Crayfish, weevils and fungi are being released into the environment in order to tackle invasive species across Britain.

Scientists working for the government have been breeding species in labs to set them loose into the wild to take on Japanese knotweed, signal crayfish and Himalayan balsam, and other species that choke out native plants and wildlife.

They are doing this, in part, to meet 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 establishment of invasive species by 50% by 2030.