Featured Research

from universities, journals, and other organizations

New bacteria toxins against resistant insect pests

Date:
October 20, 2011
Source:
Max-Planck-Gesellschaft
Summary:
Scientists have developed Bt toxins for the management of Bt resistance in European corn borer and other crop pests.

Tobacco budworm (Heliothis virescens).
Credit: © Melanie Marr, MPI for Chemical Ecology

Toxins from Bacillus thuringiensis bacteria (Bt toxins) are used in organic and conventional farming to manage pest insects. Sprayed as pesticides or produced in genetically modified plants, Bt toxins, used in pest control since 1938, minimize herbivory in crops, such as vegetables, maize or cotton. Since 1996, Bt producing transgenic crops have been grown, which successfully control pests like the European corn borer, the tobacco budworm, the Western corn rootworm, and the cotton bollworm. Over the years, Bt resistant insects have emerged in organic and conventional farming.

Scientists have therefore modified the molecular structure of two Bt toxins, Cry1Ab and Cry1Ac, in order to overcome resistance. The novel toxins, Cry1AbMod and Cry1AcMod, are effective against five resistant insect species, such as the diamondback moth, the cotton bollworm, and the European corn borer. Cry1AbMod and Cry1AcMod can be used alone or in combination with other Bt toxins for plant protection.

New insights into the mechanisms of action of Cry1Ab and Cry1Ac served as the basis for development of the modified Bt toxins. The primary question had been why the Cry proteins, which naturally occur in B. thuringiensis, have such a resoundingly toxic effect on many different herbivorous insects. Researchers had previously found a protein in the caterpillars' midgut that binds Bt toxins -- with fateful consequences for the insects, because binding the toxins causes the gut cells to die. This protein is one of the many types of cadherin proteins in the cell. Mutations of a specific cadherin can make the caterpillars resistant against the toxins.

"When we studied the new Bt toxins in twelve resistant and non-resistant strains of five major pest species, the results of our experiments were encouraging but surprising. The new toxins are also effective against strains whose Bt resistance is not based on cadherin mutations," says David G. Heckel, director of the Department of Entomology at the Max Planck Institute for Chemical Ecology in Jena, Germany, and co-author of the study. Especially interesting was the finding that the new toxins were specifically effective against a super-resistant strain of tobacco budworm carrying both the cadherin mutation and another mutation affecting an ABC transporter which was discovered by the Max Planck researchers last year.

Particularly striking was the effect of Cry1AbMod and Cry1AcMod on a Bt resistant corn borer and a resistant diamondback moth strain that was 350 times stronger compared to that of the natural toxins. On the other hand, the new toxins had only a weak effect on some strains whose Bt resistance is due to a mutated cadherin.

If both novel Bt toxins prove to be useful in agriculture, they can be used in combination with different Bt toxins to guarantee a reliable effect on herbivorous pests. Biologists also agree that measures to reduce the occurrence of resistant insect pests must be strictly adhered to and that farmers should be informed in detail. Such measures would mainly include the use of different pesticides, crop rotation, and simultaneous sowing of non-Bt plants in fields, where transgenic Bt varieties are grown.


Story Source:

The above story is based on materials provided by Max-Planck-Gesellschaft. Note: Materials may be edited for content and length.


Journal Reference:

  1. Bruce E Tabashnik, Fangneng Huang, Mukti N Ghimire, B Rogers Leonard, Blair D Siegfried, Murugesan Rangasamy, Yajun Yang, Yidong Wu, Linda J Gahan, David G Heckel, Alejandra Bravo, Mario Soberσn. Efficacy of genetically modified Bt toxins against insects with different genetic mechanisms of resistance. Nature Biotechnology, 2011; DOI: 10.1038/nbt.1988

Cite This Page:

Max-Planck-Gesellschaft. "New bacteria toxins against resistant insect pests." ScienceDaily. ScienceDaily, 20 October 2011. <www.sciencedaily.com/releases/2011/10/111020024712.htm>.
Max-Planck-Gesellschaft. (2011, October 20). New bacteria toxins against resistant insect pests. ScienceDaily. Retrieved October 20, 2014 from www.sciencedaily.com/releases/2011/10/111020024712.htm
Max-Planck-Gesellschaft. "New bacteria toxins against resistant insect pests." ScienceDaily. www.sciencedaily.com/releases/2011/10/111020024712.htm (accessed October 20, 2014).

Share This



More Plants & Animals News

Monday, October 20, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Hey, Doc! Sewage, Beer and Food Scraps Can Power Chevrolet’s Bi-Fuel Impala

Hey, Doc! Sewage, Beer and Food Scraps Can Power Chevrolet’s Bi-Fuel Impala

3BL Media (Oct. 20, 2014) — Hey, Doc! Sewage, Beer and Food Scraps Can Power Chevrolet’s Bi-fuel Impala Video provided by 3BL
Powered by NewsLook.com
Captive Dolphin Gives Birth

Captive Dolphin Gives Birth

Reuters - Light News Video Online (Oct. 20, 2014) — SeaWorld in San Diego welcomes a new bottlenose dolphin, the second calf for 13-year-old female, Sadie. Rough Cut. (no reporter narration). Video provided by Reuters
Powered by NewsLook.com
Another Study Suggests Viagra Is Good For The Heart

Another Study Suggests Viagra Is Good For The Heart

Newsy (Oct. 20, 2014) — An ingredient in erectile-dysfunction medications such as Viagra could improve heart function. Perhaps not surprising, given Viagra's history. Video provided by Newsy
Powered by NewsLook.com
White Rhino's Death In Kenya Means Just 6 Are Left

White Rhino's Death In Kenya Means Just 6 Are Left

Newsy (Oct. 20, 2014) — Suni, a rare northern white rhino at Ol Pejeta Conservancy, died Friday. This, as many media have pointed out, leaves people fearing extinction. Video provided by Newsy
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
 
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:  

Breaking News:

Strange & Offbeat Stories

 

Plants & Animals

Earth & Climate

Fossils & Ruins

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:  

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile iPhone Android Web
Follow Facebook Twitter Google+
Subscribe RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins