Effects of habitat type change on taxonomic and functional composition of orchid bees (Apidae: Euglossini) in the Brazilian Amazon

A study examined the effects of oil palm plantations on orchid bee species using abundance and functional diversity metrics. Male orchid bees were collected in oil palm plantations, legal reserves, and riparian corridors, and characterized using morphological and life-history traits. The study found that males from oil palm plantations were 13.6% bigger than those in legal reserve areas, and bees from riparian corridors showed a similar pattern compared to legal reserve and oil palm areas. The study applied a partial redundancy analysis (pRDA) to test the influence of habitat on taxonomic and functional parameters of orchid bees. The spatial difference explained 6% of the variation in orchid bee traits, but there were no effects of habitat parameters upon functional diversity. Functional diversity was reduced with land use change caused by oil palm plantations. The findings support the belief that many bees are impacted by cultivated lands. However, the functional similarity between legal reserves and riparian corridors reflects common structural elements between them, although no significant relationship was found between functional composition and habitat structure. Bees are one of the main terrestrial insect groups that provide essential pollination services, promoting food security and contributing to the persistence of many native plants and domesticated crops. However, in recent decades, marked changes in most terrestrial ecosystems have contributed to widespread biodiversity loss, changes in the structure of ecological communities, and a decrease of ecosystem services. As a result, the most disturbed sites are characterized by depopulated species pools and homogenous communities, with only a subset of original bee species present dominated by generalist species. Land-use changes and the conversion of natural habitats to other habitat types can impact bee communities by reducing floral and nesting resources. The response of bee species to different forms of habitats is usually determined using metrics related to species richness and/or abundance of bees. In general, species with more specialized niches are more sensitive to the effects of agricultural intensification compared to generalist species. Studies have shown that reduction of vegetation cover influences the distribution pattern of the local bee fauna and exerts a selective pressure upon the communities. Orchid bees (Apidae, Euglossini) are a Neotropical group of bees with a strong relationship with orchid flowers, but most species also pollinate many other plant species. Comprising about 250 species, these bees are sensitive to environmental changes, habitat isolation, and fragmentation. They can also be easily sampled by using inexpensive scent traps, making them an ideal proxy for evaluating effects of habitat disturbances. In recent studies conducted in Eastern Amazon, orchid bees showed the highest species diversity in secondary forests, intermediate levels in primary forests, and only a few species in agricultural areas.