2nd Place: D3151: Understanding connections between diets of honeydew insects and fire ants in longleaf pine savannas of North Carolina

Fire ant (Solenopsis invicta) diets consist of different foods, including sugary plant juices obtained from honeydew insects, facilitating rapid colony growth and possibly invasion of new sites. Longleaf pine savannas are areas of conservation concern in the coastal region of North Carolina and home to unique and protected flora and fauna. Our previous work at these sites in 2017 indicated fire ant invasion. Our Sanger data (ITS2) indicated ryegrass (Lolium spp.) was a significant component of fire ant diets, despite ryegrass not appearing in these sites. We hypothesized that mutualistic relationships between fire ants and honeydew insects are allowing fire ants to access ryegrass and to exploit the savanna ecosystems. We used ITS2 and rbcLa DNA barcodes to compare plant diets of fire ants collected in 2017 with plant diets of honeydew insects collected in 2021. The ITS2 barcode showed ryegrass in the diets of both honeydew insects and fire ants, while the rbcLa barcode showed no ryegrass in the diets of either. Some dietary overlap occurred in other plant foods. In the future, we plan to use Sanger and next-generation sequencing to compare the diets of honeydew insects and fire ants collected during the summer of 2022 to determine if there is a strong connection between their diets. Our data have important implications for the role of invasive species in protected areas.  We will share our findings with The Nature Conservancy and other organizations to aid in the conservation of these pine savanna ecosystems.