Studies on the Invasion Biology of Social Insects
Abstract
Social insects (e.g., ants, termites) are among the most prolific group of invasive organisms worldwide. The rapid expansion of both their ecological (i.e., habitats) and global (i.e., countries/continents) distributions has likely been facilitated by the world’s most successful invader – humankind. Therefore, for my PhD research, I performed several investigations into the invasions of social insects to gain further insight into how their invasions have been and are currently being shaped in the Anthropocene.
For my first study, I compiled a comprehensive dataset of termite interceptions at US ports of entry spanning the years 1923 to 2017 to elucidate broad patterns in the spread invasive termites to the US. My main findings included a strong regional bias in both the origin (i.e., country/continent) and destination (i.e., port of entry/US region) of interceptions and convincing evidence that invasive termites utilize bridgeheads (i.e., previously invaded locations) to expand their global range. In my next two studies, I reconstructed the invasion histories of two prominent invasive termites – Coptotermes formosanus (native to East Asia) and Reticulitermes flavipes (native to North America). By leveraging existing sample sets previously collected from a large geographic range (i.e., both native and invasive ranges), robust genetic datasets, and approximate Bayesian computation, I inferred a complex invasion history for both species, with multiple invasions from their respective native ranges occurring in conjunction with bridgehead invasions (i.e., invasions originating from a non-native locality). For my final study, I examined Tapinoma sessile’s (odorous house ant) invasion of the urban environment (i.e., cities) from its native natural environments (e.g., forests) across the US. By integrating genetic, chemical, and behavioral data, I discovered strong differentiation between urban and natural populations of the ant in each locality, suggesting cities may be restricting gene flow between habitats and exerting intense selection pressure. Overall, the findings from each of my studies highlight humankind’s powerful and ever-growing influence on the ecological and global distribution of species.
Citation
Blumenfeld, Alexander Joseph (2022). Studies on the Invasion Biology of Social Insects. Doctoral dissertation, Texas A&M University. Available electronically from https : / /hdl .handle .net /1969 .1 /197754.