Featured Research

from universities, journals, and other organizations

Purdue Scientists Finding Ways To Outsmart Crop-damaging Bugs

Date:
April 13, 2004
Source:
Purdue University
Summary:
A new screening method aimed at boosting pesticide effectiveness may be commercially viable, according to Purdue University researchers.

WEST LAFAYETTE, Ind. - A new screening method aimed at boosting pesticide effectiveness may be commercially viable, according to Purdue University researchers.

The process is designed to identify chemical compounds that could be added to current pesticides to overcome resistance insects have developed to them. In a recent issue of the journal Pesticide Biochemistry & Physiology, the scientists report that the method will be applicable to a variety of insects and chemicals.

"It's becoming more and more difficult to find new, effective pesticides," said Barry Pittendrigh, assistant professor of entomology and senior author of the study. "If we can kill these pesticide-resistant insects in the field, then we have the potential to increase the functional life of the insecticides currently in use."

Crop-damaging insects mutate over time so they are able to overcome the effects of chemicals developed to kill them. A toxin that protected a crop for more than a decade or two eventually may lose its lethality due to resistance in the insect population.

According to the U.S. Department of Agriculture, more than $7.5 billion is spent annually on agricultural pesticides. This is about 30 percent to 50 percent of the variable costs involved in managing harmful insects.

Pittendrigh and his research team studied common research fruit flies, Drosophila melanogaster, in which the molecular mechanism that provides the insect with chemical resistance was known. They applied that knowledge to test known chemicals' toxicity to the resistant insects.

A pesticide's toxic effect occurs when a molecule on an insect's cells, called a receptor, acts as a loading dock for molecules in the pesticide. When a toxic chemical is used, its docking molecule, called a ligand, joins the receptor and kills the bug.

But nature allows pests to challenge control methods by altering their own receptors. These biochemical changes prevent binding of the chemical to the receptor and its entry into the bugs' system. Once this occurs, the chemical becomes ineffective and a new way to stop the insects is needed.

Discovery of other toxins to attack insects that have the altered receptor offers a new way of minimizing resistance in the insect population, Pittendrigh said. The newly introduced insecticide provides negative cross-resistance, meaning the chemicals react with the mutated molecule.

"Insects have a tremendous capacity to adapt to chemicals that we use to control them," Pittendrigh said. "That's just evolution in motion. With negative cross-resistance, we're buying time for the commercial life of another pesticide. Using resistance-breaking compounds is a way to potentially double or triple the time that the original compound is effective."

In this study, the researchers tested nine related insecticides in order to identify a negative cross-resistance toxin. They found that the resistant flies were highly susceptible to one compound called deltamethrin. Use of deltamethrin dramatically reduced the numbers of pesticide-resistant insects in a fruit fly population.

The researchers used DDT (dichlorodiphenyltrichloroethane) as their base chemical because they know the insect molecule with which it reacts. This gave them insight into how other chemicals would behave.

After finding that deltamethrin was the most effective, they added the DDT. Then they tested the combined toxicity.

Though it's banned in developed countries, DDT is commonly used for mosquito control in Third World countries where malaria is still the No. 1 killer.

"In the fly line, we have a known mechanism of resistance, and we understand how DDT works at the molecular level," Pittendrigh said. "So then we can describe and understand molecularly how negative cross-resistance occurs. DDT was used simply because it allowed us to test a model system."

One argument against negative cross-resistance has been that it will be difficult, if not impossible, to find compounds toxic to mutated insects, Pittendrigh said. However, this study shows it may not be as difficult to identify negative cross-resistance compounds as once assumed.

The screening process will speed up and simplify identifying effective compounds and add another weapon in the arsenal to fight crop-destroying insects.

"If we can extend the commercial lifetime of a current pesticide with a negative cross-resistance compound, that's the best we can hope for," Pittendrigh said.

The screening system for identifying negative cross-resistance compounds has the potential to be applicable to other insects and to be produced and used at a commercial level, he said. But first, the molecular evolution of pesticide resistance in each targeted insect must be known.

For the negative cross-resistance toxin to be beneficial and financially viable, it would have to be used in cases where the evolutionary change in the target insect is seen in more than one line of the bug, which is found across a wide geographical area, Pittendrigh said. The chance of successful use of a chemical is even better if this resistance mechanism is the same across a wide variety of pest insects.

The other researchers involved in this study were: Joao Pedra and Andrew Hostetler, a doctoral student and a researcher assistant, respectively, in Purdue's Department of Entomology; Patrick Gaffney, University of Wisconsin, Madison, Department of Statistics; and Robert Reenan, associate professor, University of Connecticut Department of Genetics and Developmental Biology. Pedra and Pittendrigh also are part of the Purdue Molecular Plant Resistance and Nematode Team.

The Purdue Department of Entomology provided funding for this research.

Related Web sites:

Purdue Department of Entomology: http://www.entm.purdue.edu/

Environmental Protection Agency, DDT History: http://www.epa.gov/history/topics/ddt/01.htm

Pesticide Biochemistry & Physiology: http://authors.elsevier.com/JournalDetail.html?PubID=622930&Precis=DESC


Story Source:

The above story is based on materials provided by Purdue University. Note: Materials may be edited for content and length.


Cite This Page:

Purdue University. "Purdue Scientists Finding Ways To Outsmart Crop-damaging Bugs." ScienceDaily. ScienceDaily, 13 April 2004. <www.sciencedaily.com/releases/2004/04/040412235824.htm>.
Purdue University. (2004, April 13). Purdue Scientists Finding Ways To Outsmart Crop-damaging Bugs. ScienceDaily. Retrieved July 31, 2014 from www.sciencedaily.com/releases/2004/04/040412235824.htm
Purdue University. "Purdue Scientists Finding Ways To Outsmart Crop-damaging Bugs." ScienceDaily. www.sciencedaily.com/releases/2004/04/040412235824.htm (accessed July 31, 2014).

Share This




More Plants & Animals News

Thursday, July 31, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Visitors Feel Part of the Pack at Wolf Preserve

Visitors Feel Part of the Pack at Wolf Preserve

AP (July 31, 2014) — Seacrest Wolf Preserve on the northern Florida panhandle allows more than 10,000 visitors each year to get up close and personal with Arctic and British Columbian Wolves. (July 31) Video provided by AP
Powered by NewsLook.com
Florida Panther Rebound Upsets Ranchers

Florida Panther Rebound Upsets Ranchers

AP (July 31, 2014) — With Florida's panther population rebounding, some ranchers complain the protected predators are once again killing their calves. (July 31) Video provided by AP
Powered by NewsLook.com
Dangerous Bacteria Kills One in Florida

Dangerous Bacteria Kills One in Florida

AP (July 31, 2014) — Sarasota County, Florida health officials have issued a warning against eating raw oysters and exposing open wounds to coastal and inland waters after a dangerous bacteria killed one person and made another sick. (July 31) Video provided by AP
Powered by NewsLook.com
Raw: Thousands Flocking to German Crop Circle

Raw: Thousands Flocking to German Crop Circle

AP (July 30, 2014) — Thousands of people are trekking to a Bavarian farmer's field to check out a mysterious set of crop circles. (July 30) Video provided by AP
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:
from the past week

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