Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Biotech cotton 8: Bugs 0

20.10.2005


Biotech cotton has beaten back pink bollworm eight years running, reports a team of scientists from The University of Arizona in Tucson.


A cotton boll with a pink boll caterpillar inside. Photo credit: Timothy Dennehy


Cotton fields in Parker Valley, Ariz. Bt cotton is the greener field in the foreground. The whiter swath of cotton in the background is a refuge field of non-Bt cotton. Photo credit: Timothy Dennehy.



The surprising finding is good news for the environment. Arizona farmers who plant the biotech cotton known as Bt cotton use substantially less chemical insecticides than in the past.

Insect pests sometimes evolve resistance to such chemicals in just a few years, a fate that was predicted for biotech crops genetically altered to produce Bt toxin, a naturally occurring insecticide.


"This is the most complete study to date for monitoring resistance to Bt crops," said team leader Bruce E. Tabashnik, the head of UA’s department of entomology, a member of UA’s BIO5 Institute and an expert in insect resistance to insecticides.

"We found no net increase in insect resistance to Bt. If anything, resistance decreased. This is the opposite of what experts predicted when these crops were first commercialized." He added, "I’m definitely surprised."

Tabashnik, Timothy J. Dennehy, a UA Distinguished University Outreach Professor of Entomology and extension specialist and a member of BIO5, and Yves Carriere, UA associate professor of entomology, will publish their research in an upcoming issue of the Proceedings of the National Academy of Sciences.

Bt cotton has been planted in Arizona since 1996. Now more than half of the state’s 256,000 acres of cotton fields are planted with the biotech plants. Without the protection provided by Bt cotton, some fields can have 100 percent of plants infested with pink bollworm caterpillars, which live inside the cotton boll, destroying the crop.

Dennehy said, "In an extreme infestation, you can have every single boll in the field infected." The caterpillars eat the seeds and damage the developing cotton fibers.

In contrast, when the caterpillars eat Bt cotton, they die.

Before the use of Bt cotton became widespread, pink bollworm was one of the top three insect pests of cotton in the Southwest. In 1995, losses from pink bollworm in Arizona cotton were estimated to be $8.48 per acre, totaling $3.4 million statewide. Cotton is grown in eight Arizona counties: Cochise, Graham, La Paz, Maricopa, Mohave, Pima, Pinal and Yuma.

"Moreover, the harsh insecticides used to control pink bollworm resulted in a host of other insect pests becoming more serious problems," Dennehy said.

Everything changed in 1996, he said, when Bt cotton and two other "soft" insect control tactics replaced a large amount of the harsh pesticides used on cotton crops. Spraying less chemical insecticides means more beneficial insects survive, further reducing the need for spraying.

By 2004, pink bollworm losses had fallen to nearly half of earlier levels, $4.34 per acre.

Tabashnik said, "Some of the other pests are not so much of a problem because we’re not killing their natural enemies with insecticides."

Dennehy added, "These soft toxins plus the good bugs acting together have driven pesticide use to historic low levels ... this is a wonderful success of integrated pest management."

Since widespread adoption of Bt cotton in 1997, insecticide use on Arizona’s cotton crops is down 60 percent, said Tabashnik. The reduction in chemical pesticide use saves growers about $80 per acre. According to the Arizona Agricultural Statistics Bulletin, the value of Arizona’s cotton crops for 2004 was estimated at $207 million.

The key to Bt cotton’s continued efficacy is the use of refuges – patches of traditional cotton intermingled with the fields of Bt cotton.

The refuges ensure that the few pink bollworm moths that are resistant to Bt are most likely to mate with Bt-susceptible pink bollworm moths that grew up in the refuges. The offspring from such matings die when they eat Bt cotton.

In contrast, if all of Arizona’s cotton was Bt cotton, only pink bollworm caterpillars that were resistant to the Bt toxin would survive. If resistant pink bollworm moths mated with each other, their offspring would be resistant and could feed on Bt cotton. Bt cotton would then become useless against pink bollworm.

The UA team used a combination of field surveys, laboratory testing and mathematical modeling to determine if pink bollworm had become resistant to Bt cotton.

The team did find Bt-resistant pink bollworm caterpillars in the field, but they were rare.

Tabashnik said that doesn’t mean the insects won’t bite back in the future. "It’s not that pink bollworm can’t beat Bt toxin, but that it hasn’t beaten Bt toxin so far."

There’s a new variety Bt cotton now available that has two different Bt toxins, he said. The team’s next step will be to determine how to best use that combination of toxins to stay one step ahead of the pink bollworms.

Mari N. Jensen | EurekAlert!
Further information:
http://www.arizona.edu
http://bio5.org/

More articles from Life Sciences:

nachricht Symbiotic bacteria: from hitchhiker to beetle bodyguard
28.04.2017 | Johannes Gutenberg-Universität Mainz

nachricht Nose2Brain – Better Therapy for Multiple Sclerosis
28.04.2017 | Fraunhofer-Institut für Grenzflächen- und Bioverfahrenstechnik IGB

All articles from Life Sciences >>>

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

Fighting drug resistant tuberculosis – InfectoGnostics meets MYCO-NET² partners in Peru

28.04.2017 | 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

 
Latest News

Wireless power can drive tiny electronic devices in the GI tract

28.04.2017 | Medical Engineering

Ice cave in Transylvania yields window into region's past

28.04.2017 | Earth Sciences

Nose2Brain – Better Therapy for Multiple Sclerosis

28.04.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>