Little is known of the potential coevolution of flowers and bees in changing, biodiverse environments. Female solitary bees, megachilids and Centris, and their nest pollen provisions were monitored with trap nests over a 17-year period in a tropical Mexican biosphere reserve. Invasion by feral Apis (i.e. Africanized honey bees) occurred after the study began, and major droughts and hurricanes occurred throughout. Honey bee competition, and ostensibly pollination of native plants, caused changes in local pollination ecology. Shifts in floral hosts by native bees were common and driven by plant phylogenetics, whereby plants of the same families or higher taxa were substituted for those dominated by honey bees or lost as a result of natural processes.

This study documents the stingless bees' (Meliponinae) recent displacement in the Yucatan (Quintana Roo, Mexico) and the effects of human‐induced ecosystem disturbance on bee diversity. Point observations of flower‐visiting bees were made along transects in three communities with different degrees of human‐induced ecosystem disturbance. The community with the greatest anthropogenic disturbance had lower overall species richness of stingless bees and the highest degree of dominance of the Africanized honeybee (Apis mellifera scutellata), while the area with the most intact ecosystem had the highest diversity of stingless bees, though A. mellifera was still the dominant species. We observed aggressive competitive behavior involving physical attacks by A. mellifera against stingless bees, indicating that Africanized honeybees are adopting new behaviors to compete better with dominant native pollinator species.

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Tetragonisca angustula mating occurs during the virgin queen nuptial flight, usually in the presence of a drone congregation area (DCA). The presence of virgin queen pheromone is considered the trigger for DCA establishment, although this has not been demonstrated experimentally. We established meliponaries, in different habitats, with T. angustula virgin queens during the main drone reproduction period. Eight DCAs were observed in urban areas, and all established outside or near colonies containing at least one virgin queen. The accumulation of drones in the DCAs occurred from 08:00 to 18:00 h and over 3-35 days. The number of drones in DCAs ranged from 60 to 2,000. In field trials, drones were attracted to virgin queens and also, unexpectedly, to physogastric queens. Volatiles collected from both virgin and physogastric queens elicited strong electoantennogram (EAG) responses from drones. Virgin and physogastric queen volatiles were qualitatively similar, but quantitatively different, in chemical composition. The queen's abdomen was the principal source of these compounds. Isopropyl hexanoate (IPH), the most abundant compound in virgin queen volatiles and one of the most abundant in physogastric queen volatiles, was identified as one of the compounds that elicited EAG responses and was demonstrated to attract drones in a field test.

Using precise pollen species determination by conventional microscopic methods, accompanied by molecular genetic markers, we found bees collect GMO (genetically modified) soybean pollen and incorporate it in Yucatan honey. Honey comb samples from Las Flores, Campeche, Mexico, often contained soybean pollen. Pollen in honey was analyzed in nine samples; six contained substantial soy pollen and two tested positive for soybean GMO. Our analyses confirm field observations that honey bees, Apis mellifera, gather soybean pollen and nectar. The resultant risk for honey production in the Yucatán Peninsula and Mexico is evident in wholesale price reduction of 12% when GMO products are detected and honey consignments are rejected. Although this affects only 1% of current export honey (2011–2013) GMO soybean is an unacknowledged threat to apiculture and its economics in one of the world's foremost honey producing areas.

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We investigated pollen diets of Euglossa viridissima Friese and its recently described sibling species, Euglossa dilemma Bembé & Eltz, in a degraded dry forest locality near Merida, Yucatán, Mexico. Pollen samples were obtained from nests collected in the rainy season of three consecutive years (2006)(2007)(2008). Solanum sp. (Solanaceae), Physalis sp. (Solanaceae), Ocimum sp., Ocimum micranthum (both Lamiaceae), and Senna sp. (Fabaceae) were the dominant taxa, accounting for 88 % of pollen volume across species. Other important pollen taxa were Croton spp. (Euphorbiaceae), Ipomoea sp. (Convolvulaceae), Solanum torvum, Vigna sp. (Fabaceae), Sida sp. (Malvaceae), and Randia aculeata (Rubiaceae). The predominantly buzzpollinated family Solanaceae alone represented more than 77 % of total pollen volume. Multivariate analysis revealed significant effects of year but not of bee species on nest pollen composition. We conclude that pollen resources overlap substantially among these sibling species, with resource partitioning apparently absent or confined to periods of severe pollen scarcity.pollen provisions / resource partitioning / floral resource competition / acetolysis / pollen analysis