An article I wrote in July 2010
Colony Collapse Disorder (CCD) is the name given to the mysterious disappearance of honey bee colonies first reported in 2006.(1) It has caused 30-60 percent loss of honey bee colonies in United States, Europe and Asia. CCD induced bee death follows a very particular pattern – hives that had been active and productive one week were suddenly all-but empty the next – except for an abandoned queen and few loyal workers. The rest of the bee community is nowhere to be seen – presumed they fly off in different directions to point of exhaustion and death (perhaps to avoid infecting other bees and colonies). It was recently estimated that if such losses continued then the Western Honey Bee (Apis mellifera) would disappear from the planet by year 2020. In the western world honey bee is considered extremely important as it is the major pollinator for the modern agricultural industry.
The reason for such loss of honey bee colonies could not be determined despite intense research past few years. It was thought that myriad of factors may have been involved and that either alone or in synergy they affect honey bee immune system. Some of the implicated factors were pesticides, industrial farming, mobile phone signals, monoculture, GM food, bee nutrition and infection. Bee keepers themselves were most interested in a new kind of pesticide known as neonicotinoids, a class of neurotoxins that kills insects by attacking their nervous system. They alleged that the pesticides have disoriented and ultimately killed the bees. However, none of these above mentioned factors could clearly account for the CCD. For example fungus Nosema Ceranae was found in guts of dead insects in earlier studies performed in Spain. However, as it was found to be completely harmless it was not considered the cause.
Now a team of scientists from University of Montana and the US Army scientists working together have come up with a plausible reason for the honey bee loss. In their paper published in PloS One(2), they used extremely sophisticated new army equipment (mass spectrometry-based proteomics, MSP) that can detect all types of protein specimens from bee remains, it detected both Nosema fungus but also DNA-virus known as invertebrate iridesecent virus (IIV) in all collapsed colonies. Like Nosema fungus, the IIV by itself does not seem to do bees any harm and is actually quiet prevalent in bee colonies. When only when the two come together in the bee gut that they become fatal.
The scientists found this combination (fungus/virus) in every killed colony group they studied. But they acknowledge that they don’t know if the Nosema fungus and IIV virus are a marker, cause or consequence of CCD. In any case, they have presented a very strong link with CCD, and this hopefully will lead to further research.
The major question remains as this study does not tell us why bees leave the hive before they die. The lead scientist, Jerry Bromenshenk of University of Minnesota, theorises that bees complex navigation system may have been damaged by this infection or worse still these pathogens trigger some sort of bee ‘insanity’.(3) It is now thought that focusing efforts on eradicating either the fungus or the virus would fix the CCD problem. Anti-fungals, that exist already, could be used to eradicate the fungus and see if it can cure the bees.
Other scientists are questioning the new study as research has shown that pesticides affect bees in multiple ways with neonicotinoids affecting bees’ learning and memory. They say that the new paper showed a correlation only, and a correlation is not the same as a cause, and that this study failed to ask the underlying question “Why are colonies dying? Is it because they’re getting weak? People who have HIV don’t die of HIV. They die of other diseases they get because their immune system is greatly weakened, making them susceptible.” In other words, pesticides could weaken the bees – and then the virus/fungus combination kills them off. This they say is not explored in this study.
Another news report shed a light on the links of the lead author that may make people question the findings of this study.(4) The lead author, Jerry Bromenshenk, received a grant within last few years from Bayer Crop Science, a leading manufacturer of pesticides like neonicotinoids. As pesticides are one of the leading contenders for the cause of CCD, this constitutes a potential conflict of interest that is not noted in the paper. It is also thought that Bromenshenk’s company, Bee Alert Technology, which develops hand-held acoustic scanners that use sound to detect various bee ailments, will profit from a finding that disease, and not pesticides, is harming bees.
1. van Engelsdorp D, Hayes J, Underwood RM, Pettis J. A survey of honey bee colony losses in the U.S., fall 2007 to spring 2008. [Internet]. PLoS ONE. 2008 ;3(12):e4071.Available from: http://www.ncbi.nlm.nih.gov/pubmed/19115015
2. Bromenshenk JJ, Henderson CB, Wick CH, Stanford MF, Zulich AW, Jabbour RE, et al. Iridovirus and Microsporidian Linked to Honey Bee Colony Decline [Internet]. PLoS ONE. 2010 Oct ;5(10):e13181.Available from: http://dx.plos.org/10.1371/journal.pone.0013181
3. Honeybee Killer Found by Army and Entomologists – NYTimes.com [Internet]. Available from: http://www.nytimes.com/2010/10/07/science/07bees.html
4. What a scientist didn’t tell the NY Times on honeybee deaths – Oct. 8, 2010 [Internet]. Available from: http://money.cnn.com/2010/10/08/news/honey_bees_ny_times.fortune/index.htm