| dc.description.abstract | When invasive species arrive to new locations, they do not arrive alone. Invasive species come with a symbiotic entourage and can establish new interactions involving both microscopic and macroscopic organisms in their introduced region. These symbiotic interactions, specifically mutualisms, may ecologically facilitate invasive insect establishment. In addition, population genetic composition of these introduced organisms can influence how they modulate both biotic and abiotic factors. The invasive sugarcane aphid (Melanaphis sacchari Zehntner) that feeds on sugarcane, was recently reclassified by my research group and I as sorghum aphids (Melanaphis sorghi Theobald) when it is found feeding on sorghum plants. This aphid was first reported in the continental United States in 2013. Another invasive insect, tawny crazy ants (Nylanderia fulva Mayr) were first reported in the United States in 1997 in Florida and 2002 in Texas. Since genetics and symbiosis can influence the pestiferous nature of invasive insects, this research focused on three different aspects of insect population genetics and symbiosis. First, the microbial composition of aphids feeding on sugarcane or sorghum was examined across the US. Bacteria that are not normally associated with aphids were identified (e.g., Citrobacter spp.), while facultative symbionts (e.g., Regiella, Hamiltonella, Serratia) commonly found in other aphids were not detected. Next, the interaction between the invasive aphid and ant were examined in greenhouse conditions. Although neither have evolutionary history together, ants tended aphids and aphids presented ants with honeydew. In some instances, this interaction increased biomass when compared with aphids in the absence of ants. Lastly, the fine-scale population genetic structure of tawny crazy ants was assessed using High Throughput Sequencing (HTS) to compare Single Nucleotide Polymorphisms (SNPs) among collections in the US (Texas, Louisiana, Alabama, Mississippi, Georgia, and Florida) and South America (Colombia, Peru, and Argentina). HTS generated thousands of fine-scale molecular markers, allowing for the identification of genetic structure among geographically distinct collections in the US. Integrating both population genetic and microbial analyses can aid in understanding the evolutionary ecology of recently invasive pests. This knowledge can then be used to promote novel approaches toward sustainable pest management. | |
