Straub, LarsVillamar-Bouza, LauraBruckner, SelinaChantawannakul, PanuwanGauthier, LaurentKhongphinitbunjong, KitiphongRetschnig, GinaTroxler, AlineVidondo, BeatrizNeumann, PeterWilliams, Geoffrey R.2016-09-272016-09-272016-05-06Straub, L., Villamar-Bouza, L., Bruckner, S., Chantawannakul, P., Gauthier, L., Khongphinitbunjong, K., Retschnig, G., Troxler, A., Vidondo, B., Neumann, P. & Williams, G.R. 2016 Neonicotinoid insecticides can serve as inadvertent insect contraceptives. Proceedings of the Royal Society B: Biological Sciences 283: 20160506, pp. 1-7.0962-8452 (print)1471-2954 (online)10.1098/rspb.2016.050610.5061/dryad.bs515http://hdl.handle.net/2263/57026There is clear evidence for sublethal effects of neonicotinoid insecticides on non-target ecosystem service-providing insects. However, their possible impact on male insect reproduction is currently unknown, despite the key role of sex. Here, we show that two neonicotinoids (4.5 ppb thiamethoxam and 1.5 ppb clothianidin) significantly reduce the reproductive capacity of male honeybees (drones), Apis mellifera. Drones were obtained from colonies exposed to the neonicotinoid insecticides or controls, and subsequently maintained in laboratory cages until they reached sexual maturity. While no significant effects were observed for male teneral (newly emerged adult) body mass and sperm quantity, the data clearly showed reduced drone lifespan, as well as reduced sperm viability (percentage living versus dead) and living sperm quantity by 39%. Our results demonstrate for the first time that neonicotinoid insecticides can negatively affect male insect reproductive capacity, and provide a possible mechanistic explanation formanaged honeybee queen failure andwild insect pollinator decline. Thewidespread prophylactic use of neonicotinoids may have previously overlooked inadvertent contraceptive effects on non-target insects, thereby limiting conservation efforts.en© 2016 The Authors. Published by the Royal Society under the terms of the Creative Commons Attribution License.Apis melliferaInsecticidePollinationReproductionSpermSub-lethalArticle