99 of the worst

The IUCN's list of ‘100 of the World's Worst Invasive Alien Species' has been reduced to 99, following the eradication of the Rinderpest Virus from the wild. We believe that we should now select a new candidate to fill in the 100th place on this list, thereby raising awareness of this important issue.

We wish to invite you to participate and have your input in this selection.

10 candidates

We have compiled invasive alien species inventories/checklists from 16 global and national databases. We obtained over 10,000 invasive alien species that we ranked based on the number of times they were listed. We then accounted for emerging threats, i.e. species that are not yet widespread but that are known to have major impacts and/or a high spreading rate, so that they would go up in the ranking.

We selected the first 50 species and assigned to each of them a score of (i) spread - the number of continents already invaded, and (ii) impact: either ecological, economic and/or health. We finally eliminated those species which genus was already represented in the 100-list as well as those that had a strong positive value (cultural, economic). We then selected the 10 species with the highest sum of scores.

The 100th

We now propose this list of ten invasive alien species to the community of invasion biologists for them to vote and collectively select the species that would best serve the community as the latest and 100th representative for the ‘100th of the World's Worst Invasive Alien Species’ list. Following the same thinking behind the development of that list, this approach is not meant to be a precise selection of "the" worst but rather a rational selection of "some of the" worst, as it is difficult to objectively classify one species to be ‘worse' than another.

To participate, simply leave a score on the following webpage. Voting is open till the 28th of February 2013. Once the vote is closed, we will notify you by email about the species that the community has chosen to add to the IUCN list.