Here's an informative article on the demise of honeybees. Israeli Acute Paralytic Virus is thought to have been imported with seemingly healthy Australian bees by American beekeepers in 2004. A healthy bee population is essential to pollinization of food crops as well as ornamental plants, so the problem is being aggressively researched. Pesticide exposure, environmental stress, bacterial and fungal diseases and a parasitic mite are also thought to have contributed to what has affected from 50 to 90% of U.S. commercial honey bee colonies over the past several years.
In the meantime, there are other bee species that are effective pollinators, and there are ways to encourage them to make their hives in your garden areas. I've been researching the topic and will address it further in the fall, when orders are taken for spring delivery of the bees. I'll include resources and also links to makers of the most effective types of bee houses.
For this spring, be sure plenty of early-blooming plants are located in the vicinity of your fruit trees when they come into flower, to ensure good yield. Funded by the Haagen Daz Corporation (which credits honey bees for almost half of their 60 ice cream flavors!) The Penn State University Master Gardeners Program offers homeowners and professionals their guidelines for creating bee-friendly environments.
Note: Honey bees are NOT aggressive stingers.