They claim they are still losing between 30% - 90% of their hives each year. Billions of honeybees have died in the US since CCD became apparent in the winter of 2006-2007. Honeybees are used to pollinate more than 130 crops in the US worth over $15 billion, and teams of scientists have been working to solve their mysterious disappearance.
There are still many theories floating around, and the beekeepers I've spoken to have different strategies for establishing successful hives. An organic keeper I spoke to months ago recommended a minimum of 6 hives, and said most beekeepers feed sugar in the fall which is completely wrong. Our beekeeper thinks current research points to having less than 5 hives to mimic natural habitat more closely and try and keep mite populations in check and said feeding sugar water in the fall might be necessary if we have a terrible summer and there are not that many natives flowering as they might need the extra food to sustain them through another potentially bad winter. I can see the sense in this, though am hoping the summer is terrific and all our autumn flowering wild grasses and natives make sugar water unnecessary.
An early study published in the journal Science in 2007 showed a strong correlation between CDC and a pathogen called Israeli acute paralysis virus, or IAPV. Scientists screened honeybees collected from colonies infected with CCD with honeybees from healthy hives and found the IAPV virus, which is transmitted by the varroa mite, in all samples from the CCD colonies. Jeffrey Pettis, an entomologist at the USDA's Agricultural Research Service stressed this was only a strong correlation, not a proven cause-and-effect connection and the research did not prove that IAPV was actually the cause of CCD.
A recent study conducted by researchers at Washington State University posits a combination of toxic chemicals and pathogens are probably to blame. "One of the first things we looked at was the pesticide levels in the wax of older honeycombs," researcher Steve Sheppard said.
The researchers acquired used hives from the U.S. Department of Agriculture, finding that they had "fairly high levels of pesticide residue." When bees were raised in these hives, they had "significantly reduced longevity," the researchers said.
Prior research by scientists from Pennsylvania State University found unprecedentedly high levels of two pesticides in every sample of honeycomb or foundation wax tested, as well as lower levels of 70 other pesticides. The pesticides found in the highest concentrations were fluvalinate and coumaphos, used to eradicate the bee pest varroa mites, which have themselves been suggested as a cause of colony collapse.
"We do not know that these chemicals have anything to do with colony collapse disorder, but they are definitely stressors in the home and in the food sources," said Penn State researcher Maryann Frazier. "Pesticides alone have not shown they are the cause of [colony collapse disorder]. We believe that it is a combination of a variety of factors, possibly including mites, viruses and pesticides."
The Washington State researchers uncovered another potential cause, which likely interacts with chemicals to contribute to colony collapse: the pathogen Nosema ceranae, which entered the United States around 1997 and has since spread to bee hives across the country. The pathogen attacks bees' ability to process food and makes them more susceptible to chemicals and other infections.
"What it basically does is it causes bees to get immune-deficiency disorder," said beekeeper said Mark Pitcher of Babe's Honey. "So it's actually causing the bees to almost get a version of HIV." So far our new bee colonies seem to be alive and buzzing, with bees swarming over the nepeta and herbs in the garden and will be fat and healthy enough to be nursed thorough whatever the winter throws at us.