may worsen as a result of climate change, scientists say. In a paper published online this week by the Proceedings of the National Academy of Sciences, researchers describe the results of their study of caterpillar parasitism. The team found that as climatic variability increased, the frequency of parasitism against caterpillars decreased. This supports the idea that fluctuations in climate are affecting the behavior of caterpillars and other pests, which, in turn, is disrupting the ability of wasps and other insects that parasitize the caterpillars to track their prey--and thus keep their populations in check.