Colony collapse disorder has been decimating bees for several years, but explanations have been hard to come by. After some spurious claims about cell phones causing the problem, researchers began identifying factors that did create problems for the health of bees, including infections, insecticides, and agricultural practices. The problem is that all of these seemed connected to colony collapse, which suggested the cause was likely to be complex.

Now, some researchers may have cut through the complexity. They've found that a common insecticide causes changes in the immune system of insects, which in turn leaves them more vulnerable to infection. And they've begun the process of determining how those immune changes come about on the molecular level.