PHILADELPHIA — A mysterious disease is killing off U.S. honeybees, threatening to disrupt pollination of a range of crops and costing beekeepers hundreds of thousands of dollars, industry experts said on Monday. Beekeepers in 22 states have reported losses of up to 80 percent of their colonies in recent weeks, leaving many unable to rent the bees to farmers of crops such as almonds and, later in the year, apples and blueberries. ‘It’s unusual in terms of the widespread distribution and severity,’ said Jerry Bromenshenk, a professor at the University of Montana at Missoula and chief executive of Bee Alert Technology, a company monitoring the problem. Dave Hackenberg, a Pennsylvania beekeeper who reported the so-called Colony Collapse Disorder to researchers at Pennsylvania State University in November, said he had lost about 2,000 hives, which can each contain around 50,000 bees during the summer months. He estimated that he will lose as much as $350,000 after accounting for lost income and the cost of replacing bees. Researchers from state and federal agriculture agencies have been frustrated in their search for a cause because affected hives are often empty except for the queen and a few bees. […]