Many blame neonicotinoid insecticides -- a new type of insecticide related to nicotine that attacks the nervous system of the insects and is deemed less toxic than organophosphates -- although not everyone agrees. Some scientists complain that experiments to date have been restricted to laboratories and do not replicate the real world.
The spotlight has also recently swung onto the varroa mite, which is omnipresent in honeybee colonies but seems to become a major threat when those bees have been weakened and made vulnerable by some other factor.
"Varroa is probably the single most important thing affecting honeybee populations. If you talk to French beekeepers, they will tell you that pesticides killed their bees. But it is pesticides and varroa. If you talk to the Spanish bee researchers, they will tell you that a gut parasite is killing their bees. But it is the gut parasite and varroa," said Norman Carreck, science director of the International Bee Research Association at the University of Sussex.
But one fact that bee experts all agree on is that while bees, particularly honeybees, are very adaptable creatures in normal circumstances, they are highly vulnerable to extremes of weather, particularly downpours and flooding.That is interesting. This spring was definitely an earlier one, but not having a real winter also makes bugs a bigger issue. I think that may impact temperate growing areas pretty significantly.
"Weather has a huge impact on honeybee survival. What seems to be happening is that we in the U.K. are getting more extremes of weather at either end of our normal range. Whether that is due to climate change is an interesting question," Tim Lovett, director of public affairs at the British Beekeepers' Association, said last month at the annual Hampton Court Flower Show about 10 miles southeast of central London.
"The wrong weather at the wrong time can be very bad for bees," he added. "One of the major causes of loss among honeybees in the spring is starvation. There are suddenly thousands of new mouths to feed. If they wake early and the plants are still asleep, then there is trouble. Likewise, if the plants wake early and the bees are still asleep and miss the first flush, then there can also be trouble."
Botanist Sandra Bell at the world-renowned Kew Gardens in London said flowering times have advanced by several weeks over the past half-century. While it is hard to pin that on climate change, it is certainly one of the effects to be expected, according to the models.