Carbohydrate resources drive increased ant recruitment in a saline coastal ecosystem

Maintaining a physiological stoichiometric balance is a fundamental driver of foraging behaviour; yet, resource availability varies across trophic levels and vegetation strata. Therefore, primary consumers and predators may experience distinct nutritional opportunities between epigaeic and arboreal habitats. We investigated how ant communities respond to carbohydrates availability in the Brazilian Restinga - a coastal ecosystem characterized by sodium saturation and low carbohydrate availability. For that, we experimentally supplied carbohydrates (C₁₂H₂₂O₁₁, 20%), salt (NaCl, 1%) and water in both epigeic and arboreal strata to assess recruitment responses across the overall ant community as well as predominantly primary consumers and predominantly predatory ants separately. Carbohydrates were more attractive to the overall ant community, attracting eight times more species and 15 times more ant individuals than salt. This higher recruitment was consistent across feeding guilds, with primary consumers and predators exhibiting 17-fold and 42-fold increases in individual recruitment to carbohydrates as many as salt baits. Although primary consumers were recruited more in the arboreal stratum and predators in the epigeic stratum, recruitment to carbohydrate baits was consistent across vegetation strata for both the overall ant community and the feeding guilds. In conclusion, our findings show that carbohydrates in a saline coastal ecosystem strongly act as an important resource influencing ants' foraging behaviour across vegetation strata. These results highlight how stoichiometric imbalances dictate foraging decisions and community dynamics and provide insights into how resource availability influences ant-mediated ecological functions in saline environments.