November 10, 2011
The pollinator crisis: What's best for bees Pollinating insects are in crisis. Understanding bees' relationships with introduced species could help. By Sharon Levy www.nature.com Bees thrum among bright red blossoms on a spring day on Mount Diablo, near San Francisco Bay. Alexandra Harmon-Threatt, a young ecologist just finishing her doctorate at the University of California, Berkeley, lovingly identifies an array of native pollinators. She points out three species of bumblebee, each with a unique pattern of black and yellow stripes. There are bee-flies, members of the fly family covered in soft brown fur, which look and act like bees. Among the native insects are plenty of honeybees (Apis mellifera), the species raised by beekeepers worldwide and introduced to the Americas by English settlers in the seventeenth century. All these insects are drawn to a clump of red vetch (Vicia villosa), an invasive weed. Just down the road is a patch of native lupins, laden with purple blosso...