Invasive plants can pose serious threats to native species, ecosystems, human health and many sectors of the economy such as agriculture, forestry and tourism.
When plant species grow outside of their natural distribution range they are called non-native or exotic. One reason why these non-native plants can become invasive is the lack of natural enemies that limit their vigour, density and spread.
Classical biological control, or biocontrol, is the use of living organisms such as insects, mites or fungal pathogens to control pest populations. It levels the playing-field by reintroducing some of the specialist natural enemies that help control the invasive species in its native range. The aim is not to eradicate the invasive plant, but to bring its density below an appropriate ecological or economic threshold.
Biocontrol is an environmentally friendly, cost-effective and sustainable way of managing invasive species and has been used effectively for more than 100 years.
What we offer
CABI has over 60 years’ experience of working on the biological control of invasive weeds and is one of the few organisations in the world that can simultaneously research and develop insect, mite and fungal control agents.
Any organism intended for the control of a non-native invasive plant undergoes an extensive series of tests to determine its environmental safety before considering its release. More than 50 biological control agents have been released based on the work carried out at CABI in Switzerland alone. Many of these are currently contributing to the successful control of important North American weeds such as leafy spurge, toadflaxes, knapweeds, houndstongue and purple loosestrife.
Our team of highly experienced staff works with customers to develop scientifically sound biological control solutions based on thorough research. We advance the science of biological weed control by carrying out in-depth studies, often in collaboration with universities or other research organizations.
Our work is generally carried out in a number of phases which typically include the following tasks:
See an example of our work:
Detailed annual reports for each project can be requested from the respective project manager. See our 2022 weeds progress report.
The team and key contact
The team working at CABI in Switzerland is led by Dr Philip Weyl and includes research scientists, MSc and PhD students, garden technicians and temporary research assistants.
The co-supervision of MSc and PhD students by CABI staff is an important component of CABI’s work and adds both breadth and depth to the quality of our scientific research.
We are currently investigating potential biocontrol agents for around 20 invasive plants mainly for the US and Canada, but also for Australia and South Africa. After a long period of no releases in North America, a total of seven agents have been released based on work at CABI in Switzerland in the last five years and more are in the pipeline.
Project highlights include:
- In 2022, the Canadian Food Inspection Agency (CFIA) approved release of the weevil Bagous nodulosus against flowering rush, the gall-forming mite Aceria angustifoliae against Russian olive and the rhizome-mining moth Dichrorampha aeratana against oxeye daisy. Releases are planned for all three species in 2023
- USDA APHIS Technical Advisory Group (TAG) recently recommended release of the same agents above as well as the seed-feeding weevil Mogulones borraginis against houndstongue
- Since approval by the Canadian Food Inspection Agency (CFIA) in 2018 of two moths, Archanara neurica and Lenisa geminipuncta against common reed, over 17,000 insects have been released at 13 sites across southern Ontario
- In a global first for biocontrol in the mustard family, the root-crown mining weevil, Ceutorhynchus scrobicollis, was released on garlic mustard field sites close to Ottawa, Canada in August 2018, with initial signs of possible establishment in 2022
- See a recent update on the biological control success of Russian Knapweed from the Colorado Department of Agriculture.
Biological control of lesser calamint
Lesser calamint is an aromatic perennial herb that has been introduced to New Zealand from Europe. Currently present on the east coast of the North Island, lesser calamint is considered an emerging weed; it is affecting desirable pasture species and having negative economic impacts. CABI is conducting field surveys and searching for natural enemies from lesser calamints area of origin in Europe that could be introduced in New Zealand as biological control agents.
Biological control of hawkweeds
European hawkweeds are invasive in North American pastures, where mechanical methods of control are difficult and ineffective. Chemical control with broad-spectrum herbicides is not selective and relatively expensive, with the weed often recolonising untreated pastures. Insects that feed on hawkweeds in Europe have been studied as potential biological control agents for North America since 2000. Two agents have been released in Canada – the gall wasp Aulacidea subterminalis in 2011 and the hoverfly Cheilosia urbana in 2017.
Revisiting biological control of field bindweed
Field bindweed is a Eurasian vine whose dense creeping and twining growth smothers other vegetation and its long-lived seeds and deep roots make it hard to control. It is a noxious weed of agricultural fields in temperate regions and has become invasive in North America. CABI is studying sustainable control methods using host-specific natural enemies, which could be introduced into North America as biological control agents.