Orchid bees in riparian and terra-firme forest fragments in an urban matrix in southwestern Brazilian Amazonia

ABSTRACT Riparian forests are important ecosystems that support an enormous biodiversity in Brazil. Despite being protected under Brazilian legislation, these forests suffer great impact from the fragmentation of habitats. Orchid bees are a key group of pollinators in the Neotropical region, yet few data are available on the assamblage structure of these bees in riparian forests. We evaluated the role of fragments of riparian and terra-firme forest on the conservation and maintenance of orchid bees in an urban landscape in the southwestern Amazon basin. Specifically, we evaluated whether bee assemblages in riparian and terra-firme forests differed significantly in abundance, species richness and composition. We also evaluated whether species richness and abundance of bees vary with the size of the forest fragment. Male bees were attracted using odoriferous baits and collected with entomological nets in 10 forest fragments. There was no significant difference between riparian and terra-firme fragments in species abundance, richness and composition, but there was a positive correlation between fragment size and species richness and abundance. Our results suggest that, in an urban landscape, the remaining riparian and terra-firme forest fragments still could maintain 62.7% of the orchid bee species known to occur in the region, reinforcing the conservation value of these forest remnants. Our findings indicate that these fragments provide a potentially important habitat for the maintenance of local bee populations in the landscape.

First Case of Gynandromorphism in the Orchid-Bee Eulaema meriana (Olivier) (Hymenoptera: Apidae)

The discovery of the first case of gynandromorphism in Eulaema meriana (Olivier) is described and illustrated. A specimen from Los Ríos, western Ecuador, discovered in the Instituto Nacional de Biodiversidad (MECN) collection, exhibits mostly male features on the left and female features on the right, except for the jugal comb of the hind wing and terminalia. This finding is compared to other reported cases in orchid bees.

In euglossine we trust as ecological indicators: a reply to Añino et al. (2019)

Orchid bees have been considered as good ecological indicators of habitat disturbances but recently Añino et al. (2019. Sociobiology, 66: 194-197) highlighted reasons why Euglossini role as indicators should be reevaluated. Despite agreeing with some points raised by them, we present an alternative view for the use of orchid bees as indicators. For us, the main problematic issues are: (i) the authors do not present a clear definition of ecological indicator, including its role as an indirect measure of biota response to disturbed environments; (ii) they do not properly acknowledge the relative good taxonomic status of orchid bees when compared with the remaining bees; (iii) and they do not distinguish the use of particular Euglossini species as indicators in certain circumstances. In spite of some knowledge gaps, we argue that Euglossini is a good candidate to be ecological indicators in tropical forests, maybe the best candidate among all the bees.

Wind drives temporal variation in pollinator visitation in a fragmented tropical forest

Wind is a critical factor in the ecology of pollinating insects such as bees. However, the role of wind in determining patterns of bee abundance and floral visitation rates across space and time is not well understood. Orchid bees are an important and diverse group of neotropical pollinators that harvest pollen, nectar and resin from plants. In addition, male orchid bees collect volatile scents that they store in special chambers in their hind legs, and for which the wind-based dispersal of odours may play a particularly crucial role. Here, we take advantage of this specialized scent foraging behaviour to study the effects of wind on orchid bee visitation at scent sources in a fragmented tropical forest ecosystem. Consistent with previous work, forest cover increased orchid bee visitation. In addition, we find that temporal changes in wind speed and turbulence increase visitation to scent stations within sites. These results suggest that the increased dispersal of attractive scents provided by wind and turbulence outweighs any biomechanical or energetic costs that might deter bees from foraging in these conditions. Overall, our results highlight the significance of wind in the ecology of these important pollinators in neotropical forests.