Extensive research in Hawaii has shown that a major cause of so-called colony-collapse disorder, which has sharply reduced bee populations in many parts of the world, is related to the spread of the parasitic varroa mite. Scientists at the University of Sheffield in England were able to track the arrival and spread of the varroa mite, Varroa destructor, on Oahu Island in Hawaii. Within a year of the blood-sucking mite’s arrival in 2007, 65 percent of the 419 bee colonies on Oahu were wiped out, according to the research, published in the journal Science. The following year the mites reached the big island of Hawaii and devastated bee colonies there, the study said. The Sheffield scientists said the mites spread a devastating ailment called deformed wing virus, which rapidly spread through bee colonies, killing nearly all the bees. The scientists said other factors also may be playing a role in the collapse of bee colonies worldwide, including the use of pesticides and the loss of flowering plants.