Combined power of the wasp and midge set to oust invasive weed
Press release, November 2010
The dominance of Russian knapweed, which has been crowding out North America’s native plants for the past 100 years, may soon be over as scientists prepare to distribute widely two natural control agents: the gall wasp Aulacidea acroptilonica and the gall midge Jaapiella ivannikovi.
A team from international science organization CABI identified the wasp and midge as natural enemies of Russian knapweed in its original habitats of Central Asia, Iran and Turkey. With the help of partners Biotechnology and Biological Control Agency (BBCA), Italy, Montana State University and the University of Wyoming, USA, Agriculture and Agri-Food Canada (AAFC) and Uzbek Academy of Sciences, Uzbekistan they have conducted detailed research to ensure that these insects will successfully check the spread of Russian knapweed in North America while having no adverse effects on other plants or animals.
Accidentally introduced to North America from Asia in the late nineteenth century, Russian knapweed has since spread across 45 states in the USA and is also considered noxious in several Canadian provinces. Chemical or manual control of the weed is not cost-effective and damaging to the environment, which is why a biological solution was sought.
Plants are usually kept under control naturally by a combination of insects and pathogens (disease-causing organisms) such as fungi. When plants are transported to new areas, very often they will leave their natural enemies behind, which is why so many of them, like Russian knapweed, run wild. Biological or natural control works by going back to the plant’s area of origin to find an insect or pathogen which attacks it there, and then introducing the attacker – or control agent -- to the weed’s new environment.
“The midge established far more quickly than we had expected, and the impact of the midge is almost exactly what was predicted from studies done in the native range,” said Lars Baker, Wyoming Biological Control Steering Committee.
“Russian knapweed is notoriously difficult to suppress and indeed has survived a previous attempt at biological control made in the 1970s. This is why we are subjecting it to a combined assault by two natural control agents, and are continuing to research other agents,” said Urs Schaffner, CABI’s Head of Ecosystems Research. “Meticulous testing in laboratories and in the field suggests that the combination of the wasp and the midge may be highly effective in stopping the spread of this devastating weed. In the future, by integrating other pest management techniques, we aim to bring it under control once and for all.”
The project is funded by the Wyoming Biological Control Steering Committee, United States Department of Agriculture's Animal and Plant Health Inspection Service (USDA-APHIS), Montana Noxious Weed Trust Fund, United States Department of Agriculture – Bureau of Land Management, United States Department of Interior – Bureau of Indian Affairs, and Agriculture and Agri-Food Canada.