Variation in recruitment of red imported fire ants, Solenopsis invicta, to carbohydrate resources in their native and invasive ranges

Mutualisms may encourage the success and spread of invasive species. Invasive ants engage in food-for-protection mutualisms with honeydew-producing hemipterans and plants with extrafloral nectaries. For example, the red imported fire ant, Solenopsis invicta, frequently associates with aphids, scales and mealybugs in the southern US. However, few studies have examined regional and spatial variation in the extent to which S. invicta exploit carbohydrate resources (e.g. honeydew-producing hemipterans and extrafloral nectaries). We compared the propensity of S. invicta to recruit to carbohydrate resources on the ground and in vegetation 1) between native populations (Argentina) and introduced populations (southerneastern US, and 2) among several locations in the US. In Argentina, S. invicta recruited to vials with sugar water on the ground but were not observed climbing vegetation and did not recruit to sugar water vials at 1 or 2 m height. However, in the US, S. invicta were frequently observed climbing vegetation and also recruited to carbohydrate resources above the ground. Solenopsis invicta were frequently collected in vegetation and with honeydew producing hemipterans in the US but not in Argentina. In addition, there was significant variation in the rate at which S. invicta discovered novel carbohydrate resources between sites in the US. These data suggest that opportunities to monopolize arboreal sources of carbohydrates might be much greater in introduced populations. Future studies will test whether or not these proclivities may have aided in the ability of S. invicta and Linepithema humile (the Argentine ant) to invade and spread in the US.