Euglossini assemblage (Hymenoptera: Apidae) in Southern Amazonia: mercury contamination and bioindication potential in anthropized environments

Environmental disturbances have become increasingly frequent in the Amazon region. This study evaluated the potential bees of the Euglossini (Hymenoptera, Apidae) as bioindicators of environmental quality across 3 forest types-native, regenerating, and degraded-and assessed mercury (Hg) contamination in the biomass of Eulaema cingulata. Sampling was conducted between March 2021 and May 2023 in the southern portion of the Brazilian Legal Amazon. A total of 362 males euglossine were collected, representing 29 species: 177 individuals in native forest (22 spp.), 104 in degraded forest (20 spp.), and 81 in regenerating forest (23 spp.). Euglossine abundance differed significantly among forest types and varied in the interaction with seasonality. These results indicate that forest conservation status influences the structure of euglossine assemblages. Based on our findings, species such as Eufriesea ornata, Euglossa ignita, Euglossa orellana, Eulaema bombiformis, and Exaerete frontalis are more abundant in conserved forest environments. Although environmental mercury contamination was confirmed in soil and plant samples, Hg was not detected in Eulaema cingulata biomass. Nevertheless, further studies on mercury bioaccumulation in other euglossine species are warranted, given the persistent anthropogenic pressure in the southern Amazon.