Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Scientists find insects can alter plant chemistry to help them find mates

19.11.2002


Each spring, amid the decaying rubble of dead prairie plants, emerging male gall wasps find mates by calling upon the chemistry prowess of their predecessors, entomologists scouring Central Illinois have discovered.


Gall wasp larvae feeding inside a stem of Silphium terebinthinacem (prairie dock)
Photos provided by John Tooker.


A female gall wasp Antistrophus rufus
Photos provided by John Tooker.



In the Proceedings of the National Academy of Sciences, they report that as adult gall wasps (Antistrophus rufus) feed in warm weather, they change the ratio of plant chemicals so that males emerging after the winter season can recognize when they are on the right stems at the right time. The study is being published in advance online the week of Nov. 18-22.

The finding is the first to suggest that insects can alter the chemical composition of plants for the purpose of mate location, said Lawrence M. Hanks, a professor at the University of Illinois at Urbana-Champaign.


The study also provides new insight on plant-insect ecology in widely diverse prairie habitats, which in Illinois have dwindled because of agriculture and urban growth to less than 1 percent of the acreage they once covered.

"Prairies hold unique plants and insects that are not thoroughly understood," Hanks said. "This study is important because it shows that insects can influence plants for their own needs, using a substitute for sex pheromones."

Specifically, the researchers found that male gall wasps respond to uneven chemical ratios in the plants. "As the insects feed, they change the plant chemistry, providing cues that help male wasps find females," Hanks said. "This is interesting, because the females are inside the stems, so they are not producing pheromones. It’s a plant’s volatile chemicals that attract males."

In essence, males smell their way to a mate. "They get chemical cues off the surface of the plant," said co-author John F. Tooker, a doctoral student in entomology at Illinois. "It’s called a short-range volatile cue."

"We don’t know how far away they can be and still smell it," Tooker said, "but once they are on the right plant the males antennate the surface and begin looking for mates." This rattling of antennae as they walk along the stem indicates they are on the right plant, "and this behavior helps them to find spots where female wasps will emerge."

"The males find these sites and defend them," he said. The males will head-butt one another, forcing some to leave. Others are driven off by wind or predators, such as spiders and beetles, requiring the wasps to find new stems amid the assorted plant debris.

Males, they found, only choose plant species that are the same as those from which they had emerged. The researchers monitored activity around two commonly found prairie plants: prairie dock (Silphium terebinthinaceum) and compass plant (Silphium laciniatum).

Winged flea-sized adult gall wasps live barely five days in the field, but they emerge continually over a 30-day period. They spend nine to 10 months as larvae living inconspicuously inside of the plants. Adult females emerge from dead stems of the plants, mate and lay eggs in live plant stems, forming galls that protect the larvae and provide nourishment. In the spring, males emerge first from the rotting stems.

Collaborator Wilfried A. Koenig, an organic chemist at the University of Hamburg in Germany, analyzed stem samples collected by Tooker and Hanks. The samples with galls had different enantiomeric ratios of monoterpenes than did the plants without galls.

It is the mix of two chemicals -- alpha and beta pinenes -- that males recognize. "Non-galled plants have a ratio of about 50-50, while galled plants have skewed ratios. If males find a stem with a 50-50 ratio," Tooker said, "they will move on. If they find a stem with a 70-30 or a 100-0 ratio, they likely will stay and find females emerging from it."

Tooker, who is seeking to understand how population control works for the wasps in natural prairie habitats, said the discovery was unexpected. "The botanists know all about the plants we are studying, but we donÕt know much about the insects in prairies," he said. "Gall wasps are very small and easy to overlook. Unless you are in the fields at the right period of the right season you are never going to see them."

Jim Barlow | EurekAlert!
Further information:
http://www.uiuc.edu/

More articles from Life Sciences:

nachricht Microscope measures muscle weakness
16.11.2018 | Friedrich-Alexander-Universität Erlangen-Nürnberg

nachricht Good preparation is half the digestion
16.11.2018 | Max-Planck-Institut für Stoffwechselforschung

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: UNH scientists help provide first-ever views of elusive energy explosion

Researchers at the University of New Hampshire have captured a difficult-to-view singular event involving "magnetic reconnection"--the process by which sparse particles and energy around Earth collide producing a quick but mighty explosion--in the Earth's magnetotail, the magnetic environment that trails behind the planet.

Magnetic reconnection has remained a bit of a mystery to scientists. They know it exists and have documented the effects that the energy explosions can...

Im Focus: A Chip with Blood Vessels

Biochips have been developed at TU Wien (Vienna), on which tissue can be produced and examined. This allows supplying the tissue with different substances in a very controlled way.

Cultivating human cells in the Petri dish is not a big challenge today. Producing artificial tissue, however, permeated by fine blood vessels, is a much more...

Im Focus: A Leap Into Quantum Technology

Faster and secure data communication: This is the goal of a new joint project involving physicists from the University of Würzburg. The German Federal Ministry of Education and Research funds the project with 14.8 million euro.

In our digital world data security and secure communication are becoming more and more important. Quantum communication is a promising approach to achieve...

Im Focus: Research icebreaker Polarstern begins the Antarctic season

What does it look like below the ice shelf of the calved massive iceberg A68?

On Saturday, 10 November 2018, the research icebreaker Polarstern will leave its homeport of Bremerhaven, bound for Cape Town, South Africa.

Im Focus: Penn engineers develop ultrathin, ultralight 'nanocardboard'

When choosing materials to make something, trade-offs need to be made between a host of properties, such as thickness, stiffness and weight. Depending on the application in question, finding just the right balance is the difference between success and failure

Now, a team of Penn Engineers has demonstrated a new material they call "nanocardboard," an ultrathin equivalent of corrugated paper cardboard. A square...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

“3rd Conference on Laser Polishing – LaP 2018” Attracts International Experts and Users

09.11.2018 | Event News

On the brain’s ability to find the right direction

06.11.2018 | Event News

European Space Talks: Weltraumschrott – eine Gefahr für die Gesellschaft?

23.10.2018 | Event News

 
Latest News

Purdue cancer identity technology makes it easier to find a tumor's 'address'

16.11.2018 | Health and Medicine

Good preparation is half the digestion

16.11.2018 | Life Sciences

Microscope measures muscle weakness

16.11.2018 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>