Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Scientists Find New Way to Assess Where Cotton-Killing Pests Develop

04.12.2002


In a finding that could have broad implications for farmers’ ability to stop pests from decimating cotton crops, scientists from North Carolina State University and agricultural research stations in the Cotton Belt have developed a new technique to determine where the larvae of certain agricultural pests develop.



The study, which looks at the characteristics of the moths that the larvae turn into, shows that a large majority of late-season moths in the Cotton Belt - specifically Helicoverpa zea, a major pest of cotton commonly known as the cotton bollworm - are not developing on cotton and soybean plants, as the prevailing theory suggests, but are developing instead on plants like corn.

The research suggests that this non-toxic corn, therefore, provides a major refuge for H. zea moths, and as such is critical to halting the evolution of insecticide-immune pests, perhaps more so than existing small cotton refuges.


The scientists published their work in Proceedings of the National Academy of Sciences.

Although it seems counterintuitive, non-toxic refuges are essential to controlling pests like the cotton bollworm because the pests that come from these refuges have little to no immunity to toxins. It is estimated that about 80 to 95 percent of cotton bollworms are killed by transgenic cotton plants that produce Bt toxin - derived from the bacterium Bacillus thuringiensis - leaving a fair number of potentially immune caterpillars moving about. When these immune pests mate with pests from non-toxic plants, offspring are not immune to the Bt toxin, and are likely susceptible to die a Bt toxin-induced death.

The scientists - including NC State’s Dr. Fred Gould, William Neal Reynolds Professor of entomology, and Dr. Neal Blair, professor of marine, earth and atmospheric sciences; representatives from the USDA’s Southern Crops Research Lab in College Station, Texas, and the Louisiana Agricultural Experiment Station in Bossier City, La.; and two NC State students -used a novel technique called stable isotope assessment to gauge the origination of moths in late summer. The work was supported by the USDA Biotechnology Risk Assessment Program and the W.M. Keck Center for Behavioral Biology.

The scientists compared the ratios of carbon isotopes 13C and 12C in moths captured over three- and four-year periods from August to October in areas of Louisiana and Texas. These so-called stable isotopes are present in every living organism and in the air. Plants with a certain type of photosynthesis - those with C3 physiology, like cotton - are more depleted in 13C relative to 12C than plants with C4 physiology, like corn. Thus, looking at these ratios in moth wing tissue can provide clues to where the moths grew up, the researchers assert.

And knowing where the moths develop gives researchers clues to how refuges - plants that are not treated with insecticides - are working to put the brakes on the evolution of pests that are genetically resistant to insecticides.

Currently, about 60 percent of cotton grown in the Cotton Belt contains Bt toxin. The Environmental Protection Agency allows the planting of 50 percent Bt corn in cotton-growing areas, as opposed to 80 percent Bt corn in regions where cotton is not grown, Gould says. This policy assumes that H. zea moths migrate from the Cotton Belt to northern Corn Belt states in the summer, but do not return in the fall.

But, since less than 50 percent of late-season moths captured in the study were fed as larvae on cotton, they may be migrating from the Corn Belt, Gould says. This means the traditional assumptions about late-season H. zea moths - that they grow up on cotton, migrate to northern Corn Belt states and then die - seem to be wrong.

"Corn is most likely serving as the predominant alternate C4 host for H. zea," the paper asserts. "Currently, less than 25 percent of U.S. corn produces Bt toxin. If, in the future, most field corn planted in the northern and southern United States remains in non-Bt producing varieties, it could serve as a major H. zea refuge. Maintaining the current limit of 50 percent non-Bt corn in cotton-growing areas therefore seems appropriate for maintaining the long-term utility of Bt cotton."

"In the short term, this is good news for cotton farmers," Gould says. "It shows that corn can provide a refuge so cotton farmers don’t have to increase the non-toxic cotton refuge."

Gould says that problems can set in if Bt corn begins becoming ubiquitous in the Corn Belt. Fewer refuge plants - non-Bt corn, in this case - could allow pests’ resistance to Bt toxin to evolve more quickly, he says.

Dr. Fred Gould | EurekAlert!
Further information:
http://www.ncsu.edu/news/press_releases/02_12/317.htm

More articles from Agricultural and Forestry Science:

nachricht Robotic weeders: to a farm near you?
10.01.2018 | American Society of Agronomy

nachricht Alfalfa loss? Annual ryegrass is a win
03.01.2018 | 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: The first precise measurement of a single molecule's effective charge

For the first time, scientists have precisely measured the effective electrical charge of a single molecule in solution. This fundamental insight of an SNSF Professor could also pave the way for future medical diagnostics.

Electrical charge is one of the key properties that allows molecules to interact. Life itself depends on this phenomenon: many biological processes involve...

Im Focus: Paradigm shift in Paris: Encouraging an holistic view of laser machining

At the JEC World Composite Show in Paris in March 2018, the Fraunhofer Institute for Laser Technology ILT will be focusing on the latest trends and innovations in laser machining of composites. Among other things, researchers at the booth shared with the Aachen Center for Integrative Lightweight Production (AZL) will demonstrate how lasers can be used for joining, structuring, cutting and drilling composite materials.

No other industry has attracted as much public attention to composite materials as the automotive industry, which along with the aerospace industry is a driver...

Im Focus: Room-temperature multiferroic thin films and their properties

Scientists at Tokyo Institute of Technology (Tokyo Tech) and Tohoku University have developed high-quality GFO epitaxial films and systematically investigated their ferroelectric and ferromagnetic properties. They also demonstrated the room-temperature magnetocapacitance effects of these GFO thin films.

Multiferroic materials show magnetically driven ferroelectricity. They are attracting increasing attention because of their fascinating properties such as...

Im Focus: A thermometer for the oceans

Measurement of noble gases in Antarctic ice cores

The oceans are the largest global heat reservoir. As a result of man-made global warming, the temperature in the global climate system increases; around 90% of...

Im Focus: Autoimmune Reaction Successfully Halted in Early Stage Islet Autoimmunity

Scientists at Helmholtz Zentrum München have discovered a mechanism that amplifies the autoimmune reaction in an early stage of pancreatic islet autoimmunity prior to the progression to clinical type 1 diabetes. If the researchers blocked the corresponding molecules, the immune system was significantly less active. The study was conducted under the auspices of the German Center for Diabetes Research (DZD) and was published in the journal ‘Science Translational Medicine’.

Type 1 diabetes is the most common metabolic disease in childhood and adolescence. In this disease, the body's own immune system attacks and destroys the...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Fachtagung analytica conference 2018

15.01.2018 | Event News

10th International Symposium: “Advanced Battery Power – Kraftwerk Batterie” Münster, 10-11 April 2018

08.01.2018 | Event News

See, understand and experience the work of the future

11.12.2017 | Event News

 
Latest News

Black hole spin cranks-up radio volume

15.01.2018 | Physics and Astronomy

A matter of mobility: multidisciplinary paper suggests new strategy for drug discovery

15.01.2018 | Life Sciences

New method to map miniature brain circuits

15.01.2018 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>