Mr Richards said that bees are under “great threat” from pesticides, which he believes should not be used because there are “well-documented alternatives”
The systemic nature of the problem makes it complex, but not impenetrable. Scientists know that bees are dying from a variety of factors—pesticides, drought, habitat destruction, nutrition deficit, air pollution, global warming and more. Many of these causes are interrelated. The bottom line is that we know humans are largely responsible for the two most prominent causes: pesticides and habitat loss.
Worker bees (females) live about six weeks in summer and several months in the winter. Colonies produce new worker bees continuously during the spring and summer, and then reproduction slows during the winter. Typically, a bee hive or colony will decline by 5-10 percent over the winter, and replace those lost bees in the spring. In a bad year, a bee colony might lose 15-20 percent of its bees.
In the U.S., winter losses have commonly reached 30-50 percent, in some cases more. In 2006, David Hackenberg — a bee keeper for 42 years — reported a 90 percent die-off among his 3,000 hives. U.S. National Agricultural Statistics show a honey bee decline from about 6 million hives in 1947 to 2.4 million hives in 2008, a 60 percent reduction.
The number of working bee colonies per hectare provides a critical metric of crop health. In the U.S. — among crops that require bee pollination — the number of bee colonies per hectare has declined by 90 percent since 1962. The bees cannot keep pace with the winter die-off rates and habitat loss.
Content from article here: https://www.greenpeace.org/usa/sustainable-agriculture/save-the-bees/