Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

New Designer Toxins Kill Bt-Resistant Insect Pests

02.11.2007
A new way to combat resistant pests stems from discovering how the widely used natural insecticide Bt kills insects.

Figuring out how Bt toxins punch holes in the cells of an insect's gut was the key to designing the new toxins, according to a Mexico-U.S. research team.

Some insects have developed resistance to Bt toxins, naturally occurring insecticides used worldwide to combat pests of crops such as cotton and corn and also disease-carrying mosquitoes. "This is the first time that knowledge of how Bt toxins work and how insects become resistant have been used to design toxins that kill resistant insects," said research team member Bruce Tabashnik of The University of Arizona in Tucson.

The discovery is important for cotton-growing areas such as northern Mexico, Texas and Arizona. More than 90 percent of Arizona's approximately 200,000 acres of cotton are planted in the biotech cotton known as Bt cotton. "Our goal is to control insects in environmentally friendly ways so we can limit the damage that insects do to crops and the harm they do to people by transmitting disease," said Tabashnik, head of the UA's entomology department and a member of the UA's BIO5 Institute.

... more about:
»Bravo »Sober »Tabashnik »UA' »cadherin »insect »insecticide »unam

"Bt toxins are great for that because they only kill certain insects and don't harm other living things. These new designer toxins give us another environmentally friendly way to control insects."

The Mexico team developed the designer toxins by tweaking the gene that codes for the toxin, a protein. The researchers then teamed up with Tabashnik to test their modified toxins on UA's colony of Bt-resistant pink bollworms, major cotton pests.

Team member Alejandra Bravo, a research scientist at Universidad Nacional Auton?ma de México (UNAM) said, "We proposed that changing a small part of the toxin would kill the insect -- and we did it."

The team's research article, "Engineering Modified Bt Toxins to Counter Insect Resistance," is scheduled for publication in Science Express, the online version of the journal Science, on Thursday, Nov. 1. A complete list of authors and funding agencies is at the bottom of this release.

The collaboration between the UNAM team of molecular biologists and the American expert in the evolution of pest resistance happened by accident.

Mario Sober?n and Alejandra Bravo, a husband-wife research team, had invited Tabashnik to give a talk in Cuernavaca, Mexico, at a scientific conference on pore-forming bacterial toxins such as Bt solution.

Tabashnik said, "While I was there, I got turista -- which is caused by pore-forming bacterial toxins. I was pretty sick."

The couple cared for Tabashnik while he recovered. He asked what he could do to repay their kindness, and Sober?n suggested collaborating to test their designer toxins on UA's resistant insects.

"It was the perfect match," Tabashnik said. "We knew what made our strains resistant, and they hypothesized that their designer toxins could overcome the resistance."

The discovery is based on understanding a receptor molecule called cadherin on the insects' gut membranes. Normal cadherin binds with the Bt toxin in a lock-and-key fashion.

After the toxin binds, an enzyme hacks a bit off each toxin molecule.

The trimmed toxin molecules clump and form pores in the gut membrane cells. The pores let materials flow chaotically in and out of the cells. As a result cells and ultimately the insect die.

Tabashnik and his UA colleagues Tim Dennehy and Yves Carrière knew the Bt-resistant pink bollworms in their colony had a mutant version of cadherin.

Tabashnik said, "These resistant insects have genetic changes, mutations, that change the lock. Their cadherin no longer takes the key."

The UNAM team did an end-run around the resistant insects' strategy. The modified, or designer, toxins have that crucial bit already gone, so they clump and form the death-dealing pores. No cadherin needed.

Bravo said, "When Bruce told us it killed the insects, we were very happy. We know if it kills resistant insects, it will be very important."

The researchers have applied for a multinational patent for the designer toxins.
UNAM is the lead organization in the patent.
Combating Bt-resistant pests without using broad-spectrum insecticides can make agriculture safer for farm workers, better for the environment and more profitable for growers, Tabashnik said.

He said, "The university research that helped produce this new invention is an investment that can bring returns to the state of Arizona.”

With the exception of Tabashnik, all the authors on the research paper are UNAM's Instituto de Biotecnolog?a in Cuernavaca, Morelos. Tabashnik's co-authors are Mario Sober?n, Liliana Pardo-L?pez, Idalia L?pez, Isabel G?mez and Alejandra Bravo.

