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 2024 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.
Philip Weyl
Head Weed Biological Control
T: +41 (0)32 421 48 76 E: p.weyl@cabi.org
Project highlights
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 2024, work on three new biological control targets gained traction for the CABI in Switzerland team. These include blueweed, Echium vulgare, European frogbit, Hydrocharis morsus-ranae, and water soldier, Stratiotes aloides.
- In 2024, the weevil, Bagous nodulosus, against flowering rush was released in Canada and the permit for release in the USA was granted. Plans for mass-rearing are underway and additional releases in Canada and the USA are planned in 2025.
- Both the gall-forming mite, Aceria angustifoliae, against Russian olive and the rhizome-mining moth, Dichrorampha aeratana, against oxeye daisy were released in Canada with early signs of establishment.
- The petition was submitted in 2024 for the seed-feeding weevil, Ceutorhynchus constrictus, to the USDA-APHIS Technical Advisory Group (TAG) as well as the Biological Control Review Committee (BCRC) in Canada.
- Since the release of two moths, Archanara neurica and Lenisa geminipuncta, against common reed, there are promising signs of establishment and spread as the monitoring of these insects continues.
Related Projects
Controlling hoary cress in North America
Trade in seed brought crops to new regions, but many weeds were spread by this route too. Whitetops, also known as hoary cresses, arrived in the USA as contaminants of seed from Eurasia. They are now aggressive invaders of crops, rangeland and riverbanks. One reason for this is the absence of the natural enemies that keep them in check in their area of origin. CABI staff in Switzerland are looking into the prospects for biological control of these invasive plants.
Giving dyer’s woad the blues
Dyer’s woad is an ancient source of blue dye and was grown as a textile dye crop in Europe and Asia for centuries. It was introduced to North America by early colonists, but escaped cultivation. Today, it is recognized as a serious weed in the western USA. One reason for its impact is the absence of the natural enemies that keep it in check in its area of origin. CABI is searching for specialist natural enemies in Europe that could potentially be introduced for its biological control.
Exploring options to control Canada thistle
Despite the name, Canada thistle’s natural home is Eurasia. It has spread throughout the temperate world to become one of the worst weeds in rangeland and crops. One reason for this is the absence of the natural enemies that attack it in its area of origin. In North America six insect natural enemies have been introduced as biological control agents to try to control the weed but they have had little impact. CABI has been investigating whether disease-causing fungi might be the answer.
