Invasive species a growing and costly threat, key report to find

Invasive species that destroy forests, ravage crops and cause extinctions are a major and growing threat worldwide, a landmark UN-backed assessment is poised to report. The science advisory panel for the UN Convention on Biodiversity, known by its acronym IPBES, will release on Monday the most comprehensive assessment of so-called "alien species" ever assembled. Some invasive species are accidental arrivals, hitching rides in the ballast water of cargo ships, the containers in their holds, or in a tourist's suitcase. Invasive species are a significant cause of extinctions, along with habitat loss, global warming, pollution and direct exploitation for food or body parts. A global treaty to protect biodiversity hammered out in the Canadian city of Montreal last December sets a target of reducing the rate at which invasive alien species spread by 50 percent compared to current levels.