Feeding Preferences for Sugars and Amino Acids in the Red Imported Fire Ant, Solenopsis invicta Buren

Ant-hemipteran mutualism is mediated by honeydew through long-term coevolution. To clarify the feeding preferences for the main honeydew components (sugars and amino acids) in the red imported fire ant, Solenopsis invicta Buren (Hymenoptera: Formicidae), this study employed a self-developed feeding preference assay system to systematically determine the feeding and attraction preferences of workers for ten sugars, eleven amino acids, and their different concentrations and combinations in both laboratory and field experiments. Results showed that: (1) S. invicta workers exhibited a significant feeding preference for sucrose and leucine among all tested sugar and amino acid solutions; (2) Feeding preferences for both sucrose and leucine were concentration-dependent. Specifically, preferences for 20% sucrose and 0.5% leucine were significantly higher than for lower concentrations, while not significantly different from higher concentrations; (3) The feeding preference for 10% sucrose or 0.5% leucine alone was higher than that for multi-sugar mixtures or a mixture of all eleven amino acids. However, a mixture of sucrose and leucine solutions significantly enhanced field attraction compared to single solutions of sucrose or leucine. The self-developed feeding preference assay system provides a new tool for measuring feeding preferences in ant colonies under near-natural conditions. Overall, this study systematically clarifies the feeding preference for key nutrients in S. invicta workers and establishes a critical theoretical basis for understanding its foraging ecology and developing highly effective liquid baits.