Efficiency in using genera and families of heteroptera for stream biomonitoring in the Cerrado Biome, Eastern Maranhão, Brazil.

Heteroptera are aquatic insects sensitive to environmental impacts that are frequently used in biomonitoring programs. Resolving families and genera provides consistent responses and can be a useful alternative to accelerate monitoring results and simplify protocols. Our objective was to evaluate which taxonomic levels may be more effective in assessing environmental impacts by testing the following hypotheses: (i) higher taxa of Heteroptera (family and genus) will present congruence with lower taxa (species); (ii) the environmental integrity of the stream will affect the composition of the family, genera and species and will create change points in the abundance and frequency of each taxon. The study was carried out in 30 streams, sampling insects and applying the Habitat Integrity Index (HII). Our main results are presented below: (i) environmental integrity is an important environmental filter in the distribution of the Heteroptera community; (ii) there is ~ 98% congruence between species and genus, ~ 80% between family and genus and ~ 78% between family and species; (iii) there are similarities in the change points between taxonomic levels and (iv) the ecological thresholds detected between families, genus and species. The study shows that the use of genera in Heteroptera is a good alternative in ecological studies when the specific level cannot be used, obtaining information in a similar way to the use of species. HII was efficient in representing aquatic environments and the loss of environmental integrity causes changes in the abundance and frequency of the group at all taxonomic levels. With these results, both hypotheses were corroborated.