We've suspected for quite some time now that cutting-edge insecticides were responsible for the catastrophic hive crashes that are inflicting honey bee populations. But recent evidence suggests that this may not be the case — instead, Colony Collapse Disorder is the result of a highly contagious virus that's being transmitted by parasitic mites.
Early last year we reported that clothianidin, an insecticide sold in the USA, disrupts the nervous system of insects, leading it to be a prime suspect in the mass death of honey bees. And just a few months ago we reported on a Science article reaffirming the suspicion that insecticides, particularly neonicotinoids, may be responsible.
But new research coming out of Hawaii suggests that this may not be the case.
It turns out that the parasitic Varroa mite - long known to torment honey bee populations - may be the culprit behind CCD. Or more accurately, it's the Deformed Wing Virus (DWV) that's being transmitted by these mites that's causing all the trouble.
The virus is transmitted between bees when they feed or mate. It's particularly nasty in that it enters into a bee's bloodstream, creating a new viral transmission route that bypasses many of the bees' natural defensive barriers. DWV, which has only 9 genes, is similar in structure to polio and the foot-and-mouth virus.
The research, which was conducted in Hawaii by researchers at Sheffield University, the Marine Biological Association, FERA and University of Hawaii, showed that Varroa increases the frequency of DWV in bee colonies from 10% to an astounding 100%. Accompanying this is a million-fold increase in the number of virus particles infecting each honey bee and a massive reduction in viral strain diversity. It's this combination of factors that is leading to the emergence of a single virulent DWV strain.
Disturbingly, the researchers are discovering that the mite is permanently altering the honey bee viral landscape in Hawaii, a trend that they believe is being mirrored across other parts of the planet. Their findings suggest that this could be a key factor in explaining the prevalence and devastation of colony collapse disorder around the world.
Eurkealert. Image via Shutterstock / LilKar.