Visualizing Environmental Science

EnviroDiscovery

Bee Colonies Under Threat

Deaths resulting from viruses, including the Israeli acute-

paralysis virus (IAPV), which can be spread by mites

Bees are necessary for the pollination of a variety of

important crops, many of which—nearly 100—are potentially

threatened by these bee declines. The demand on bees to

pollinate crop species has increased even as the number

of bee colonies maintained by keepers has dropped. Some

agricultural researchers believe that the added stress

placed on bee colonies as they are transported to carry out

pollination has increased the susceptibility of these colonies

to health threats by compromising bees’ immune systems.

Recent research indicates that improving hive hygiene can help

prevent CCD.

Since late 2006, many U.S. beekeepers have experienced major
losses in their bee colonies, 30 to 90 percent of total individuals.
Similar bee disappearances have occurred in other countries,
resulting in losses of millions of bees worldwide. These sudden
declines, known in the United States as colony collapse disorder
(CCD), are thought to be triggered by a complex mix of factors.
Researchers are investigating three major potential causes of CCD:

The negative effects of pesticides including—according to

recent research—some of the most widely used insecticides

in the world

Damage caused by pathogens or parasites, such as Varroa

and tracheal mites, and a parasitic fly recently reported to

be taking over the bodies of Northem California honeybees

118 CHAPTER 5 How Ecosystems Work

CNImaging/NewsCom

Two fruit growers hand pollinate pear trees in Yongchuan, Chongqing, China, a region
where local bee populations have vanished.