The grey squirrel, the fire ant, the blue crab... An unprecedented journey around the world among invasive alien species to learn about their dangers and how to prevent them.

An invasive species is an organism that is not native to a particular area, that readily adapts to the new environment, reproduces rapidly, and causes damage to property, the economy, or indigenous plants and animals. Since the dawn of time, humans have carried plants and animals with them on their travels, introducing them into environments different from their native ones. The transport of species has contributed to the history of civilisations and enriched our lives, for example by spreading foods such as tomatoes, potatoes and prickly pears from the Americas to Europe. But unfortunately, it is not always a happy story: outside their natural habitat, these species can trigger ‘biological invasions’, with disastrous consequences for us as humans and for the ecosystems involved. With globalisation, these invasions have accelerated at an unprecedented rate, making them one of the most serious threats to biodiversity. So what are the most urgent measures to prevent biological invasions? And what can each of us do to reduce these risks? Piero Genovesi also takes a closer look at the tools being used in different countries and explains how we can intervene to reverse the trend if we really want to protect nature and ourselves.