019: Digitization emerges as an engineering trend for turbomachinery construction

12.12.2018 | Event News

New Plastics Economy Investor Forum - Meeting Point for Innovations

10.12.2018 | Event News

EGU 2019 meeting: Media registration now open

06.12.2018 | Event News

 
Latest News

New discoveries predict ability to forecast dementia from single molecule

12.12.2018 | Health and Medicine

CCNY-Yale researchers make shape shifting cell breakthrough

12.12.2018 | Physics and Astronomy

Pain: Perception and motor impulses arise in the brain independently of one another

12.12.2018 | Health and Medicine

VideoLinks
Science & Research
Overview of more VideoLinks >>>