Crayfish, weevils and fungi released in UK to tackle invasive species such as Japanese knotweed

The South American weevil, Listronotus elongatus, is released to take on the invasive plant floating pennywort. Photograph: Cabi

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.