ABSTRACT. Bee fauna and associated flora from a grassland site in Brazil, surveyed 40 and 20 years ago, were newly surveyed with comparable methodology to evaluate changes in the bee fauna of this site, considering that human population and urbanization has exponentially increased in the last 40 years. In general, bee species richness has declined in 22%, as well as their abundance. Some of the previously abundant species are now absent, including Bombus bellicosus Smith, 1879, Gaesischia fulgurans (Holmberg, 1903) and Thectochlora basiatra (Strand, 1910). No particular trend of differential decrease among either taxonomic or functional groups was observed, except for a minor increase in the proportion of oligolectic species and a 50% reduction in the number of large species. The first two surveys were more similar to each other in species richness per bee genus, while the two most recent grouped together based on measures of anthropogenic impact. Furthermore, the number of plant species visited by bees increased, with a pronounced increase in ruderal and exotic species. Crop cultivation, competition with honeybees and climate changes may all be related to bee decline. Nevertheless, the effects of urbanization, in particular intense land occupation and few preserved natural areas can be pointed as the main causes of species decline. Due to continuing increase in human population, increased erosion in diversity is expected. Habitat protection is an additional challenge to bee conservation in the region, with no local conservation units set aside for grasslands. State and municipal agencies should urgently consider the establishment of reserves for the few remaining patches of natural grasslands.

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Bees ensure 35 % of global food production, but this service is endangered due to several threats. Declines in bumblebee populations (genus Bombus) have been reported worldwide. Bombus bellicosus is one of the rare cases of reported threatened bumblebees in South America. It was once widespread in southern Brazil's grasslands until the 1960s. During that time, that area underwent increasing land use which led to a decrease in bee abundance and richness, and to local disappearance of B. bellicosus. Climate change is also believed to cause declines in the abundance of B. bellicosus. Here we used species distribution models to assess potential effects of climate changes on the distribution of B. bellicosus in southern Brazil, considering both current and future climate scenarios. Our results show that the suitable climatic conditions for B. bellicosus will retreat southwards. A wax cover inside its nests is usually related to Bombus species inhabiting cooler climates. This cover enables the maintenance of higher temperatures inside the nest and may be deleterious for the species under future warmer climates. Continuously growing land use is the second major threat to this pollinator. The results presented here may eventually provide theoretical grounds and enable practical conservation actions for B. bellicosus protection in South America, especially given the potential adverse effects of climate changes for this species.

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Martins A.C., Melo G. A.R. (2016). The New World oil-collecting bees Centris and Epicharis (Hymenoptera, Apidae): molecular phylogeny and biogeographic history. -Zoologica Scripta, 45, 22-33. We present a first comprehensive time-calibrated phylogeny for two Neotropical genera of bees, Centris and Epicharis, whose females collect floral oil together with pollen for larval provisioning, and that traditionally have been grouped in the tribe Centridini. Our analyses rely on a matrix of 167 taxa and 4228 aligned nucleotides for the subfamily Apinae, with denser sample of Centris and Epicharis. Centris and Epicharis are strongly supported monophyletic groups, but Centridini is paraphyletic in relation to the corbiculate bees. The inner phylogenetic relationships of Epicharis agree with the current taxonomic classification. In Centris, three main clades were recovered, namely the Centris, Trachina and Melacentris groups. Inner relationships in Centris suggest the reinstatement of some subgenera and proposition of new ones. Early diversification of Centris and Epicharis took place at the tropical regions of South America. Epicharis and the Melacentris group in Centris mostly diversified in that region, expanding over Central America and tropical North America only recently in the last 3 My. The groups Trachina and Centris present a complex biogeographic history, with expansions to the Nearctic region, the Antilles, and temperate regions of South America in the late Oligocene and Miocene.