Invasive species threaten world’s diversity

Invasive species are costing the world at least $423bn every year and have become a leading threat to the diversity of life on Earth, according to a UN assessment.

• The assessment, produced by the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES), was produced over four and a half years.
• The findings follow a 2019 reportthat warned 1m species were at risk of going extinct, threatened by pollution, climate change, invasive species, the direct exploitation of organisms, and land-use change.
  • Invasive species have contributed to 40% of all known animal extinctions.

Key-highlights of the Report

• Invasive alien species are a major threat to biodiversity and can cause irreversible damage to nature, including local and global species extinctions, and also threaten human wellbeing.
• Top species: The top three invasive species include
  • Water hyacinth, an aquatic plant native to tropical South America that blocks waterways and damages fisheries, the flowering shrub lantana, and the black rat
  • Aedes albopictus(spread West Nile virus)
  • Aedes aegypti (spread Zika virus)
• Dominant areas: Most invasive species reports were noted in the Americas with 34% of all reports, followed by Europe and Central Asia (31%), the Asia Pacific (25%) and Africa (7%).

What is invasive species?

• An invasive species is an organism that is not indigenous, or native, to a particular area.
• Pathways:An invasive species can be introduced to a new area via the ballast water of oceangoing ships, intentional and accidental releases of aquaculture species, aquarium specimens or bait, and other means.
• Not all non-native species are invasive.
  • For example,most of the food crops grown in the United States, including popular varieties of wheat, tomatoes, and rice, are not native to the region.
• Features:To be invasive, a species must 
  • It must adapt to the new area easily.
  • It must reproduce quickly.
  • It must harm property, the economy, or the native plants and animals of the region.

List of invasive flora and fauna in India

Additional examples:

• Cogongrass is an Asian plant that arrived in the United States as seeds in packing material.
• Feral pigs will eat almost anything, including native birds. They compete with native wildlife for food sources such as acorns.
  • Feral pigs spread diseases, such as brucellosis, to people and livestock. E. coli from their feces was implicated in the E. coli contamination of baby spinach in 2006.
• European green crabs found their way into the San Francisco Bay area in 1989. They out-compete native species for food and habitat and eat huge quantities of native shellfish, threatening commercial fisheries.
• Dutch elm disease (caused by the fungus Ophiostoma ulmi) is transmitted to trees by elm bark beetles. Since 1930, the disease has spread from Ohio through most of the country, killing over half of the elm trees in the northern United States.
• Emerald ash borer beetles: Emerald ash borer beetles are invasive insects first discovered in Michigan in 2002 and most likely brought over on packing material from East Asia.