Does Barypenthus concolor Burmeister (Trichoptera: Odontoceridae) select particles of different sizes for case building?

Abstract

Many species of Trichoptera larvae use organic or inorganic particles to build cases that protect them from predators. The study of the wide variety of structures produced by trichopterans is important to understand the evolution of case building behavior. The objective of this work was to investigate if larvae of Barypenthus concolor (Burmeister) are capable of selecting particles of specific sizes to build their cases. The study site was an altitudinal stream in Serra do Cipó National Park, MG, Brazil). Cases and substrate samples were collected at three sites of the stream and submitted to granulometric analyses. The average mass of each particle size found in each site was used to determine the particle size proportion present in the substrate. The proportions of particle size of each case (site I: n = 10, site II: n = 19, site III: n = 13) were also analyzed. Possible differences between the proportions of the particle sizes of the substrate and of those used by B. concolor larvae were assessed by the Chi-square test. Medium and fine gravel predominated at the three sites (>70%). There were no significant differences between the expected and observed particle size proportion in the cases. Therefore, B. concolor does not select specific particle sizes for case building.