Featured Research

from universities, journals, and other organizations

The hungry caterpillar: Beware your enemy's enemy's enemy

Date:
November 27, 2012
Source:
Public Library of Science
Summary:
When herbivores such as caterpillars feed, plants may "call for help" by emitting volatiles, which can help defend the plants. The volatiles recruit parasitoids that infect and kill the herbivores, to the benefit of the plant. However, such plant odors can also be detected by other organisms. A new study shows how secondary parasitoids can use these signals to identify infected caterpillars, and duly infect the primary parasitoid, to the detriment of the original plant.

Lysibia nana parasitizing cocoons of Cotesia glomerata.
Credit: Nina Fatouros, www.bugsinthepicture.com

When herbivores such as caterpillars feed, plants may "call for help" by emitting volatiles, which can indirectly help defend the plants. The volatiles recruit parasitoids that infect, consume and kill the herbivores, to the benefit of the plant. However, such induced plant odours can also be detected by other organisms. A new study published Nov. 27 in the open access journal PLOS Biology shows how secondary parasitoids ('hyperparasitoids') can take advantage of these plant signals to identify parasitoid-infected caterpillars, and duly infect the primary parasitoid, to the detriment of the original plant.

Related Articles


Plant volatiles have long been considered to mediate this mutualistic relationship between plants and herbivores' natural enemies such as parasitoids. When a caterpillar feeds, the parasitoids are able to use the emitted volatiles to locate the otherwise inconspicuous caterpillar, releasing the plant from its attacker. This principle has made its way into sustainable agriculture by using natural enemies such as parasitoids to control herbivorous pests on agricultural crops. However, the largest group of enemies of parasitoids, hyperparasitoids, have so far been left out of studies in this area. This is because very little is known about the cues that hyperparasitoids use to locate their parasitoid hosts.

The new study, by a team of Dutch researchers led by Erik Poelman, shows that hyperparasitoids exploit the different plant odours that are released when a plant is fed upon by a parasitoid-infected caterpillar.

"In controlled laboratory assays as well as under field conditions, hyperparasitoids were offered plant odours coming from two types of plant: ones damaged by healthy caterpillars, and ones damaged by parasitoid-infected caterpillars. We found that they preferentially detected odours of plants damaged by infected caterpillars," explained Dr Poelman. "We were excited by these results as they indicate that hyperparasitoids rely on a network of interactions among plant, herbivore and parasitoids to locate their host."

To show how this complex network of interactions can reliably provide hyperparasitoids with information on the presence of their parasitoid host, the researchers collected saliva of the caterpillars, as they noticed the colour of saliva in healthy, non-host caterpillars was different to that of caterpillars hosting a parasitoid. Factors in caterpillar saliva play an important role in provoking the release of odours from plants, and a change in saliva composition may then alter the cocktail of odours emitted by the plant.

Indeed, Dr Poelman's team found that plant odours induced by the saliva of parasitized caterpillars was more attractive to hyperparasitoids than plant odours induced by the saliva of healthy caterpillars. Consequently, plant odours may actually reduce the benefit of attracting parasitoids to a plant.

"Our results demonstrate that the effects of herbivore-induced plant volatiles should be placed in a community-wide perspective that includes species at the fourth trophic level, to improve our understanding of the ecological functions of volatile release by plants," said Dr Poelman. In addition to the ecological aspects of their work, the authors also stress that their findings are important for developing Integrated Pest Management strategies, in which crops are manipulated to control insect pests by using parasitoids.

Although parasitoids are effective biological control agents, this study suggests that using plant odours to optimize biological control of pests may have side effects that could actually reduce the benefit of pest control, said Dr Poelman.


Story Source:

The above story is based on materials provided by Public Library of Science. Note: Materials may be edited for content and length.


Journal Reference:

  1. Erik H. Poelman, Maaike Bruinsma, Feng Zhu, Berhane T. Weldegergis, Aline E. Boursault, Yde Jongema, Joop J. A. van Loon, Louise E. M. Vet, Jeffrey A. Harvey, Marcel Dicke. Hyperparasitoids Use Herbivore-Induced Plant Volatiles to Locate Their Parasitoid Host. PLoS Biology, 2012; 10 (11): e1001435 DOI: 10.1371/journal.pbio.1001435

Cite This Page:

Public Library of Science. "The hungry caterpillar: Beware your enemy's enemy's enemy." ScienceDaily. ScienceDaily, 27 November 2012. <www.sciencedaily.com/releases/2012/11/121127190318.htm>.
Public Library of Science. (2012, November 27). The hungry caterpillar: Beware your enemy's enemy's enemy. ScienceDaily. Retrieved October 24, 2014 from www.sciencedaily.com/releases/2012/11/121127190318.htm
Public Library of Science. "The hungry caterpillar: Beware your enemy's enemy's enemy." ScienceDaily. www.sciencedaily.com/releases/2012/11/121127190318.htm (accessed October 24, 2014).

Share This



More Plants & Animals News

Friday, October 24, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Deep Sea 'mushroom' Could Be Early Branch on Tree of Life

Deep Sea 'mushroom' Could Be Early Branch on Tree of Life

Reuters - Innovations Video Online (Oct. 24, 2014) Miniature deep sea animals discovered off the Australian coast almost three decades ago are puzzling scientists, who say the organisms have proved impossible to categorise. Academics at the Natural History of Denmark have appealed to the world scientific community for help, saying that further information on Dendrogramma enigmatica and Dendrogramma discoides could answer key evolutionary questions. Jim Drury has more. Video provided by Reuters
Powered by NewsLook.com
Black Bear Cub Goes Sunday Shopping

Black Bear Cub Goes Sunday Shopping

Reuters - Light News Video Online (Oct. 23, 2014) Price check on honey? Bear cub startles Oregon drugstore shoppers. Rough Cut (no reporter narration). Video provided by Reuters
Powered by NewsLook.com
Dances With Wolves in China's Wild West

Dances With Wolves in China's Wild West

AFP (Oct. 23, 2014) One man is on a mission to boost the population of wolves in China's violence-wracked far west. The animal - symbol of the Uighur minority there - is under threat with a massive human resettlement program in the region. Duration: 00:41 Video provided by AFP
Powered by NewsLook.com
Breakfast Debate: To Eat Or Not To Eat?

Breakfast Debate: To Eat Or Not To Eat?

Newsy (Oct. 23, 2014) Conflicting studies published in the same week re-ignited the debate over whether we should be eating breakfast. 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