Towards a molecular definition of worker sterility: differential gene expression and reproductive plasticity in honey bees

We show that differences in the reproductive development of honey bee workers are associated with locus-specific changes to abundance of messenger RNA. Using a cross-fostering field experiment to control for differences related to age and environment, we compared the gene expression profiles of functionally sterile workers (wild-type) and those from a mutant strain in which workers are reproductively active (anarchist). Among the set of three genes that are significantly differentially expressed are two major royal jelly proteins that are up-regulated in wild-type heads. This discovery is consistent with sterile workers synthesizing royal jelly as food for developing brood. Likewise, the relative underexpression of these two royal jellies in anarchist workers is consistent with these workers’ characteristic avoidance of alloparental behaviour, in favour of selfish egg-laying. Overall, there is a trend for the most differentially expressed genes to be up-regulated in wild-type workers. This pattern suggests that functional sterility in honey bee workers may generally involve the expression of a suite of genes that effectively ‘switch’ ovaries off, and that selfish reproduction in honey bee workers, though rare, is the default developmental pathway that results when ovary activation is not suppressed

Potential pollinators of Comolia ovalifolia DC Triana (Melastomataceae) and Chamaecrista ramosa (Vog.) H.S. Irwin and Barneby var. ramosa (Leguminosae-Caesalpinioideae), in restinga, Bahia, Brazil

Comolia ovalifolia DC Triana (Melastomataceae) and Chamaecrista ramosa (Vog.) H.S. Irwin and Barneby var. ramosa (Leguminosae - Caesalpinioideae) are tropical plant species found in restinga (herbaceous-shrubby, sandy costal ecosystems). They have flowers with poricidal anthers and are pollinated by bees. The study sought to analyse potential pollinators of both plants during visits to their flowers in a restinga area in Bahia. The flowering displayed by both species was considered continuous and long duration, constantly providing pollen to floral visitors. C. ovalifolia was visited by 17 species of bees and C. ramosa by 16 species, predominantly from the Apidae family (with a similarity index of 74%). The behavior displayed by these visiting bees was of vibrating anthers. The small-sized Euglossa sp. Latreille, 1802 and Florilegus similis Urban, 1970 bees played less of a role as pollinators, since they rarely touched the flower stigma during harvests and were thus considered opportunist visitors or casual pollinators. Centris decolorata Lepetier, 1841 (= C. leprieuri) and Xylocopa subcyanea Perez, 1901 are large bees and were considered efficient pollinators of C. ovalifolia and C. ramosa because of the higher frequency and constancy of their visits, and their favourable behaviour and size for pollen transfer between flowers, which guarantees the survival of these native restinga plant species