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 Ammonium nitrogen input increases the synthesis of anticarcinogenic compounds in broccoli
26.04.2017 | University of the Basque Country

nachricht New data unearths pesticide peril in beehives
21.04.2017 | Cornell University

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: Making lightweight construction suitable for series production

More and more automobile companies are focusing on body parts made of carbon fiber reinforced plastics (CFRP). However, manufacturing and repair costs must be further reduced in order to make CFRP more economical in use. Together with the Volkswagen AG and five other partners in the project HolQueSt 3D, the Laser Zentrum Hannover e.V. (LZH) has developed laser processes for the automatic trimming, drilling and repair of three-dimensional components.

Automated manufacturing processes are the basis for ultimately establishing the series production of CFRP components. In the project HolQueSt 3D, the LZH has...

Im Focus: Wonder material? Novel nanotube structure strengthens thin films for flexible electronics

Reflecting the structure of composites found in nature and the ancient world, researchers at the University of Illinois at Urbana-Champaign have synthesized thin carbon nanotube (CNT) textiles that exhibit both high electrical conductivity and a level of toughness that is about fifty times higher than copper films, currently used in electronics.

"The structural robustness of thin metal films has significant importance for the reliable operation of smart skin and flexible electronics including...

Im Focus: Deep inside Galaxy M87

The nearby, giant radio galaxy M87 hosts a supermassive black hole (BH) and is well-known for its bright jet dominating the spectrum over ten orders of magnitude in frequency. Due to its proximity, jet prominence, and the large black hole mass, M87 is the best laboratory for investigating the formation, acceleration, and collimation of relativistic jets. A research team led by Silke Britzen from the Max Planck Institute for Radio Astronomy in Bonn, Germany, has found strong indication for turbulent processes connecting the accretion disk and the jet of that galaxy providing insights into the longstanding problem of the origin of astrophysical jets.

Supermassive black holes form some of the most enigmatic phenomena in astrophysics. Their enormous energy output is supposed to be generated by the...

Im Focus: A Quantum Low Pass for Photons

Physicists in Garching observe novel quantum effect that limits the number of emitted photons.

The probability to find a certain number of photons inside a laser pulse usually corresponds to a classical distribution of independent events, the so-called...

Im Focus: Microprocessors based on a layer of just three atoms

Microprocessors based on atomically thin materials hold the promise of the evolution of traditional processors as well as new applications in the field of flexible electronics. Now, a TU Wien research team led by Thomas Müller has made a breakthrough in this field as part of an ongoing research project.

Two-dimensional materials, or 2D materials for short, are extremely versatile, although – or often more precisely because – they are made up of just one or a...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Expert meeting “Health Business Connect” will connect international medical technology companies

20.04.2017 | Event News

Wenn der Computer das Gehirn austrickst

18.04.2017 | Event News

7th International Conference on Crystalline Silicon Photovoltaics in Freiburg on April 3-5, 2017

03.04.2017 | Event News

 
Latest News

From volcano's slope, NASA instrument looks sky high and to the future

27.04.2017 | Earth Sciences

Control of molecular motion by metal-plated 3-D printed plastic pieces

27.04.2017 | Materials Sciences

Move over, Superman! NIST method sees through concrete to detect early-stage corrosion

27.04.2017 | Materials Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>