First Insights into the Diet of Neotropical Aquatic Insects in Subtropical Temporary Wetlands Through Gut Content Analysis: Implications for Feeding Functional Group Classifications

Abstract Aquatic insects are key components of food webs, performing essential roles in the processing and transfer of energy within temporary wetlands ecosystems. Despite the ecological importance of aquatic insects in these environments, studies evaluating their gut contents remain scarce, limiting our understanding of their trophic role of organisms in these systems. Feeding functional group (FFG) classifications derived from temperate lotic environments may not accurately reflect the trophic dynamics of subtropical ecosystems in the Neotropical region. We investigated the diet of Diptera larvae and Ephemeroptera and Odonata nymphs, identified to the genus level, in subtropical temporary wetlands based on gut content analysis. Taxa were sampled in eight wetlands using a 250-µm mesh net and identified to the genus level. In total, we analyzed 528 guts (Diptera n = 228; Ephemeroptera n = 152; Odonata n = 148), distributed across 12 genera. The most frequent food item was fine particulate organic matter (FPOM), recorded in nearly all individuals. Insects were classified into three FFGs: collectors, scrapers, and predators. The diets of the genera Chironomus , Labrundinia and Miathyria were predominantly composed of FPOM, resulting in differences in their FFG classifications compared with those reported in the literature for temperate regions. Based exclusively on gut content analysis, these genera were classified as scrapers ( Chironomus and Labrundinia ) and collectors ( Miathyria ). We emphasize the need to expand dietary studies to organisms from other orders, especially in subtropical temporary wetlands, which remain understudied, to determine whether the patterns observed here extend to other groups of aquatic insects.