Seasonal Diet Change of the Florida Harvester Ant (Pogonomyrmex badius) and Competition with the Red Imported Fire Ant (Solenopsis invicta)

Pogonomyrmex badius (Florida Harvester Ant) is an ecosystem engineer that feeds on both seeds and insects. Currently, we know little about this species' collection of seeds versus insects or how consumption of these diets might change seasonally. We also know little about how competition with Solenopsis invicta (Red Imported Fire Ant) influences diet choice of Florida Harvester Ants or how it may have contributed towards the observed range decline of the native species. To investigate collection of food items by Florida Harvester Ants and the effects of competition by Red Imported Fire Ants on Florida Harvester Ant foraging, we conducted 2-choice trials of seed and insect baits at 9 different Florida Harvester Ant nests, 5 of which had been treated to eliminate Red Imported Fire Ants. Collections were assessed on 7 separate occasions from July 2020 to April 2021. The collection of seeds and insects by Florida Harvester Ants was largely similar and varied with the seasons. The highest collection rates occurred in the summer and continued into autumn. There was a noticeable decline in collection starting in late November, though this seasonal trend was significant for insect collection but not seeds. The presence of Red Imported Fire Ants decreased the collection of both seeds and insects by the Florida Harvester Ants, though for both types of food items, the difference was significant only at distances closer to their nests.