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.

Landscape and pesticide effects on honey bees: forager survival and expression of acetylcholinesterase and brain oxidative genes

“…The equivocal results obtained from studies on honey bee in-field pesticide toxicity and exposure, tolerated level of exposure, and effect on honey bee health (Blacquière et al 2012;Henry et al 2015) have raised new questions and debates. It is believed that in order to ameliorate these problems and find sustainable solutions, closer collaborations and information exchange between pesticides companies, the scientific community, agriculturists, and beekeepers is strongly needed.…”

Pesticide Use in Northern Ireland’s Arable Crops from 1992–2016 and Implications for Future Policy Development

“…In addition, seed treatments may pose a serious risk to non-target birds and mammals [10][11][12]. Moreover, the potential side-effects of the introduction of seed treatments with neonicotinoid active substances on vertebrates and invertebrates, particularly bees, are contentious [13][14][15][16][17][18] The rapid increase in the use of neonicotinoid seed treatments in Northern Ireland arable crops, particularly on winter wheat, following their introduction in 2006, was similar to that recorded by Douglas and Tooker [19] in the United States where these seed treatments were driving increased pre-emptive pest management in that region. In 2013, the EU severely restricted the use of plant protection products and treated seeds containing three of these neonicotinoids (clothianidin, imidacloprid and thiamethoxam) to protect honeybees.…”

De la concertation territoriale à l'expérimentation en plein champs, différents leviers pour accompagner les acteurs d'un territoire agricole à façonner des paysages durablement favorables à des productions oléagineuses et des productions de miel

“…Cependant ces pollen peuvent potentiellement être contaminés par des substances d'origine agricoles comme l'imidaclopride (molécule insecticide systémique employée en enrobage de semences de céréales, rémanente dans le sol, fortement toxique pour les abeilles) . L'implantation d'espèces potentiellement attractives pour des insectes pollinisateurs, doit intégrer une réflexion sur les risques potentiels de contamination de cette ressource : intervention sur ou à proximité de cette ressource, rémanence de molécules dans les sols pouvant être remobilisés par cette ressource (Botias et al, 2015 ;Henry et al, 2015). références similaires avaient été données sur ce même territoire en 2013 (Rollin et al, 2013).…”