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Improving lives by solving problems in agriculture and the environment

Controlling invasive species

Controlling invasive species

Invasive species, such as weeds, animals and microorganisms are a major issue – threatening ecosystems, habitats and other species when they become established and spread. Many of the species that cause problems are non-native, so we focus on helping to manage these. To understand the impact of invasive species, take a look at our online brochure. 

What are non-native invasive species?

Globalization, climate change and human mobility have fundamentally altered the biological world in which we live. As a result of travel, transport and tourism species have been moved into new environments, where many have established and proliferated.

A species can become invasive when it’s moved from its native ecosystem to a new one. This can be accidental, for example if seeds ‘stow away’ when products are exported from one country to another, but species are also introduced intentionally, because of their perceived benefits. Because they arrive with few or no natural enemies they are often more competitive than the native species, meaning that the non-native species thrive whilst native species suffer.

Why are invasive species a problem?

Invasive species are a global problem. As well as threatening biodiversity, invasive species cause economic losses, and also have an impact on human health and livelihoods.

When a non-native weed species becomes invasive, it can take over grazing land and out-compete crops for limited resources. This can significantly affect yields and production as can insect pests and diseases. Invasive species can also harm the health of people in infected areas: some invasive insects are linked to the spread of diseases, while plants such as ragweed release allergens into the air and are linked to severe hay fever.

What are the options for managing invasive species?

Controlling invasive species can be problematic as chemical and mechanical management options are often ineffective in the long-term, impractical, prohibitively costly, or even illegal.

Biological control is a sustainable alternative way of controlling invasive species. It uses natural enemies of the invasive species, which pose no threat to the new ecosystem and represent a long-term and effective management option.

Prevention is more cost efficient and easier than control. Effective prevention and management requires international cooperation and action. National governments can limit the movement of invasive species across borders through proper quarantine regulation and inspection, and by ensuring food supply chains follow appropriate sanitary and phytosanitary measures.

We’ve been working on invasive species for over 100 years, and we develop workable approaches to tackle the biggest threats.

As well as supporting farmers and smallholders in managing their crop health issues, and promoting efficient farming methods, CABI scientists are world leaders in biocontrol research. We investigate a range of major invasive species problems around the world, the impacts they have and provide solutions. We also advise governments on invasive species policy, and produce books and tools for environmental managers, researchers and farmers on this global issue.

CABI is well positioned to help achieve the Global Goals by 2030 and this means focusing on the impact of invasive species to livelihoods. We have a specific website for this and we want to raise this issue with donors and potential partner organizations around the world. The website includes impact stories, species information and what we're doing.

CABI's invasives blog provides you with stories about our research and debates on topical issues in the field of invasive species from CABI's scientists from around the world.

Biological control of apple leaf-curling midge in Canada

A European biological control agent may help control an exotic pest of apple trees in western Canada. Damage from the apple leaf-curling midge in eastern Canada was effectively reduced by introducing a European natural enemy, Platygaster demades, in the 1990s. The pest arrived in British Columbia more recently, where releases of P. demades are now... >>

Action on Invasives

Invasive species impact the livelihoods of the rural poor who are dependent on natural resources for income and survival. They also undermine international development investment. CABI is developing an ambitious programme to address this complex problem. We aim to target local, national and regional communities and will work across sectors. We... >>

Biological control of hawkweeds

European hawkweeds are invasive in North American pastures, where they escape mowing and even profit from mechanical disturbance. Chemical control with broad-spectrum herbicides is not selective and is relatively expensive, and hawkweeds may recolonize pastures from untreated areas. Insects that feed on hawkweeds in Europe have been studied as... >>

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... >>

Biological control of garlic mustard

Crushed garlic mustard leaves and seeds smell like cultivated garlic and have been used as flavouring in cooking for centuries. Garlic mustard is a brassica from Eurasia that was accidentally taken to North America and became invasive in many of its forests. Together with partners, CABI is exploring the possibility of using specially selected and... >>

Invasive species data

Invasive species are causing species extinction. We are trying to address this problem by providing sound scientific information that will be used by endangered species managers to improve their efforts to recover listed and candidate species affected by invasive species. The information will also be used by invasive species managers to control... >>

Biological control of flowering rush

Attractive pink flowers make the Eurasian plant flowering rush a popular aquatic ornamental. But since it was introduced to North America it has become an aggressive invader of freshwater systems in the midwestern/ western USA and western Canada. One likely reason for this is the absence of the natural enemies that keep it in check in its area of... >>