"A new method for monitoring the decline in bee populations may prove a useful tool in much-needed conservation efforts. It requires only a few hundred pan traps: bright shallow bowls partly filled with soapy water or propylene glycol."
"When United Nations experts noticed that crop production was flagging in seven countries around the world, from Brazil to Nepal, they contacted Gretchen LeBuhn, an associate professor at San Francisco State University who studies bees.
'The U.N. thought that the problem might be tied to a decline in bee populations,' Dr. LeBuhn said. 'I was hired to see if it would be feasible to monitor this decline.'
Her results, published in the most recent issue of Conservation Biology, outline the new monitoring method, which is remarkably cheap and efficient for tracking national, regional or global bee populations. At any of these scales, the pan traps can do the job at a cost of less than $2 million over five years."