Bumblebees of the subgenus Psithyrus (known as 'cuckoo bumblebees', and formerly considered a separate genus) are brood parasites, sometimes called kleptoparasites, in the colonies of other bumblebees, and have lost the ability to collect pollen.ueen and worker bumblebees can sting. Unlike in honeybees, a bumblebee's stinger lacks barbs, so the bee can sting repeatedly without injuring itself; by the same token, the stinger is not left in the wound. Bumblebee species are not normally aggressive, but may sting in defence of their nest, or if harmed.
STEM CELLS SAVE LIVES. For decades, doctors have harnessed the unique ability of stem cells to treat leukemia and genetic blood diseases. But now, researchers are discovering that these cells have the power to heal, to fight disease, and to regenerate damaged or aging tissue throughout the body. To fully understand why they hold the potential to change your childâs medical future, get to know more about stem cells.
A stem cell is a type of cell that is nonspecific in its function; in contrast, for instance, to a heart or brain cell, which is functionally specific. There are two major sources of stem cells: embryonic stem cells and non-embryonic stem cells.Embryonic stem cells are obtained from 5- to 12-day old embryos.Although removal of a stem cell from an embryo kills the embryo, the stem cells are valued for their potential to produce any type of cell.hus, the heart of the stem-cell controversy centers on the aforementioned fact that the extraction of stem cells from 5- to 12-day embryos kills the embryo. But thatâs not the only issue: In addition, stem cells derived from an embryonic human may, in turn, reject the person who receives them.