A honeybee killer is on the loose in America—and last September, entomologists inched closer to fingering a suspect. The vanishing bee syndrome, dubbed colony collapse disorder (CCD), has wiped out 50 to 90 percent of bee colonies in 35 states and been blamed on everything from pesticides to virulent new pathogens. However, a genetic analysis of the microorganisms harbored by the stricken bees has now strongly linked CCD to Israeli acute paralysis virus (IAPV), an infectious agent that triggers shivering wings, paralysis, and death. But no one knows whether IAPV is a cause or a symptom of CCD. In fact, many researchers believe it may simply be an opportunistic infection that swoops in on bees already weakened by stress, parasitic mites, and the rigors of traveling to pollinate crops.
Physician Ian Lipkin of Columbia University and entomologist Diana Cox-Foster of Penn State analyzed separate colonies within beekeeping operations affected by CCD as well as colonies in operations unaffected by it, taking samples of genetic material from more than 1,200 bees. They also took a sample of healthy bees from Australia and four samples of royal jelly from bees in China. Lipkin then used a rapid genome-sequencing technique to identify RNA from a variety of bacteria, fungi, and viruses. He found that if four pathogens, including IAPV, were present, the colonies were invariably hit by CCD. Most significantly, IAPV was present in 25 out of 30 CCD-affected colonies, but in only one of the healthy U.S. operations.
Because the symptoms of IAPV alone don’t match those of CCD, in which bees simply abandon the hive and disappear, researchers believe still other factors are involved. IAPV appeared in the Australian bees, for instance, but those bees have not succumbed to CCD. Interestingly, neither are they infected by varroa mites—the tiny, immunity-weakening parasites rampant in American hives. “Even before CCD, the bees were in trouble; there was a significant amount of mortality due to the varroa mites,” Cox-Foster explained. “So having a new virus coming in appears to cause an increased wave of mortality on top of that. Part of our fear here is that this is the straw that broke the camel’s back.”
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