DEFRA also reviewed the body of evidence on neonicotinoids and concluded that, although there might be “rare effects of neonicotinoids on bees in the field”, these do not occur under normal circumstances.
Experts lined up to criticize the field study. Neuroscientist Christopher Connolly of the University of Dundee, UK, who has studied the effect of neonicotinoids in bee brains, says that the control colonies themselves were contaminated with the pesticides, and that thiamethoxam was detected in two of the three bee groups tested, even though it was not used in the experiment. Goulson agrees, saying of the study:“In many ways, it was appalling.” No one from DEFRA was available to talk to Nature.
Goulson and others say that intensive environmental monitoring of neonicotinoids and long-term field studies of their effects are sorely needed. He points to a 2012 study that found neonicotinoids in dandelions growing near treated crops, suggesting that the pesticides can spread from their intended target. “This debate has focused very heavily on bees. Perhaps we’re missing a slightly bigger picture,” he says. “For 20 years we’ve been using neonicotinoids without really assessing what impact they might be having in the wider environment.”