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 Embryonic development: How do limbs develop from cells?
18.05.2018 | Humboldt-Universität zu Berlin

nachricht Reading histone modifications, an oncoprotein is modified in return
18.05.2018 | American Society for Biochemistry and Molecular Biology

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Explanation for puzzling quantum oscillations has been found

So-called quantum many-body scars allow quantum systems to stay out of equilibrium much longer, explaining experiment | Study published in Nature Physics

Recently, researchers from Harvard and MIT succeeded in trapping a record 53 atoms and individually controlling their quantum state, realizing what is called a...

Im Focus: Dozens of binaries from Milky Way's globular clusters could be detectable by LISA

Next-generation gravitational wave detector in space will complement LIGO on Earth

The historic first detection of gravitational waves from colliding black holes far outside our galaxy opened a new window to understanding the universe. A...

Im Focus: Entangled atoms shine in unison

A team led by Austrian experimental physicist Rainer Blatt has succeeded in characterizing the quantum entanglement of two spatially separated atoms by observing their light emission. This fundamental demonstration could lead to the development of highly sensitive optical gradiometers for the precise measurement of the gravitational field or the earth's magnetic field.

The age of quantum technology has long been heralded. Decades of research into the quantum world have led to the development of methods that make it possible...

Im Focus: Computer-Designed Customized Regenerative Heart Valves

Cardiovascular tissue engineering aims to treat heart disease with prostheses that grow and regenerate. Now, researchers from the University of Zurich, the Technical University Eindhoven and the Charité Berlin have successfully implanted regenerative heart valves, designed with the aid of computer simulations, into sheep for the first time.

Producing living tissue or organs based on human cells is one of the main research fields in regenerative medicine. Tissue engineering, which involves growing...

Im Focus: Light-induced superconductivity under high pressure

A team of scientists of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg investigated optically-induced superconductivity in the alkali-doped fulleride K3C60under high external pressures. This study allowed, on one hand, to uniquely assess the nature of the transient state as a superconducting phase. In addition, it unveiled the possibility to induce superconductivity in K3C60 at temperatures far above the -170 degrees Celsius hypothesized previously, and rather all the way to room temperature. The paper by Cantaluppi et al has been published in Nature Physics.

Unlike ordinary metals, superconductors have the unique capability of transporting electrical currents without any loss. Nowadays, their technological...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Save the date: Forum European Neuroscience – 07-11 July 2018 in Berlin, Germany

02.05.2018 | Event News

Invitation to the upcoming "Current Topics in Bioinformatics: Big Data in Genomics and Medicine"

13.04.2018 | Event News

Unique scope of UV LED technologies and applications presented in Berlin: ICULTA-2018

12.04.2018 | Event News

 
Latest News

Supersonic waves may help electronics beat the heat

18.05.2018 | Power and Electrical Engineering

Keeping a Close Eye on Ice Loss

18.05.2018 | Information Technology

CrowdWater: An App for Flood Research

18.05.2018 | Information Technology

VideoLinks
Science & Research
Overview of more VideoLinks >>>