Pesticides may affect the spread of invasive species

Photo Credit: Matthew Townsend Photo Credit: Matthew Townsend

A new study from New Zealand shows that exposure to neonicotinoid pesticides can affect the way that invasive insects interact with native insects. The research focused on the invasive Argentine ant and the native southern ants, examining how their behaviors were altered by exposure to low doses of neonicotinoids. They found that exposure had differing effects on ant behavior, greatly skewing survival in favor of the invasive Argentine ants. While neonicotinoid exposure decreased aggressive behavior in native southern ants, it had the opposite effect on Argentine ants, increasing their aggression to a dangerous level. As a result, Argentine ants were able to completely eradicate native southern ant test populations. Neonicotinoid exposure also decreased Argentine ant brood size, so it is difficult to make conclusions about the future of these invasive populations. However, this study shows a clear example of how neonicotinoids may impact both native and invasive species, with the potential to push native ecosystems out of equilibrium.