Could European fire ants (Myrmica rubra) and Japanese knotweed (Fallopia japonica, Polygonum cuspidatum, Reynoutria japonica, etc. etc.) be in cahoots to take over North America? Researchers from Skidmore College in New York are aiming to find out. After initial investigations revealed that the ants were dining on the nectar proffered along knotweed stems, via structures known as extrafloral nectaries, a biology professor and his students decided to look more closely at the relationship between these two non-native species. Now they're mapping knotweed and ant populations and doing some neat experiments, including wounding knotweed leaves to check whether the ants come to the plant's defense (they did!). News from Skidmore has the whole story.