Navigation Links
First documented case of pest resistance to biotech cotton
Date:2/7/2008

A pest insect known as bollworm is the first to evolve resistance in the field to plants modified to produce an insecticide called Bt, according to a new research report.

Bt-resistant populations of bollworm, Helicoverpa zea, were found in more than a dozen crop fields in Mississippi and Arkansas between 2003 and 2006.

"What we're seeing is evolution in action," said lead researcher Bruce Tabashnik. "This is the first documented case of field-evolved resistance to a Bt crop.

Bt crops are so named because they have been genetically altered to produce Bt toxins, which kill some insects. The toxins are produced in nature by the widespread bacterium Bacillus thuringiensis, hence the abbreviation Bt.

The bollworm resistance to Bt cotton was discovered when a team of University of Arizona entomologists analyzed published data from monitoring studies of six major caterpillar pests of Bt crops in Australia, China, Spain and the U.S. The data documenting bollworm resistance were first collected seven years after Bt cotton was introduced in 1996.

"Resistance is a decrease in pest susceptibility that can be measured over human experience," said Tabashnik, professor and head of UA's entomology department and an expert in insect resistance to insecticides. "When you use an insecticide to control a pest, some populations eventually evolves resistance."

The researchers write in their report that Bt cotton and Bt corn have been grown on more than 162 million hectares (400 million acres) worldwide since 1996, generating one of the largest selections for insect resistance ever known."

Even so, the researchers found that most caterpillar pests of cotton and corn remained susceptible to Bt crops.

"The resistance occurred in one particular pest in one part of the U.S.," Tabashnik said. "The other major pests attacking Bt crops have not evolved resistance. And even most bollworm populations have not evolved resistance."

The field outcomes refute some experts' worst-case scenarios that predicted pests would become resistant to Bt crops in as few as three years, he said.

The only other case of field-evolved resistance to Bt toxins involves resistance to Bt sprays," Tabashnik said. He added that such sprays have been used for decades, but now represent a small proportion of the Bt used against crop pests.

The bollworm is a major cotton pest in the southeastern U.S. and Texas, but not in Arizona. The major caterpillar pest of cotton in Arizona is a different species known as pink bollworm, Pectinophora gossypiella, which has remained susceptible to the Bt toxin in biotech cotton.

Tabashnik and his colleagues' article, "Insect resistance to Bt crops: evidence versus theory," will be published in the February issue of Nature Biotechnology. His co-authors are Aaron J. Gassmann, a former UA postdoctoral fellow now an assistant professor at Iowa State University; David W. Crowder, a UA doctoral student; and Yves Carrire, a UA professor of entomology. Tabashnik and Carrire are members of UA's BIO5 Institute.

The U.S. Department of Agriculture funded the research.

"Our research shows that in Arizona, Bt cotton reduces use of broad-spectrum insecticides and increases yield," said Carrire. Such insecticides kill both pest insects and beneficial insects.

To delay resistance, non-Bt crops are planted near Bt crops to provide "refuges" for susceptible pests. Because resistant insects are rare, the only mates they are likely to encounter would be susceptible insects from the refuges. The hybrid offspring of such a mating generally would be susceptible to the toxin. In most pests, offspring are resistant to Bt toxins only if both parents are resistant.

In bollworm, however, hybrid offspring produced by matings between susceptible and resistant moths are resistant. Such a dominant inheritance of resistance was predicted to make resistance evolve faster.

The UA researchers found that bollworm resistance evolved fastest in the states with the lowest abundance of refuges.

The field outcomes documented by the global monitoring data fit the predictions of the theory underlying the refuge strategy, Tabashnik said.

Although first-generation biotech cotton contained only one Bt toxin called Cry1Ac, a new variety contains both Cry1Ac and a second Bt toxin, Cry2Ab. The combination overcomes pests that are resistant to just one toxin.

The next steps, Tabashnik said, include conducting research to understand inheritance of resistance to Cry2Ab and developing designer toxins to kill pests resistant to Cry1Ac.


'/>"/>

Contact: Mari N. Jensen
mnjensen@email.arizona.edu
520-626-9635
University of Arizona
Source:Eurekalert  

Related biology technology :

1. Tutogen Medical, Inc. Reports First Quarter Fiscal 2008 Financial Results
2. Rochester Medical Reports 31% Increase in Branded Sales Resulting in 9% Overall Sales Growth for the First Quarter
3. Johns Hopkins Bayview at Forefront of Expanding Access to MRI With First Install of Siemens New MAGNETOM Verio
4. Eisai/Pfizers Aricept Owns a Dominating 42.4% Patient Share for First-Line Treatment of Alzheimers Disease
5. Hologic Announces First Quarter Fiscal 2008 Operating Results
6. Topspin Medical Announces First Commercial Installation of the Cathamaran(TM) Intravascular MRI System
7. Cascade Microtech Introduces Worlds First 45 nm-capable DC/RF Parametric Probe Card Solutions, Lowers Cost of Ownership
8. RG Global Corporate Update: First Coal Bed Methane Water Treatment Plant Near Completion; Expanding Water Treatment Applications
9. Cellix Ltd. Launches the First Semi-Automated, High Throughput Cell-Adhesion Assay Platform
10. The Dark Report and Siemens Introduce the Worlds First Integrated Molecular Summit
11. Hologic, Inc. to Release First Quarter Fiscal 2008 Operating Results Thursday, January 31st Before Market Opens
Post Your Comments:
*Name:
*Comment:
*Email:
Related Image:
First documented case of pest resistance to biotech cotton
(Date:6/23/2016)... , June 23, 2016   EpiBiome , ... secured $1 million in debt financing from Silicon Valley ... up automation and to advance its drug development efforts, ... new facility. "SVB has been an incredible ... the services a traditional bank would provide," said Dr. ...
(Date:6/23/2016)... 23, 2016 Apellis Pharmaceuticals, Inc. today ... trials of its complement C3 inhibitor, APL-2. The ... ascending dose studies designed to assess the safety, ... injection in healthy adult volunteers. Forty ... a single dose (ranging from 45 to 1,440mg) ...
(Date:6/23/2016)... ... June 23, 2016 , ... ... at the Pennsylvania Convention Center and will showcase its product’s latest features from ... also be presenting a scientific poster on Disrupting Clinical Trials in The Cloud ...
(Date:6/23/2016)... 2016 ReportsnReports.com adds 2016 ... its pharmaceuticals section with historic and forecast data ... more. Complete report on the Cell ... 15 companies and supported with 261 tables and ... . The Global Cell Culture Media ...
Breaking Biology Technology:
(Date:5/24/2016)... care by providing unparalleled technology to leaders of the medical imaging industry.  As such, ... to the range of products distributed by Ampronix. Photo - http://photos.prnewswire.com/prnh/20160524/371420 ... ... ... With ...
(Date:5/3/2016)... May 3, 2016  Neurotechnology, a provider of ... MegaMatcher Automated Biometric Identification System (ABIS) , a ... projects. MegaMatcher ABIS can process multiple complex biometric ... combination of fingerprint, face or iris biometrics. It ... and MegaMatcher Accelerator , which have ...
(Date:4/19/2016)... UAE, April 20, 2016 The ... as a compact web-based "all-in-one" system solution for all ... fingerprint reader or the door interface with integration authorization ... access control systems. The minimal dimensions of the access ... into the building installations offer considerable freedom of design ...
Breaking Biology News(10 mins):