Catálogo polínico de plantas usadas por tres abejorros del género Bombus (Hymenoptera: Apidae) en la Cordillera Oriental de los Andes colombianos

Abstract

More than 20 species of bumblebees are reported in South America, nine of them in the Eastern Cordillera of the Colombian Andes. They are known to be important pollinators, but their distribution has been decreasing due to increasing land use change; this has caused an impoverishment of Andean ecosystems. Identifying and protecting the floral resources used by wild bees is key in the management of wild areas to mitigate the impact of human activities in highly intervened areas such as cities or crops. Pollen analysis is an important tool to preserve floral resources used by bees, but it depends on having pollen catalogs that allow adequate taxonomic identifications. The objective of this study was to develop a pollen catalog of plants used by three of the most common Andean bumblebees, Bombus rubicundus, B. hortulanus and B. pauloensis. Sampling was conducted in six localities of the Bogotá savanna, covering an altitudinal gradient between 2600 and 3500 m a. s. l. Floral samples from all localities were prepared by acetolysis, and then analyzed. A reference catalog was digitized from the pollen extracted from the body of workers of each bumblebee species. Pollen grains were described according to their size and morphology. The similarity of the resources used by the different bumblebee species was compared using Jaccard’s similarity and distance index. Pollen grains from 99 plants were isolated, identified and described, with Taraxacum officinale, Vallea stipularis, Senna multiglandulosa, Trifolium pratense and Trifolium repens being the pollen sources shared by all species. The most generalist species and the one that used the most exotic plants was B. pauloensis. An illustrated pollen catalog is provided with all the resources used by the bees.