Feeding habits of Trichoptera (Insecta) larvae of the subtropical Basin

Abstract

The functional feeding groups of aquatic invertebrates indicate both the type of food source used and the feeding mechanism involved. The groups considered were: collectors (gatherers and filterers), shredders, scrapers and predators. Trichoptera larvae display a diversity of trophic adaptations and exploit a variety of microhabitats, but information on their feeding habits in the Neotropical region is still incomplete. The main objective of this paper was to analyze the feeding habits and define the functional feeding groups of Trichoptera recorded in a subtropical Andean basin. The larvae were collected during the low water period and identified to the genus level. Diet profiles were obtained through gut content analysis. Schoener’s Proportional Similarity Index was applied to assess the similarity between diet profiles. A complete linkage dendrogram was obtained and significant clusters (dietary patterns) were identified. The majority of taxa examined prefer more than one food item, being fine particle organic matter present throughout all genera. Metrichia, Hydroptila, Oxyethira and Marilia are categorized as collectors-gatherers. Nectopsyche is defined as collector-gatherer and secondarily shredder. Mortoniella and Helicopsyche are primarily scrapers and secondarily collectors-gatherers. Chimarra shows a collector-filterer habit. Smicridea and Polycentropus are basically predators, but they also feed on particles trapped in nets. Only four of the ten genera analyzed here correspond to the functional groups already reported for other regions.