The Mexican National Council of Science & Technology (Consejo Nacional de Cienca y Tecnolog?a, or CONACyT), the U.S. National Institutes of Health, and the U.S.

Department of Agriculture funded the research.

Researcher contact information:
Bruce Tabashnik, 520-621-1141
brucet@ag.arizona.edu
Mario Sober?n, 52-777-3291618
mario@ibt.unam.mx
Alejandra Bravo, 52-777-3291635
bravo@ibt.unam.mx
Related Web sites:
Bruce Tabashnik
http://ag.arizona.edu/ento/faculty/tabashnik.htm
Mario Sober?n
http://www.ibt.unam.mx/server/PRG.base?tipo:doc,dir:PRG.curriculum,par:mario
Alejandra Bravo
http://www.ibt.unam.mx/server/PRG.base?tipo:doc,dir:PRG.grupo,par:Gab,tit:_Grupo_de_la__Dra._Maria_Alejandra_Bravo

Mari Jensen | The University of Arizona
Further information:
http://www.bio5.org
http://uanews.org

Further reports about: Bravo Sober Tabashnik UA' cadherin insect insecticide unam

More articles from Life Sciences:

nachricht Transport of molecular motors into cilia
28.03.2017 | Aarhus University

nachricht Asian dust providing key nutrients for California's giant sequoias
28.03.2017 | University of California - Riverside

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: A Challenging European Research Project to Develop New Tiny Microscopes

The Institute of Semiconductor Technology and the Institute of Physical and Theoretical Chemistry, both members of the Laboratory for Emerging Nanometrology (LENA), at Technische Universität Braunschweig are partners in a new European research project entitled ChipScope, which aims to develop a completely new and extremely small optical microscope capable of observing the interior of living cells in real time. A consortium of 7 partners from 5 countries will tackle this issue with very ambitious objectives during a four-year research program.

To demonstrate the usefulness of this new scientific tool, at the end of the project the developed chip-sized microscope will be used to observe in real-time...

Im Focus: Giant Magnetic Fields in the Universe

Astronomers from Bonn and Tautenburg in Thuringia (Germany) used the 100-m radio telescope at Effelsberg to observe several galaxy clusters. At the edges of these large accumulations of dark matter, stellar systems (galaxies), hot gas, and charged particles, they found magnetic fields that are exceptionally ordered over distances of many million light years. This makes them the most extended magnetic fields in the universe known so far.

The results will be published on March 22 in the journal „Astronomy & Astrophysics“.

Galaxy clusters are the largest gravitationally bound structures in the universe. With a typical extent of about 10 million light years, i.e. 100 times the...

Im Focus: Tracing down linear ubiquitination

Researchers at the Goethe University Frankfurt, together with partners from the University of Tübingen in Germany and Queen Mary University as well as Francis Crick Institute from London (UK) have developed a novel technology to decipher the secret ubiquitin code.

Ubiquitin is a small protein that can be linked to other cellular proteins, thereby controlling and modulating their functions. The attachment occurs in many...

Im Focus: Perovskite edges can be tuned for optoelectronic performance

Layered 2D material improves efficiency for solar cells and LEDs

In the eternal search for next generation high-efficiency solar cells and LEDs, scientists at Los Alamos National Laboratory and their partners are creating...

Im Focus: Polymer-coated silicon nanosheets as alternative to graphene: A perfect team for nanoelectronics

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are less stable. Now researchers at the Technical University of Munich (TUM) have, for the first time ever, produced a composite material combining silicon nanosheets and a polymer that is both UV-resistant and easy to process. This brings the scientists a significant step closer to industrial applications like flexible displays and photosensors.

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

International Land Use Symposium ILUS 2017: Call for Abstracts and Registration open

20.03.2017 | Event News

CONNECT 2017: International congress on connective tissue

14.03.2017 | Event News

ICTM Conference: Turbine Construction between Big Data and Additive Manufacturing

07.03.2017 | Event News

 
Latest News

Researchers shoot for success with simulations of laser pulse-material interactions

29.03.2017 | Materials Sciences

Igniting a solar flare in the corona with lower-atmosphere kindling

29.03.2017 | Physics and Astronomy

As sea level rises, much of Honolulu and Waikiki vulnerable to groundwater inundation

29.03.2017 | Earth Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>