Crayfish, weevils and fungi are being released into the environment to combat invasive species across Britain.
Scientists working for the government are breeding species in laboratories to release them into the wild to control Japanese knotweed, signal crayfish and Himalayan balsam, among other species that suppress native plants and wildlife.
They are doing this in part to meet the tough targets set by the Department for Environment, Food and Rural Affairs in its recently announced environmental improvement plan. Ministers have directed the Animal and Plant Health Agency (Apha) to reduce the spread of invasive species by 50% by 2030.
Olaf Boy, deputy chief scientist for non-native species at Apha, said: “The science of biological control is constantly evolving. It does work for those species that have been introduced quite a long time ago, but we have not been able to prevent their arrival or detect them early and respond quickly.”
Scientists are identifying which species can control invasive pests, killing them and reducing their ability to spread without harming other organisms. Bui said the benefit of biological control agents is that they reduce the need for human labor.
This includes controlling the floating jellyfish, which is spreading and suffocating life in rivers, by releasing the South American weevil. Lystronotus elongata. Where weevils have overwintered for several years, the biomass of floating St. John's wort decreases in a number of release sites.
Defra has also recruited specialist scientists to the Center Agriculture and Bioscience International (Cabi) to conduct research on the biological control (biocontrol) of using natural living organisms to control Japanese knotweed. Kabi targeted the species by releasing a leaflid. Afalara itadoriwhich feeds on the plant.
Similarly, Kabi tests the release of rust fungus. Puccinia komarovii var. glandular deal with Himalayan balsam. Defra said the results of the release were encouraging and would continue on compatible sites.
“Once the biocontrol agent is working properly, it should begin to naturally spread throughout the habitat where the non-native species live and begin to reduce the population of the non-native species,” Bui said. “The hope is that once it starts to become established in the wild, it will sort of start to take over and human efforts will start to decline significantly.”
In addition to releasing biological control agents into the wild, government scientists are breeding endangered species to protect their populations from invasion. The native British white-clawed crayfish has disappeared from much of the country since the introduction of the invasive American signal crayfish in the 1970s. These non-native creatures outcompete native crayfish and carry a deadly plague, making eradication or containment nearly impossible.
Invasive species experts have created protected “ark sites”: safe habitats where white crayfish can survive unthreatened. A new hatchery has been opened in Yorkshire to release crayfish into the wild in safe locations, while in Devon the Wildwood Trust is expanding its hatchery, building a special ark pond and rescuing crayfish from endangered rivers. So far, more than 1,500 crayfish of reproductive age have been transferred to eight safe locations in Gloucestershire.
The creatures Bui is most concerned about appearing in the wild including raccoons and raccoon dogswhich are kept as pets but are very good at escaping into the wild.
Medium-sized predators can harm the amphibians and small birds they feed on, he said. Currently, owners of raccoons and raccoon dogs do not require state registration, although their breeding and sale are prohibited.
Social media trends portraying raccoons as cuddly and desirable pets can be worrying, he said: “You do see things like raccoons and raccoon dogs etc popping up on social media. Especially raccoons, they're quite cute and cuddly, and you can imagine a TikTok trend might encourage people to consider getting one. Apparently, years ago we had an interest in the turtles from Teenage Mutant Ninja Turtles.
He added: “If you have a raccoon, you really need to know how to store it securely so it doesn't escape. You don't really want predators of that size to establish themselves and spread across the country because that would have a knock-on effect on biodiversity. But they're also potential disease vectors.”
Biosecurity Minister and Labor peer Sue Hayman said: “As climate change arises, we are constantly assessing new risks and threats, including from invasive plants and animals, and managing the impacts of species already native to this country. Invasive non-native species cost the UK economy almost £2 billion a year and our Environment Improvement Plan includes plans to reduce their numbers to protect native wildlife and farmers' livelihoods.”
