Soybean aphid as part of a potential four-species invasional meltdown: Evaluation and implications for management

Simberloff and von Holle introduced the term ‘invasional meltdown’ in 1999 to describe interspecific facilitation by invaders that leads to an accelerated rate of invasion or invasion impact. We investigate a potential 4-species invasional meltdown in North America in which invasive earthworms facilitated the spread of common buckthorn, Rhamnus cathartica, which itself facilitated the invasion and rapid spread of the Asian soybean aphid, which uses R. cathartica as an overwintering host. The fourth species is the multi-colored Asian ladybeetle, Harmonia axyridis, an aphid predator that has likely benefited from the presence of soybean aphid in North America. Here, we bring together evidence to support the hypothesis of an invasional meltdown for all of these linkages. We also discuss implications of invasional meltdown for potential management strategies of all of these invasive species.