Diversidade de simulídeos (diptera: simuliidae) em riachos da bacia do Rio Comandaí, Alto Rio Uruguai

Abstract

The objective of this work was to study the diversity and spatial distribution of Siminidae (Insecta, Diptera, Simuliidae) in different biotopes of the Comandaí river basin, upper Rio Uruguai, northwest of the State of Rio Grande do Sul. immatures (larvae and pupae) were carried out in nine streams of the Comandaí river basin, being sampled at three points in each of the water courses, thus totaling 27 sampling points. The main substrates investigated for each stream were vegetation and small fragments of rocks. Samples collected in the vegetation were collected manually, and the substrate, together with the larvae and pupae, was transferred directly to a flask containing 96% alcohol. In the collection of fixed individuals to small rock fragments were used plastic boxes containing alcohol, in which the fragments were immersed, and the larvae were released with the aid of a brush. All material collected in the field was taken to the Zoology Laboratory of the Federal University of the Southern Frontier, UFFS, where the screening process was started. The sorting consisted in separating the specimens of Siminidae from the other macroinvertebrates, as well as, removing remains of leaves, branches, roots and impurities that ended up coming with the material collected. Both larvae and pupae were transferred to 70% alcohol flasks. After the triage was completed, using dichotomous keys and illustrated guides, the species identification was performed. The last step consisted of the counting of the biological material. For the Comandai river basin, 10,089 individuals of the same instar (last instar larvae and pupae) were collected from the 27 sample points. The research resulted in the identification of ten species, as follows: Simulium pertinax, Simulium incrustatum, Simulium orbitale, Simulium subpallidum, Simulium jujuyense, Simulium rubrithorax, Simulium subnigrum, Simulium inaequale, Simulium lutzianum and Simulium spinibranchium. The most abundant species was Simulium pertinax, 69.94%. Simulium lutzianum and Simulium spinibranchium were the ones with the lowest occurrence, 0.01%, being considered accidental species. The substrate in which the largest number of individuals was collected was the vegetation, with 74.79%.