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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 brown marmorated stink bug

The brown marmorated stink bug is native to parts of East Asia and is invasive in the US, Canada and Switzerland. Here, it is a serious pest of many fruit trees, shrubs and other plants. Chemical control is often used but, with testing, parasitic wasps from China could be used in North America instead. So we want to determine what natural enemies... >>

Controlling wild ginger

Plants from the Hedychium genus are widely loved and cultivated as ornamentals but a few are threatening delicate ecosystems in Hawaii, New Zealand, the Macaronesian Archipelago (Azores, Madeira and the Canaries), Brazil, Australia and La Réunion. We are researching natural ways to manage the plants where they have become invasive, which involves... >>

Biological control of Himalayan balsam

Himalayan balsam has rapidly become one of the UK’s most invasive weed species. A lack of natural enemies allows it to successfully compete with native plants for space, light, nutrients and pollinators, reducing biodiversity and contributing to erosion. Traditional control methods are inadequate. This project involves identifying an insect or... >>

Testing the psyllid: first field studies for biological control of knotweed

Japanese knotweed (Fallopia japonica) is one of the most damaging invasive weeds in the UK. It spreads extremely quickly, preventing native vegetation from growing and is a problem to the construction industry. Current control methods rely mainly on expensive chemicals. But after years of research, we are now releasing and testing a natural... >>

Managing invasive species in selected forest ecosystems of South East Asia

Invasive species are threatening forest habitats in South East Asia. They also indirectly affect the livelihoods of millions of people who depend on forests for food, commodities and energy. CABI and the United Nations Environment Programme (UNEP), in collaboration with partners, have developed a project aimed at conserving globally important... >>

Woody weeds in East Africa

Many exotic trees and shrubs have been introduced into Africa and become destructive invasive species. They're reducing native biodiversity and limiting the livelihoods of those that live in rural communities. CABI is trying to mitigate these impacts in East Africa by generating and sharing knowledge on their effects and finding ways that they can... >>

Controlling pest pear in Laikipia

Pastoralists in northern Kenya are heavily dependent on livestock. Their lives are being devastated by the non-native cactus Opuntia stricta. This weed has invaded the last good grazing land and when livestock and wildlife eat its fruits the spines can cause infection and death. Chemical and mechanical control methods are expensive and... >>