Foraging by Male and Female Solitary Bees with Implications for Pollination

Both male and female solitary bees visit flowers for rewards. Sex related differences in foraging efficiency may also affect their probability to act as pollinators. In some major genera of solitary bees, males can be identified from a distance enabling a comparative foraging-behavior study. We have simultaneously examined nectar foraging of males and females of three bee species on five plant species in northern Israel. Males and females harvested equal nectar amounts but males spent less time in each flower increasing their foraging efficiency at this scale. The overall average visit frequencies of females and males was 27.2 and 21.6 visits per flower per minute respectively. Females flew shorter distances increasing their visit frequency, relative foraging efficiency and their probability to pollinate. The proportion of conspecific pollen was higher on females, indicating higher floral constancy and pollination probability. The longer flights of males increase their probability to cross-pollinate. Our results indicate that female solitary bees are more efficient foragers; females seem also to be more efficient pollinators but males contribute more to long-distance pollen flow.     

The C. elegans developmental fusogen EFF-1 mediates homotypic fusion in heterologous cells and in vivo

During cell-cell fusion, two cells' plasma membranes merge, allowing the cytoplasms to mix and form a syncytium. Little is known about the mechanisms of cell fusion. Here, we asked whether eff-1, shown previously to be essential for fusion in Caenorhabditis elegans, acts directly in the fusion machinery. We show that expression of EFF-1 transmembrane protein drives fusion of heterologous cells into multinucleate syncytia. We obtained evidence that EFF-1-mediated fusion involves a hemifusion intermediate characterized by membrane mixing without cytoplasm mixing. Furthermore, syncytiogenesis requires EFF-1 in both fusing cells. To test whether this mechanism also applies in vivo, we conducted genetic mosaic analysis of C. elegans and found that homotypic epidermal fusion requires EFF-1 in both cells. Thus, although EFF-1-mediated fusion shares characteristics with viral and intracellular fusion, including an apparent hemifusion step, it differs from these reactions in the homotypic organization of the fusion machinery.