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 Flavins keep a handy helper in their pocket
25.04.2018 | University of Freiburg

nachricht Complete skin regeneration system of fish unraveled
24.04.2018 | Tokyo Institute of Technology

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: BAM@Hannover Messe: innovative 3D printing method for space flight

At the Hannover Messe 2018, the Bundesanstalt für Materialforschung und-prüfung (BAM) will show how, in the future, astronauts could produce their own tools or spare parts in zero gravity using 3D printing. This will reduce, weight and transport costs for space missions. Visitors can experience the innovative additive manufacturing process live at the fair.

Powder-based additive manufacturing in zero gravity is the name of the project in which a component is produced by applying metallic powder layers and then...

Im Focus: Molecules Brilliantly Illuminated

Physicists at the Laboratory for Attosecond Physics, which is jointly run by Ludwig-Maximilians-Universität and the Max Planck Institute of Quantum Optics, have developed a high-power laser system that generates ultrashort pulses of light covering a large share of the mid-infrared spectrum. The researchers envisage a wide range of applications for the technology – in the early diagnosis of cancer, for instance.

Molecules are the building blocks of life. Like all other organisms, we are made of them. They control our biorhythm, and they can also reflect our state of...

Im Focus: Spider silk key to new bone-fixing composite

University of Connecticut researchers have created a biodegradable composite made of silk fibers that can be used to repair broken load-bearing bones without the complications sometimes presented by other materials.

Repairing major load-bearing bones such as those in the leg can be a long and uncomfortable process.

Im Focus: Writing and deleting magnets with lasers

Study published in the journal ACS Applied Materials & Interfaces is the outcome of an international effort that included teams from Dresden and Berlin in Germany, and the US.

Scientists at the Helmholtz-Zentrum Dresden-Rossendorf (HZDR) together with colleagues from the Helmholtz-Zentrum Berlin (HZB) and the University of Virginia...

Im Focus: Gamma-ray flashes from plasma filaments

Novel highly efficient and brilliant gamma-ray source: Based on model calculations, physicists of the Max PIanck Institute for Nuclear Physics in Heidelberg propose a novel method for an efficient high-brilliance gamma-ray source. A giant collimated gamma-ray pulse is generated from the interaction of a dense ultra-relativistic electron beam with a thin solid conductor. Energetic gamma-rays are copiously produced as the electron beam splits into filaments while propagating across the conductor. The resulting gamma-ray energy and flux enable novel experiments in nuclear and fundamental physics.

The typical wavelength of light interacting with an object of the microcosm scales with the size of this object. For atoms, this ranges from visible light to...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Invitation to the upcoming "Current Topics in Bioinformatics: Big Data in Genomics and Medicine"

13.04.2018 | Event News

Unique scope of UV LED technologies and applications presented in Berlin: ICULTA-2018

12.04.2018 | Event News

IWOLIA: A conference bringing together German Industrie 4.0 and French Industrie du Futur

09.04.2018 | Event News

 
Latest News

Getting electrons to move in a semiconductor

25.04.2018 | Physics and Astronomy

Reconstructing what makes us tick

25.04.2018 | Physics and Astronomy

Cheap 3-D printer can produce self-folding materials

25.04.2018 | Information Technology

VideoLinks
Science & Research
Overview of more VideoLinks >>>