Abstract

DUARTE RAMOS, Edison Jahir  and  REINOSO-FLOREZ, Gladys. Composition and structure of larval Trichoptera (Arthropoda: Insecta) assemblages of the Las Perlas stream, Ibagué, Colombia. Rev. acad. colomb. cienc. exact. fis. nat. [online]. 2020, vol.44, n.171, pp.471-481.  Epub June 11, 2021. ISSN 0370-3908.  https://doi.org/10.18257/raccefyn.964.

The Trichoptera order is a very abundant and diverse group of insects in aquatic ecosystems where it functions as the base of the trophic chain, degrades organic matter, and is a sensor of physicochemical alterations. In this study, we aimed at determining the composition and structure of the Trichoptera on the substrates, as well as the physical, chemical, and microbiological variables of the Las Perlas stream. Three stations of the stream were monitored during six sampling periods; the collection was carried out with Surber samplers on four substrates (sand, gravel, leaf litter, and rock). We collected 5,831 organisms distributed in 17 genera and nine families, where the genus Helicopsyche (Helicopsychidae) was the most abundant (2,200 ind.) followed by Smicridea (1808 ind.). The NMDS ranking analysis supported on ANOSIM showed that there were significant differences between the assemblies of the three stations evaluated. Rock and gravel substrates are preferred by most Trichoptera to establish their filtration nets and pupal cases. Temporally distribution of the organisms is modulated by the effect of the flow with the periods of low rainfall M3 and M4 as those of a higher density of organisms. Finally, the analysis of canonical correspondence showed that no variable had conditioning effects on the distribution of organisms. These results broaden the knowledge of the Trichoptera of the region and provide information on the environmental status of the Las Perlas stream, an important source and supplier for the population of Ibagué.

Keywords : Freshwater ecosystems; aquatic insects; rivers.

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