The Challenge: Assessment of risks posed by systemic insecticides to hymenopteran pollinators: New perception when we move from laboratory via (semi-)field to landscape-scale testing? Reported declines in overwinter survival of bee colonies encouraged many researchers to investigate the causative factors behind the bee health problem with a particular focus on neonicotinoid insecticides. Naturally, 2 decades of intensive scientific research and dispute have failed to provide enough evidence to reach a consensus in the scientific community on the effects of exposure to systemic residues of neonicotinoid insecticides on insect pollinator populations. Diverse sublethal effects including lethal effects after repeated exposure have been reported from laboratory studies that applied different doses of those insecticides to individual pollinators via an artificial exposure pathway. In contrast, no relevant effects to honeybees at the colony level were found in a large number of semi-field and field studies where bees were exposed to environmentally realistic concentrations and exposure pathways of neonicotinoid insecticides. In addition, evidence from eco-epidemiological studies, which evaluated the effects of exposure to neonicotinoid insecticides in representative agricultural landscapes does not support the hypothesis of a causal relationship between exposure to systemic residues of neonicotinoid insecticides and adverse effects in bees. We asked 5 authors to share their views regarding the conclusiveness of studies that investigated the effects of neonicotinoid insecticides on honeybee colonies in a representative agricultural landscape context and how to make
the best use of the evidence in an authorization process. With Responses from Academia, Industry, Regulatory Perspective from the US and Australia
