Featured Research

from universities, journals, and other organizations

Code-Breaking Insects Steal Plants' Defensive Signals, Enabling Counterattack

Date:
October 17, 2002
Source:
University Of Illinois At Urbana-Champaign
Summary:
Herbivorous insects that dine on crops use a form of molecular code-breaking to ready their defenses against a chemically protective shield employed by their dinner, say scientists at the University of Illinois at Urbana-Champaign.

CHAMPAIGN, Ill. -- Herbivorous insects that dine on crops use a form of molecular code-breaking to ready their defenses against a chemically protective shield employed by their dinner, say scientists at the University of Illinois at Urbana-Champaign.

Related Articles


Reporting in the Oct. 17 issue of the journal Nature, the researchers detailed how corn earworms (Helicoverpa zea) intercept defensive chemical signaling used by their hosts and then produce detoxifying agents to partially counter the threat against them.

"It's a cloak-and-dagger world out there in the fields," said co-author May Berenbaum, the head of the entomology department at Illinois.

When insects attack, many plants activate a cascading signal of jasmonate or salicylate, molecules that promote biosynthesis of toxic allelochemicals that can act both as poisons for herbivores and as attractants for natural enemies of the insects. By recognizing the signaling molecules, earworm caterpillars produce detoxifying enzymes, including cytochrome P450 proteins similar to those in the human liver that neutralize toxins.

"Jasmonic acid to the plant is like a Paul Revere running around shouting, "The British are coming, the British are coming," getting everybody in Boston to grab guns and call for reinforcements," Berenbaum said. "With this early warning signal, the caterpillars can activate their detox systems ahead of time for whatever the plant mobilizes."

In a series of experiments, entomology doctoral student Xianchun Li fed experimental diets containing jasmonate and salicylate to fifth instars -- the oldest caterpillar stage that causes the largest amount of crop damage. Examining the midgut and fatbody, where detoxifying chemicals are produced, Li found almost eightfold increases of P450 compared with caterpillars fed a control diet. At least one of the induced P450s is known to mediate the breakdown of specific toxins turned on in the plant by jasmonate.

The researchers found that the earwormsΥ ability to mount its own defenses begins with exposure to very low levels of jasmonate and salicylate. The exposure of earlier stage caterpillars to the molecules also triggers a response before they begin feasting. Exposure at the penultimate larval stage to these signaling molecules prepares the ultimate larval stage to handle elevated amounts of defense compounds produced by the plant in response to insect damage.

"Our data provide direct evidence that H. zea can intercept the plant defense signals elicited by its own feeding activity," the researchers wrote. Additionally, they noted, "the signal-eavesdropping capability provides H. zea with prophylactic protection against plant defenses at no additional cost to fitness in the absence of plant defenses."

There has been a lot of attention focused on how plants anticipate what insects are going to do, Berenbaum said. "This study shows that plants may have won some battles but the outcome of the war has not been determined. It's really an ongoing interaction."

The findings may have implications for pest-control strategies for the some 100 different plants the earworms feed on. Some researchers at other universities have proposed spraying plants with jasmonic acid to turn on plant defense systems before insects damage them. University of California researchers recently found that spraying the chemical on tomato plants indeed increased parasitism of beet army worms, prompting the idea that such a practice could reduce crop losses.

"Pouring on jasmonic acid might not be ideal under some circumstances, if it turns out that jasmonic acid also cranks up insect detoxification systems," Berenbaum said.

The research by was done under the supervision of Berenbaum and Mary A. Schuler, a professor in the department of cell and structural biology, with funding through grants from the U.S. Department of Agriculture.


Story Source:

The above story is based on materials provided by University Of Illinois At Urbana-Champaign. Note: Materials may be edited for content and length.


Cite This Page:

University Of Illinois At Urbana-Champaign. "Code-Breaking Insects Steal Plants' Defensive Signals, Enabling Counterattack." ScienceDaily. ScienceDaily, 17 October 2002. <www.sciencedaily.com/releases/2002/10/021017065807.htm>.
University Of Illinois At Urbana-Champaign. (2002, October 17). Code-Breaking Insects Steal Plants' Defensive Signals, Enabling Counterattack. ScienceDaily. Retrieved October 31, 2014 from www.sciencedaily.com/releases/2002/10/021017065807.htm
University Of Illinois At Urbana-Champaign. "Code-Breaking Insects Steal Plants' Defensive Signals, Enabling Counterattack." ScienceDaily. www.sciencedaily.com/releases/2002/10/021017065807.htm (accessed October 31, 2014).

Share This



More Plants & Animals News

Friday, October 31, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

How A Chorus Led Scientists To A New Frog Species

How A Chorus Led Scientists To A New Frog Species

Newsy (Oct. 30, 2014) — A frog noticed by a conservationist on New York's Staten Island has been confirmed as a new species after extensive study and genetic testing. Video provided by Newsy
Powered by NewsLook.com
Surfer Accidentally Stands on Shark, Gets Bitten

Surfer Accidentally Stands on Shark, Gets Bitten

AP (Oct. 30, 2014) — A 20-year-old competition surfer said on Thursday he accidentally stepped on a shark's head before it bit him off the Australian east coast. (Oct. 30) Video provided by AP
Powered by NewsLook.com
Ebola Inflicts Heavy Toll on Guinean Potato Trade

Ebola Inflicts Heavy Toll on Guinean Potato Trade

AFP (Oct. 30, 2014) — The Ebola epidemic has seen Senegal and Guinea Bissau close its borders with Guinea and the economic consequences have started to be felt, especially in Fouta Djallon, where the renowned potato industry has been hit hard. Duration: 02:01 Video provided by AFP
Powered by NewsLook.com
Genetically Altered Glowing Flower on Display in Tokyo

Genetically Altered Glowing Flower on Display in Tokyo

Reuters - Innovations Video Online (Oct. 30, 2014) — Just in time for Halloween, a glowing flower goes on display in Tokyo. Instead of sorcery and magic, its creators used science to genetically modify the flower, adding a naturally fluorescent plankton protein to its genetic mix. Ben Gruber reports. Video provided by Reuters
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