Invasive Species

It's official: the UK has a slug problem. This week, researchers from the John Innes Centre in Norwich asked the public for help to help them track down the Spanish slug, a rapidly reproducing invasive species that eats crops and is not deterred by slug pellets. Here's your quick fire science on invasive species, with Matt Burnett and Simon Bishop.

- An invasive species is any animal or plant that has come from another area, which disrupts the environment and outcompetes native species.

- Humans like to travel the world, and sometimes other species like to come with us. Mosquitoes spread to some Pacific islands by hitching a ride in the wooden planks of boats. Unfortunately, they also took Dengue fever with them.

- Dutch Elm disease has also been ravaging woodlands in Europe and North America after accidental introduction from Asia. Our trees just weren't prepared for it, having never needed to evolve resistance.

- Zebra mussels from Russia spread around the world in ships. It costs the UK water treatment industry millions of pounds every year to clear them out from pipes.

- Species have also been introduced to countries just because they are exotic. Japanese knotweed was brought to Britain in the 19th century because people thought it looked pretty, but gardeners soon found that it can grow through concrete, damaging everything from roads to drainage systems.

- The American crayfish was brought to Britain to give farmers extra income, but it escaped the farms and outcompeted native species in the wild. But good news! Campaigners are encouraging fishing of the aggressive beasts, which go very well in a salad.

- Farming can also make life easy for invaders. In Central America, intensive farming of coffee uses pesticides, which have disrupted the food chain and allowed the spread of rust fungus. A poor coffee harvest this year led Guatemala to declare a state of emergency.

- In 1935, the poisonous cane toad was imported to Australia to eat crop pests, but now it is the pest. There are hundreds of millions of them, roaming the outback with no predators.

- Nowadays, the International Organisation for Biological Control are the people looking for safe species to use in pest control.  At the moment, they are looking for a natural enemy of the cabbage moth, but one that won't go on to become a problem itself.

- To prevent the spread of pests, countries have strict customs rules. All planes arriving in Australia, for example, are sprayed with insecticide.

- You can help researchers map the infestation of Spanish slugs by sending your sightings to slugwatch.co.uk.