. Energy News .

New bacteria toxins against resistant insect pests
by Staff Writers
Jena, Germany (SPX) Oct 24, 2011

Tobacco budworm (Heliothis virescens). Image courtesy 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.

Related Links
Max Planck Institute for Chemical Ecology
Farming Today - Suppliers and Technology

Get Our Free Newsletters Via Email
Buy Advertising Editorial Enquiries


. Comment on this article via your Facebook, Yahoo, AOL, Hotmail login.

Share this article via these popular social media networks
del.icio.usdel.icio.us DiggDigg RedditReddit GoogleGoogle

Study Reveals Diversity of Life in Soils
Washington DC (SPX) Oct 24, 2011
Microscopic animals that live in soils are as diverse in the tropical forests of Costa Rica as they are in the arid grasslands of Kenya, or the tundra and boreal forests of Alaska and Sweden. That conclusion is found in research results published in the journal Proceedings of the National Academy of Sciences. Scientists have generally accepted that a wider range of species can be found abo ... read more

Better use of Global Geospatial Information for Solving Development Challenges

NASA postpones climate satellite launch to Oct 28

NASA Readies New Type of Earth-Observing Satellite for Launch

NASA, Japan Release Improved Topographic Map of Earth

GIS Technology Plays Critical Role to Aid Joplin Tornado Survivors

Russia surprised as Apple uses Glonass in new iPhone

Galileo - keeping time with atomic clocks

Factfile on Galileo, Europe's rival to GPS

Bolivia reaches agreement with Amazon protesters

Bolivia natives, president in talks stand-off

Bolivia cancels controversial Amazon highway

"Albedo effect" in forests can cause added warming, bonus cooling

Global Biofuels Market Value to Double by 2021

FuturaGene and Guangxi Academy of Sciences to Develop Sustainable Biofuel Processes

MixAlco Voted Most Transformative Technology of 2011

Codexis and Raizen to Develop First Generation Ethanol

PHAT Energy Releases Sunpower Version Of The Successful PHATport

SunConnect Signs Agreement with Macy's To Develop Roof-Mounted PV System

US Solar Jobs Census Finds Solar Employment Soars As US Economy Lags

GE Energy and Inovateus Solar Partner on Solar Carport Charging Stations

Vestas receives 99MW order for Texas wind-energy project

GE invests in Indian wind power

Euro Bank: Wind policy 'direction' needed

Natural Power US to act as Owner's Engineer on 2.1GW Wyoming wind farm

Thirteen dead in China coal mine blast: report

Sundance says 'no reason' to doubt Hanlong deal

Mountaintop coal mining moves a step ahead

13 killed in China mine explosion

China's local election candidates campaign online

Hong Kong mothers march against mainland babies

Chinese hit and run toddler dies

Immolations spark fear in China's Tibetan Buddhists


The content herein, unless otherwise known to be public domain, are Copyright 1995-2011 - Space Media Network. AFP and UPI Wire Stories are copyright Agence France-Presse and United Press International. ESA Portal Reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. Advertising does not imply endorsement,agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. Privacy Statement