TY - JOUR A1 - Wessler, Ignaz A1 - Gärtner, Hedwig-Annabel A1 - Michel-Schmidt, Rosmarie A1 - Brochhausen, Christoph A1 - Schmitz, Luise A1 - Anspach, Laura A1 - Grünewald, Bernd A1 - Kirkpatrick, Charles James T1 - Honeybees produce millimolar concentrations of non-neuronal acetylcholine for breeding: possible adverse effects of neonicotinoids T2 - PLoS one N2 - The worldwide use of neonicotinoid pesticides has caused concern on account of their involvement in the decline of bee populations, which are key pollinators in most ecosystems. Here we describe a role of non-neuronal acetylcholine (ACh) for breeding of Apis mellifera carnica and a so far unknown effect of neonicotinoids on non-target insects. Royal jelly or larval food are produced by the hypopharyngeal gland of nursing bees and contain unusually high ACh concentrations (4–8 mM). ACh is extremely well conserved in royal jelly or brood food because of the acidic pH of 4.0. This condition protects ACh from degradation thus ensuring delivery of intact ACh to larvae. Raising the pH to ≥5.5 and applying cholinesterase reduced the content of ACh substantially (by 75–90%) in larval food. When this manipulated brood was tested in artificial larval breeding experiments, the survival rate was higher with food supplemented by 100% with ACh (6 mM) than with food not supplemented with ACh. ACh release from the hypopharyngeal gland and its content in brood food declined by 80%, when honeybee colonies were exposed for 4 weeks to high concentrations of the neonicotinoids clothianidin (100 parts per billion [ppb]) or thiacloprid (8,800 ppb). Under these conditions the secretory cells of the gland were markedly damaged and brood development was severely compromised. Even field-relevant low concentrations of thiacloprid (200 ppb) or clothianidin (1 and 10 ppb) reduced ACh level in the brood food and showed initial adverse effects on brood development. Our findings indicate a hitherto unknown target of neonicotinoids to induce adverse effects on non-neuronal ACh which should be considered when re-assessing the environmental risks of these compounds. To our knowledge this is a new biological mechanism, and we suggest that, in addition to their well documented neurotoxic effects, neonicotinoids may contribute to honeybee colony losses consecutive to a reduction of the ACh content in the brood food. Y1 - 2016 UR - http://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/41504 UR - https://nbn-resolving.org/urn:nbn:de:hebis:30:3-415040 UR - https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4902251/ SN - 1932-6203 N1 - Copyright: © 2016 Wessler et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. VL - 11 IS - (6): e0156886 SP - 1 EP - 18 PB - PLoS CY - Lawrence, Kan. ER -