Abejas Euglossinas (Apidae: Euglossini): un enfoque de conservación e importancia ecológica / Euglossine bees (Apidae: Euglossini): a conservation approach and ecological importance

Introducción. Las abejas euglossinas son consideradas indicadoras de calidad de hábitat debido a su sensibilidad a los cambios ambientales, este grupo es fundamental para mantener la estabilidad de los ecosistemas debido a su función polinizadora. Sin embargo, los procesos de deforestación están afectando negativamente a sus poblaciones. Objetivo. Conocer la importancia ecológica y la diversidad de este grupo taxonómico en Colombia, además de presentar información sobre su biología y procesos de conservación Método. Se realizó una búsqueda sistemática de información científica en bases de datos digitales, con documentos publicados en revistas científicas nacionales e internacionales. Se tuvieron en cuenta los artículos con información biológica y de conservación de las euglossinas y se descartaron los artículos con enfoque genético, generalidades de Hymenoptera y Apidae y artículos taxonómicos. Resultados. Según los artículos consultados, el descubrimiento de la relación planta-animal de las abejas con las orquídeas y de la preferencia de los machos por los aromas naturales de las flores, han facilitado realizar varias investigaciones con aportes significativos en biología, ecología y taxonomía de este grupo. Se evidencio que Colombia presenta más riqueza de especies que los países líderes en investigación de euglossinos. Según los artículos revisados, las abejas euglossinas prefieren zonas con vegetación densa y bosques conservados y evitan zonas desprovistas de vegetación. Discusión. Las abejas euglossinas son importantes para la manutención de los ecosistemas debido a su función polinizadora que permite la estabilidad y subsistencia de muchas especies vegetales. La deforestación afecta negativamente las poblaciones de abejas euglossinas y las restringe a parches de bosques, lo que reduce su capacidad polinizadora y pone en riesgo la estabilidad de muchas especies vegetales. Conclusión. Esta revisión brinda una perspectiva actual sobre la diversidad de este grupo taxonómico a nivel nacional, además nos permite conocer la importancia que tienen para el equilibrio de los ecosistemas.

Unraveling the Olfactory Biases of Male Euglossine Bees: Species-Specific Antennal Responses and Their Evolutionary Significance for Perfume Flowers

Male euglossine bees exhibit unique adaptations for the acquisition and accumulation of chemical compounds from “perfume flowers” and other sources. During courtship display, male bees expose perfume mixtures, presumably to convey species-specific recognition and/or mate choice signals to females. Because olfaction regulates both signal production (in males) and signal detection (in females) in this communication system, strong selective pressures are expected to act on the olfactory system, which could lead to sensory specialization in favor of an increased sensitivity to specific chemical compounds. The floral scents of euglossine-pollinated plants are hypothesized to have evolved in response to the preexisting sensory biases of their male euglossine bee pollinators. However, this has never been investigated at the peripheral olfactory circuitry of distinct pollinating genera. Here, we present a comparative analysis using electroantennography (EAG) of males across the phylogeny of 29 euglossine bee species, among them Euglossa and Eulaema species. First, we tested whether antennal responses differ among different euglossine genera, subgenera and species. Secondly, we conducted a comparative phylogenetic analysis to investigate the macroevolutionary patterns of antennal responses across the euglossine bee phylogeny. We found that antennal response profiles are very unique on the species level and differ on the subgenus and the genus level. The differences can be explained by chemical compounds typically found in the floral scent bouquets of perfume flowers and specific compounds of species either pollinated by Euglossa (e.g., ipsdienol) or Eulaema bees (e.g., (−)-(E)-carvone epoxide). Also, we detected a phylogenetic signal in mean antennal responses and found that especially at the species level of our simulation the overall antennal responses exhibit greater disparity relative to a null model of pure Brownian-motion across the phylogeny. Altogether, our results suggest that (1) euglossine bee species exhibit species-specific antennal responses that differ among euglossine genera and subgenera, (2) antennal responses diverge early after speciation events, and (3) scent composition of perfume flowers evolved in response to pollinator-mediated selection imposed by preexisting sensory biases in euglossine bees.

Novelties in the secretory structures of three species of Gongora (Orchidaceae: Stanhopeinae)

The members of the Stanhopeinae (Orchidaceae) bear osmophores, which are related to pollination since they exude volatile lipids that attract euglossine bees. Gongora spp. are pollinated exclusively by euglossine bees. In view of the structural diversity found in the flowers of this genus and the lack of data on other foraging insects that visit these flowers, we elucidated aspects of the anatomy of floral secreting structures in the Stanhopeinae group, focusing on structures in Gongora jauariensis, Gongora pleiochroma and Gongora minax, species from the Amazon Rainforest. Secretory structures were analysed using light, scanning and transmission electron microscopy, and histochemical and phytochemical procedures. Osmophores, extrafloral nectaries and elaiophores were observed. The three species bear a structured nectary on the bract and osmophores on both the sepals and labellum hypochile. In G. minax, the labellum (hypochile) shows chemical and structural characteristics of elaiophore and osmophores, suggesting that it has both functions. We report interactions between foraging ants and nectaries of Gongora spp. for the first time. Interactions with ants attracted by the nectaries on the bracts are beneficial for orchids, as the ants help to protect their reproductive structures.

Orchid Bees (Hymenoptera: Apidae: Euglossini) in Seasonally Dry Tropical Forest (Caatinga) in Brazil

Euglossini bees are important Neotropical pollinators, but there is a lack in the knowledge about this fauna in dry tropical environments. The aims of this study were to evaluate the richness and abundance of euglossine bees in two fragments of seasonally dry tropical forest (Caatinga), as well as to assess the distribution of euglossine species richness in the Caatinga environment. Males were collected along 12 consecutive months, using traps with aromatic baits. The species richness (S=5) was lower than in rainforests and savannas. Euglossa cordata (L.) was the dominant species in the assemblage, representing 70% of the individuals. The highest abundance occurred in the rainy season. Euglossini fauna presents low local species richness in Caatinga areas, however the beta diversity is higher, since assemblages in different habitats have differences in species composition.