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 In focus: Peptides, the “little brothers and sisters” of proteins
12.11.2018 | Technische Universität Berlin

nachricht How to produce fluorescent nanoparticles for medical applications in a nuclear reactor
09.11.2018 | Institute of Organic Chemistry and Biochemistry of the Czech Academy of Sciences (IOCB Prague)

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 Leap Into Quantum Technology

Faster and secure data communication: This is the goal of a new joint project involving physicists from the University of Würzburg. The German Federal Ministry of Education and Research funds the project with 14.8 million euro.

In our digital world data security and secure communication are becoming more and more important. Quantum communication is a promising approach to achieve...

Im Focus: Research icebreaker Polarstern begins the Antarctic season

What does it look like below the ice shelf of the calved massive iceberg A68?

On Saturday, 10 November 2018, the research icebreaker Polarstern will leave its homeport of Bremerhaven, bound for Cape Town, South Africa.

Im Focus: Penn engineers develop ultrathin, ultralight 'nanocardboard'

When choosing materials to make something, trade-offs need to be made between a host of properties, such as thickness, stiffness and weight. Depending on the application in question, finding just the right balance is the difference between success and failure

Now, a team of Penn Engineers has demonstrated a new material they call "nanocardboard," an ultrathin equivalent of corrugated paper cardboard. A square...

Im Focus: Coping with errors in the quantum age

Physicists at ETH Zurich demonstrate how errors that occur during the manipulation of quantum system can be monitored and corrected on the fly

The field of quantum computation has seen tremendous progress in recent years. Bit by bit, quantum devices start to challenge conventional computers, at least...

Im Focus: Nanorobots propel through the eye

Scientists developed specially coated nanometer-sized vehicles that can be actively moved through dense tissue like the vitreous of the eye. So far, the transport of nano-vehicles has only been demonstrated in model systems or biological fluids, but not in real tissue. The work was published in the journal Science Advances and constitutes one step further towards nanorobots becoming minimally-invasive tools for precisely delivering medicine to where it is needed.

Researchers of the “Micro, Nano and Molecular Systems” Lab at the Max Planck Institute for Intelligent Systems in Stuttgart, together with an international...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

“3rd Conference on Laser Polishing – LaP 2018” Attracts International Experts and Users

09.11.2018 | Event News

On the brain’s ability to find the right direction

06.11.2018 | Event News

European Space Talks: Weltraumschrott – eine Gefahr für die Gesellschaft?

23.10.2018 | Event News

 
Latest News

In focus: Peptides, the “little brothers and sisters” of proteins

12.11.2018 | Life Sciences

Materials scientist creates fabric alternative to batteries for wearable devices

12.11.2018 | Materials Sciences

A two-atom quantum duet

12.11.2018 | Physics and Astronomy

VideoLinks
Science & Research
Overview of more VideoLinks >>>