Diet analysis of Cricotopus sp. larvae (Diptera: Chironomidae), fourth stage, in different artificial substrates and hydrological phases, in the upper Paraná river - DOI: 10.4025/actascibiolsci.v31i4.3522

Abstract

In Brazil, studies on the diet of Chironomidae larvae are still scarce and these data are important to understand the trophic structure and organization of aquatic ecosystems. In this study, we identified the main food items consumed by Cricotopus sp. and compared possible differences in the larval diet at different artificial substrates and hydrological phases. We used four types of artificial substrates: X-shaped wood (MADX); X-shaped nitacetal plates (NITX); tube-shaped PVC (PVCT) and tube-shaped galvanized metal (METT), each with three replicates. Samplings were undertaken fortnightly, between August 2004 and December 2005. Cricotopus sp. diet was composed by detritus, algae and fungal hyphae. Detritus was the main food item, with values above 50% of total intake. The results indicated that Cricotopus sp. is a collector species and, regardless of substrate, these larvae feed on available resources in the environment. However, the changes in hydrological regime of the Paraná river can influence the food resource availability, mainly some Diatoma genera such as Melosira sp., which were consumed in high quantity only during the low water phase