title: Reconciling laboratory and field assessments of neonicotinoid toxicity to honeybees.
abstract: European governments have banned the use of three common neonicotinoid pesticides due to insufficiently identified risks to bees. This policy decision is controversial given the absence of clear consistency between toxicity assessments of those substances in the laboratory and in the field. Although laboratory trials report deleterious effects in honeybees at trace levels, field surveys reveal no decrease in the performance of honeybee colonies in the vicinity of treated fields. Here we provide the missing link, showing that individual honeybees near thiamethoxam-treated fields do indeed disappear at a faster rate, but the impact of this is buffered by the colonies' demographic regulation response. Although we could ascertain the exposure pathway of thiamethoxam residues from treated flowers to honeybee dietary nectar, we uncovered an unexpected pervasive co-occurrence of similar concentrations of imidacloprid, another neonicotinoid normally restricted to non-entomophilous crops in the study country. Thus, its origin and transfer pathways through the succession of annual crops need be elucidated to conveniently appraise the risks of combined neonicotinoid exposures. This study reconciles the conflicting laboratory and field toxicity assessments of neonicotinoids on honeybees and further highlights the difficulty in actually detecting non-intentional effects on the field through conventional risk assessment methods.
authors.affiliation: INRA, UR406 Abeilles et Environnement, 84914 Avignon, France UMT Protection des Abeilles dans l'Environnement, Site Agroparc, 84914 Avignon, France mickael.henry@paca.inra.fr.
authors.forename: Mickaël
authors.initials: M
authors.lastname: Henry
authors.affiliation: UMT Protection des Abeilles dans l'Environnement, Site Agroparc, 84914 Avignon, France Terres Inovia, Centre de Grignon, Avenue Lucien Brétignières, 78850 Thiverval Grignon, France.
authors.forename: Nicolas
authors.initials: N
authors.lastname: Cerrutti
authors.affiliation: INRA, UE1255, UE Entomologie, 17700 Surgères, France.
authors.forename: Pierrick
authors.initials: P
authors.lastname: Aupinel
authors.affiliation: UMT Protection des Abeilles dans l'Environnement, Site Agroparc, 84914 Avignon, France Association de Coordination Technique Agricole, Site Agroparc, 84914 Avignon, France ITSAP-Institut de l'Abeille, Site Agroparc, 84914 Avignon, France.
authors.forename: Axel
authors.initials: A
authors.lastname: Decourtye
authors.affiliation: Terres Inovia, Centre de Grignon, Avenue Lucien Brétignières, 78850 Thiverval Grignon, France.
authors.forename: Mélanie
authors.initials: M
authors.lastname: Gayrard
authors.affiliation: INRA, UE1255, UE Entomologie, 17700 Surgères, France.
authors.forename: Jean-François
authors.initials: JF
authors.lastname: Odoux
authors.affiliation: Association de Coordination Technique Agricole, Site Agroparc, 84914 Avignon, France.
authors.forename: Aurélien
authors.initials: A
authors.lastname: Pissard
authors.affiliation: Terres Inovia, Centre de Grignon, Avenue Lucien Brétignières, 78850 Thiverval Grignon, France.
authors.forename: Charlotte
authors.initials: C
authors.lastname: Rüger
authors.affiliation: Centre d'Etudes Biologiques de Chizé, UMR 7372, CNRS and Université de La Rochelle, 79360 Beauvoir-sur-Niort, France LTER 'Zone Atelier Plaine and Val de Sèvre', Centre d'Etudes Biologiques de Chizé, CNRS, 79360 Villiers-en-Bois, France.
authors.forename: Vincent
authors.initials: V
authors.lastname: Bretagnolle
mesh_terms: D000818:Animals; D001516:Bees / Q000187:drug effects*; D005602:France; D007093:Imidazoles / Q000633:toxicity*; D007306:Insecticides / Q000633:toxicity*; D000073943:Neonicotinoids; D009574:Nitro Compounds / Q000633:toxicity*; D010078:Oxazines / Q000633:toxicity*; D018570:Risk Assessment; D000077922:Thiamethoxam; D013844:Thiazoles / Q000633:toxicity*
chemical_list: D007093:Imidazoles; D007306:Insecticides; D000073943:Neonicotinoids; D009574:Nitro Compounds; D010078:Oxazines; D013844:Thiazoles; C082359:imidacloprid; D000077922:Thiamethoxam
keywords: Apis mellifera; imidacloprid; oilseed rape; pesticides; thiamethoxam