D3014: Gut content reimagined: Using fatty acid analysis to characterize fire ant diet

Ant colonies range from dozens to several millions of individuals capable of farming, foraging plant matter, scavenging and predating. The adaptability of ants also allows them to become successful invaders. The existence of stable invasive ant populations raises questions about the nature and origin of the resources capable of sustaining them at such high densities. A hypothesis widely accepted today states that high-density ant populations can only be sustained in habitats allowing the production of high amounts of carbohydrates (e.g., plant-produced extrafloral nectar or insect-produced honeydew). However, there has been growing evidence that these highly abundant invasive ants rely on protein consumption, rather than on carbohydrate foraging. It is critical that we understand the diet breadth of invasive ants. Fatty acid analysis (FAA) has been most commonly applied in soil detritivores and microbial communities to characterize detrital food webs, but utilization of this analysis on terrestrial ecosystem is limited. Fatty acid profiles have shown to accumulate and can be traced over at least three trophic levels, which makes it a promising method to analyze the diets of insects with broad diets, like ants. We conducted laboratory experiments to determine whether fatty acid profiles from diet treatments could be detected in the red imported fire ant. We were able to match fatty acid profiles of diet treatments to the fatty acid profiles in ant workers and larvae.