Successful invasions of hymenopteran insects into NW Patagonia

Abstract

We describe the successful invasion of hymenopteran insects into NW Patagonia. We analyse the importance of the invading species and the characteristics of the invaded community, as well as the role of disturbance on the invasion process, by presenting the most conspicuous of the best documented case studies: the wasps Vespula germanica and Sirex noctilio, the bumblebee Bombus ruderatus, and the leaf cutting ant Acromyrmex lobicornis. In their native habitats, these insects are common and have a wide geographical range. In turn, ecological plasticity appears to be the most important demographic trait related to invasion success shared by these species. We believe that climatic matching between the community invaded and the invader's native range together with the absence of natural enemies are the community characteristics better related to invasion success. The role played by biotic resistance remains unclear. The successful establishment of the studied cases is related to some extent to resource liberation due to exogenous disturbance, or competitive displacement of a native species. This might suggest that the native hymenoptera community of NW Patagonia is species saturated, which in turn, could imply that species interactions are important in the community structure in environments where physical variables have been regarded as key factors.