title: Dietary traces of neonicotinoid pesticides as a cause of population declines in honey bees: an evaluation by Hill's epidemiological criteria.
abstract: BACKGROUND
  Honey bees are important pollinators of both crops and wild plants. Pesticide regimes that threaten their sustainability should therefore be assessed. As an example, evidence that the agricultural use of neonicotinoid pesticides is a cause of the recently observed declines in honey bees is examined. The aim is to define exacting demographic conditions for a detrimental factor to precipitate a population decline, and Hill's epidemiological 'causality criteria' are employed as a structured process for making an expert judgement about the proposition that trace dietary neonicotinoids in nectar and pollen cause population declines in honey bees.
  
  
  RESULTS
  In spite of the absence of decisive experimental results, the analysis shows that, while the proposition is a substantially justified conjecture in the context of current knowledge, it is also substantially contraindicated by a wide variety of circumstantial epidemiological evidence.
  
  
  CONCLUSIONS
  It is concluded that dietary neonicotinoids cannot be implicated in honey bee declines, but this position is provisional because important gaps remain in current knowledge. Avenues for further investigations to resolve this longstanding uncertainty are therefore identified.
authors.affiliation: College of Life and Environmental Sciences, University of Exeter, Hatherly Laboratories, Exeter, UK. j.e.cresswell@ex.ac.uk
authors.forename: James E
authors.initials: JE
authors.lastname: Cresswell
authors.forename: Nicolas
authors.initials: N
authors.lastname: Desneux
authors.forename: Dennis
authors.initials: D
authors.lastname: vanEngelsdorp
mesh_terms: D000818:Animals; D001516:Bees / Q000502:physiology*; D004032:Diet / Q000009:adverse effects*; D016021:Epidemiologic Studies; D009538:Nicotine / Q000737:chemistry*; D010573:Pesticide Residues / Q000009:adverse effects* / Q000737:chemistry*; D011157:Population Dynamics
chemical_list: D010573:Pesticide Residues; D009538:Nicotine