The week of July 16 is being celebrated as National Pollinators Week in an effort to bring more awareness to the integral role that pollinators such as bees, birds, and the other flying creatures play in the life cycles of an estimated 75 percent of the world’s crop varieties and 35 percent of total crop production. The occasion is also a time to reflect on the current understanding of colony collapse disorder (CCD), the phenomenon causing a spike in die-offs of honey bee populations around the world over the past decade. One of the biggest developments in CCD research from the past year has been a study from the Harvard School of Public Health on the effects of neonicotinoid pesticides on bee populations. The study found that, while non-lethal doses of these pesticides would not seem to harm the bees during spring and summer, they had dramatic effects on the bees during winter. Six out of 12 pesticide-treated bee colonies in the study abandoned their hives after winter and died off, while only one out of six of the non-pesticide colonies died off — and that was from a different disease that killed the bees inside their hive. One of the trademarks of CCD is a low number of dead bees left behind, with most abandoning the hive to die elsewhere. While research is still being done to clearly define the cause of CCD, at this point believed to be the cumulative effect of numerous stressors on bees, the Harvard study’s authors concluded that their experiment singled out neonicotinoid pesticides as the leading cause of the problem. At the same time, neonicotinoids are facing more legal scrutiny on both sides of the Atlantic. Last August, the U.S. Environmental Protection Agency introduced mandatory labels on neonicotinoid pesticides that warn users to be wary of harming pollinators and advising them not to spray under certain conditions during which pollinators are most likely to be present. In December 2013, a two-year ban on neonicotinoids went into effect in Europe in order to study how well European bee populations fare in the absence of the pesticides. The U.S. EPA will be keeping a close eye on how that ban plays out. “Based on currently available data, the EPA’s scientific conclusions are similar to those expressed in the EFSA [European] report with regard to the potential for acute effects and uncertainty about chronic risk,” EPA stated. “However, the EFSA report does not address risk management, which, under U.S. federal law, is a key component of the EPA’s pesticide regulatory scheme.” Chemical companies fought the European ban, saying that it placed an unfair blame on pesticides when evidence suggested a number of other factors, such as viruses and parasites, played into CCD. Bee experts aren’t all ready to place the blame squarely on pesticides, either. As more research time focuses on CCD, more researchers are coming to the conclusion that it’s caused by a complex synergy of factors, said Dr. Gene Robinson, director of the Institute for Genomic Biology and the Swanlund Chair of Entomology at the University of Illinois. “The simple fact of the matter is that no single factor can explain the occurrence, distribution and severity of colony collapse disorder,” Robinson said. Researchers are increasingly designing studies that account for multiple stressors on bees — not a simple feat to achieve in a controlled study environment. Measuring one effect really well is difficult enough, Robinson noted. At this point, Robinson said he viewed insecticides as receiving too much of the blame. He cautioned against focusing solely on chemicals when pathogens, parasites and environmental changes have shown to have a significant effect on CCD. “Colony collapse disorder can be regarded as a warning sign for all of our interactions with the environment and the species that are important to us,” Robinson said. “There are a variety of different factors in different combinations that can all have serious effects.” And, while conducting research is expensive and public attention may wane until the next dire news of massive die-offs emerges, Robinson said it’s incredibly important to continue understanding CCD and what it could mean for our environmental interactions on a bigger scale. “Using honey bees as canaries in the coal mine, what does this say about other species?” he asked.