Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Biocontrol Insect Exacerbates Invasive Weed

04.09.2008
Biocontrol agents, such as insects, are often released outside of their native ranges to control invasive plants.

But scientists in Montana have found that through complex community interactions among deer mice, native plants and seeds, the presence of an introduced fly may exacerbate the effects of the invasive plant it was meant to control. The authors report their results in the September issue of the journal Ecological Applications.

Spotted knapweed, a flowering plant native to Eurasia, was first discovered in the United States in the late 1800s. This broad-leaved plant has an advantage over native plants because its natural enemies, including insects such as European gallflies, do not naturally exist in North America. Thought to have hitched a ride with hauls of alfalfa, knapweed is now widespread in western North America and has become a serious problem in the U.S. across Washington, Idaho, Wyoming and Montana and in Canada across Alberta and British Columbia.

As early as 1971, U.S. scientists began releasing gallflies in an effort to reduce populations of the invasive weed. Like all biocontrol agents, the gallflies were selected because of their specificity to their host plant, leaving little risk of direct harm to other plants.

Adult flies lay their eggs in the weed’s flowers, and after the larvae hatch they induce the plant to grow tissue around the insect, encasing it and isolating it from the rest of the plant.

“The woody galls wall off the fly larvae from within flower head,” says Dean Pearson, lead author on the study and a research ecologist with the U.S.D.A. Forest Service’s Rocky Mountain Research station. “The larvae then overwinter in the seed heads for about nine months. When the plant devotes all that extra energy to producing these galls, it has less energy to produce seeds.”

Scientists and managers expected that this seed deficiency would lead to limited knapweed population growth. An unanticipated side effect, however, involves the flies’ furry neighbors. At the foot of the Sapphire Mountains in western Montana, omnivorous deer mice, whose diet usually consists of native seeds and insects, have also begun to prey on the introduced gallflies.

“These mice are generalists and very effective at exploiting a new resource,” says Pearson. “They can tell which seed heads have the most larvae inside them, and that makes them very efficient.” Pearson says that an average mouse can process 1200 larvae in one night. “A super mouse could go through a whole lot more than that,” he adds.

At Pearson’s grassland study site, spotted knapweed makes up more than half of the plant ground cover. The abundance of knapweed leads to lots of gallfly larvae, which serve as a food subsidy for the mice. Pearson and his coauthor, Ragan Callaway of the University of Montana, found that this extra nourishment bolsters mouse population size, increasing the numbers of hungry mice feeding on their original source of food: the seeds of native plants. As mouse consumption of native plant seeds increases, fewer native plants survive past the seed stage.

Pearson says that this exacerbation of the invasive species’ impact has a lot to do with the effectiveness of the fly at controlling the knapweed.

“If the biocontrol agent is really effective, then it will eventually eat itself out of house and home, and the community interactions become less of an issue,” Pearson says. He points out that even if the fly decimates 80 percent of the knapweed population, the 20 percent of seeds that are left to germinate are often enough to outcompete native plants.

The authors make the case that although biocontrol agents are carefully selected for specificity to their host plants, these restrictions do not prevent them from drastically altering the community food web, which can have far-reaching repercussions. Pearson hopes that a better understanding of food web ecology will lead to more effective tools for invasion control.

“Everything’s interconnected,” says Pearson. “We need to understand the ecology. If we can understand these complexities, we can attempt to minimize the side effects and maximize the effectiveness of our tools.”

To listen to a podcast of Pearson speaking about this paper in ESA’s Field Talk podcast series, please visit http://www.esa.org/podcast. Pearson’s podcast is titled “Biocontrol Insects and the Mammals Who Love Them.”

The Ecological Society of America is the world’s largest professional organization of ecologists, representing 10,000 scientists in the United States and around the globe. Since its founding in 1915, ESA has promoted the responsible application of ecological principles to the solution of environmental problems through ESA reports, journals, research, and expert testimony to Congress. ESA publishes four journals and convenes an annual scientific conference. Visit the ESA website at http://www.esa.org.

Christine Buckley | Newswise Science News
Further information:
http://www.esa.org

Further reports about: ESA Spotted knapweed gallflies insect invasive plants knapweed population

More articles from Ecology, The Environment and Conservation:

nachricht Upcycling of PET Bottles: New Ideas for Resource Cycles in Germany
25.06.2018 | Fraunhofer-Institut für Betriebsfestigkeit und Systemzuverlässigkeit LBF

nachricht Dry landscapes can increase disease transmission
20.06.2018 | Forschungsverbund Berlin e.V.

All articles from Ecology, The Environment and Conservation >>>

The most recent press releases about innovation >>>

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

Im Focus: Superconducting vortices quantize ordinary metal

Russian researchers together with their French colleagues discovered that a genuine feature of superconductors -- quantum Abrikosov vortices of supercurrent -- can also exist in an ordinary nonsuperconducting metal put into contact with a superconductor. The observation of these vortices provides direct evidence of induced quantum coherence. The pioneering experimental observation was supported by a first-ever numerical model that describes the induced vortices in finer detail.

These fundamental results, published in the journal Nature Communications, enable a better understanding and description of the processes occurring at the...

Im Focus: Temperature-controlled fiber-optic light source with liquid core

In a recent publication in the renowned journal Optica, scientists of Leibniz-Institute of Photonic Technology (Leibniz IPHT) in Jena showed that they can accurately control the optical properties of liquid-core fiber lasers and therefore their spectral band width by temperature and pressure tuning.

Already last year, the researchers provided experimental proof of a new dynamic of hybrid solitons– temporally and spectrally stationary light waves resulting...

Im Focus: Overdosing on Calcium

Nano crystals impact stem cell fate during bone formation

Scientists from the University of Freiburg and the University of Basel identified a master regulator for bone regeneration. Prasad Shastri, Professor of...

Im Focus: AchemAsia 2019 will take place in Shanghai

Moving into its fourth decade, AchemAsia is setting out for new horizons: The International Expo and Innovation Forum for Sustainable Chemical Production will take place from 21-23 May 2019 in Shanghai, China. With an updated event profile, the eleventh edition focusses on topics that are especially relevant for the Chinese process industry, putting a strong emphasis on sustainability and innovation.

Founded in 1989 as a spin-off of ACHEMA to cater to the needs of China’s then developing industry, AchemAsia has since grown into a platform where the latest...

Im Focus: First real-time test of Li-Fi utilization for the industrial Internet of Things

The BMBF-funded OWICELLS project was successfully completed with a final presentation at the BMW plant in Munich. The presentation demonstrated a Li-Fi communication with a mobile robot, while the robot carried out usual production processes (welding, moving and testing parts) in a 5x5m² production cell. The robust, optical wireless transmission is based on spatial diversity; in other words, data is sent and received simultaneously by several LEDs and several photodiodes. The system can transmit data at more than 100 Mbit/s and five milliseconds latency.

Modern production technologies in the automobile industry must become more flexible in order to fulfil individual customer requirements.

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Munich conference on asteroid detection, tracking and defense

13.06.2018 | Event News

2nd International Baltic Earth Conference in Denmark: “The Baltic Sea region in Transition”

08.06.2018 | Event News

ISEKI_Food 2018: Conference with Holistic View of Food Production

05.06.2018 | Event News

 
Latest News

Rapid water formation in diffuse interstellar clouds

25.06.2018 | Physics and Astronomy

Using tree-fall patterns to calculate tornado wind speed

25.06.2018 | Earth Sciences

'Stealth' material hides hot objects from infrared eyes

25.06.2018 | Power and Electrical Engineering

VideoLinks
Science & Research
Overview of more VideoLinks >>>