A new study by John Bryden of Royal Holloway University of London and his colleagues supports the current theory that colony collapse is likely a result of a number of stressors. Scientific American Climate Change & Environment briefings reports this month that Bryden modeled stresses on bees. “The model accurately predicted the fate of 16 experimental colonies of bumbles (Bombus terrestris), of which half were exposed to a neonicotinoid pesticide at levels that do not kill bees but do reduce their ability to learn and gather food.”
The full report (“Chronic Sublethal Stress Causes Bee Colony Failure”, Ecology Letters, (2013) 15: 1463-1469) states, “Recent evidence has indicated that many environmental stressors can affect bees even when they do not cause direct morality (so called sublethal impact).” It is the burden of these impaired hive members that compounds the stress on the hive, bringing it to the tipping point.
According to the report, the stressor must be present for several weeks before it can be considered a factor. At first the colony will continue to grow. However, as the ratio of impaired to unimpaired hive members grows, the colony will begin to fail. The overall health of the hive to start is a significant factor in how successful the hive will be in weathering the introduction of weakened members.
Experts such as Flottum, Spivak, Schacker, and Erickson have also reported that there are significant stressors at work in the world of pollinators. Bees are shipped across the country to fertilize crops. Bees are forced to exist in areas that are pollen desserts. The net effect on bees is that they are not in a position to weather a significant negative event that significantly impacts the inner workings of the hive.