Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:


Scientists Discover Genetic Basis of Pest Resistance to Biotech Cotton


An international team led by scientists at the University of Arizona and the U.S. Department of Agriculture has discovered what happens on a molecular basis in insects that evolved resistance to genetically engineered cotton plants.

The findings, reported in the May 19 issue of the journal PLOS ONE, shed light on how the global caterpillar pest called pink bollworm overcomes biotech cotton, which was designed to make an insect-killing bacterial protein called Bt toxin.  The results could have major impacts for managing pest resistance to Bt crops. 

"Bt crops have had major benefits for society," said Jeffrey Fabrick, the lead author of the study and a research entomologist at the USDA Agricultural Research Service in Maricopa, Arizona. "By understanding how insects adapt to Bt crops we can devise better strategies to delay the evolution of resistance and extend these benefits." 

"Many mechanisms of resistance to Bt proteins have been proposed and studied in the lab, but this is the first analysis of the molecular genetic basis of severe pest resistance to a Bt crop in the field," said Bruce Tabashnik, one of the paper's authors and the head of the Department of Entomology in the UA College of Agriculture and Life Sciences. He also is a member of the UA's BIO5 Institute. 

Based on laboratory experiments aimed at determining the molecular mechanisms involved, scientists knew that pink bollworm could evolve resistance against the Bt toxin, but they had to go all the way to India to observe this happening in the field.

Farmers in the U.S., but not in India, adopted tactics designed to slow evolution of resistance in pink bollworm. Scientists from the UA and the USDA worked closely with cotton growers in Arizona to develop and implement resistance management strategies such as providing "refuges" of standard cotton plants that do not produce Bt proteins and releasing sterile pink bollworm moths. Planting refuges near Bt crops allows susceptible insects to survive and reproduce and thus reduces the chances that two resistant insects will mate with each other and produce resistant offspring. Similarly, mass release of sterile moths also makes it less likely for two resistant individuals to encounter each other and mate.

As a result, pink bollworm has been all but eradicated in the southwestern U.S.  Suppression of this pest with Bt cotton is the cornerstone of an integrated pest management program that has allowed Arizona cotton growers to reduce broad spectrum insecticide use by 80 percent, saving them over $10 million annually. 

In India, however, resistant pink bollworm populations have emerged. 

Crops genetically engineered to produce proteins from the bacterium Bacillus thuringiensis – or Bt – were introduced in 1996 and planted on more than 180 million acres worldwide during 2013. Organic growers have used Bt proteins in sprays for decades because they kill certain pests but are not toxic to people and most other organisms. Pest control with Bt proteins – either in sprays or genetically engineered crops – reduces reliance on chemical insecticides. Although Bt proteins provide environmental and economic benefits, these benefits are cut short when pests evolve resistance. 

By sequencing the DNA of resistant pink bollworm collected from the field in India – which grows the most Bt cotton of any country in the world – the team found that the insects produce remarkably diverse disrupted variants of a protein called cadherin. Mutations that disrupt cadherin prevent Bt toxin from binding to it, which leaves the insect unscathed by the Bt toxin. The researchers learned that the astonishing diversity of cadherin in pink bollworm from India is caused by alternative splicing, a novel mechanism of resistance that allows a single DNA sequence to code for many variants of a protein. 

"Our findings represent the first example of alternative splicing associated with Bt resistance that evolved in the field," said Fabrick, who is also an adjunct scientist in the Department of Entomology at the UA.  

Mario Soberón, a Bt expert at the Universidad Nacional Autónoma de México in Cuernavaca, who was not an author of the study, commented, "This is a neat example of the diverse mechanisms insect possess to evolve resistance. An important implication is that DNA screening would not be efficient for monitoring resistance of pink bollworm to Bt toxins."


Bruce Tabashnik

UA College of Agriculture and Life Sciences

Jeffrey Fabrick 

U.S. Department of Agriculture

UANews Contact 

Daniel Stolte



Research paper: 

UA College of Agriculture and Life Sciences:   

BIO5 Institute:

Daniel Stolte | University of Arizona

Further reports about: Arizona Biotech DNA Genetic Life Pest cadherin cotton crops evolve insects proteins resistance variants

More articles from Agricultural and Forestry Science:

nachricht Harnessing a peptide holds promise for increasing crop yields without more fertilizer
25.11.2015 | University of Massachusetts at Amherst

nachricht Study shows how crop prices and climate variables affect yield and acreage
18.11.2015 | University of Illinois College of Agricultural, Consumer and Environmental Sciences

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: Climate study finds evidence of global shift in the 1980s

Planet Earth experienced a global climate shift in the late 1980s on an unprecedented scale, fuelled by anthropogenic warming and a volcanic eruption, according to new research published this week.

Scientists say that a major step change, or ‘regime shift’, in the Earth’s biophysical systems, from the upper atmosphere to the depths of the ocean and from...

Im Focus: Innovative Photovoltaics – from the Lab to the Façade

Fraunhofer ISE Demonstrates New Cell and Module Technologies on its Outer Building Façade

The Fraunhofer Institute for Solar Energy Systems ISE has installed 70 photovoltaic modules on the outer façade of one of its lab buildings. The modules were...

Im Focus: Lactate for Brain Energy

Nerve cells cover their high energy demand with glucose and lactate. Scientists of the University of Zurich now provide new support for this. They show for the first time in the intact mouse brain evidence for an exchange of lactate between different brain cells. With this study they were able to confirm a 20-year old hypothesis.

In comparison to other organs, the human brain has the highest energy requirements. The supply of energy for nerve cells and the particular role of lactic acid...

Im Focus: Laser process simulation available as app for first time

In laser material processing, the simulation of processes has made great strides over the past few years. Today, the software can predict relatively well what will happen on the workpiece. Unfortunately, it is also highly complex and requires a lot of computing time. Thanks to clever simplification, experts from Fraunhofer ILT are now able to offer the first-ever simulation software that calculates processes in real time and also runs on tablet computers and smartphones. The fast software enables users to do without expensive experiments and to find optimum process parameters even more effectively.

Before now, the reliable simulation of laser processes was a job for experts. Armed with sophisticated software packages and after many hours on computer...

Im Focus: Quantum Simulation: A Better Understanding of Magnetism

Heidelberg physicists use ultracold atoms to imitate the behaviour of electrons in a solid

Researchers at Heidelberg University have devised a new way to study the phenomenon of magnetism. Using ultracold atoms at near absolute zero, they prepared a...

All Focus news of the innovation-report >>>



Event News

Fraunhofer’s Urban Futures Conference: 2 days in the city of the future

25.11.2015 | Event News

Gluten oder nicht Gluten? Überempfindlichkeit auf Weizen kann unterschiedliche Ursachen haben

17.11.2015 | Event News

Art Collection Deutsche Börse zeigt Ausstellung „Traces of Disorder“

21.10.2015 | Event News

Latest News

Siemens to supply 126 megawatts to onshore wind power plants in Scotland

27.11.2015 | Press release

Two decades of training students and experts in tracking infectious disease

27.11.2015 | Life Sciences

Coming to a monitor near you: A defect-free, molecule-thick film

27.11.2015 | Materials Sciences

More VideoLinks >>>