VOX By Brad Plummer March 9, 2015
Honeybees and wild bees alike are mysteriously dying off all over the world. And scientists have long struggled to pinpoint why, exactly, that is.
Some experts cite diseases and invasive parasites like the Varroa destructor mite, introduced from Asia and afflicting US honeybees. Others point to a new class of pesticides called neonicotinoids that mess with the nervous systems of insects. Still others blame the loss of wild habitat, as diverse flowers are replaced by suburban lawns or farms with just a few crops, impoverishing bee diets.
But the best explanation may be that it's not just one thing hurting the bees — it's lots of different things working together, often in unexpected ways.
In a recent review paper for Science, a team of researchers argue that the combination of modern stresses facing bees seem to be much deadlier than is often appreciated. Pesticides alone might not be enough to wipe out bee colonies, but studies have shown that they can make bees more susceptible to invasive parasites. Poor nutrition can lead bumblebees to succumb to disease. Fungicides and pesticides are more potent together than in isolation. This graphic from the paper details just a few known interactions:
Now, it might seem totally obvious that chronic exposure to lots of different stresses would be bad for the bees. But surprisingly...