title: Neonicotinoid insecticides can serve as inadvertent insect contraceptives.
abstract: There 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 for managed honeybee queen failure and wild insect pollinator decline. The widespread prophylactic use of neonicotinoids may have previously overlooked inadvertent contraceptive effects on non-target insects, thereby limiting conservation efforts.
authors.affiliation: Institute of Bee Health, Vetsuisse Faculty, University of Bern, Bern, Switzerland lars.straub@vetsuisse.unibe.ch.
authors.forename: Lars
authors.identifier: 0000-0002-2091-1499
authors.initials: L
authors.lastname: Straub
authors.affiliation: Institute of Bee Health, Vetsuisse Faculty, University of Bern, Bern, Switzerland Environmental Science Department, University of Koblenz-Landau, Landau, Germany.
authors.forename: Laura
authors.initials: L
authors.lastname: Villamar-Bouza
authors.affiliation: Institute of Bee Health, Vetsuisse Faculty, University of Bern, Bern, Switzerland.
authors.forename: Selina
authors.initials: S
authors.lastname: Bruckner
authors.affiliation: Bee Protection Laboratory (BeeP), Department of Biology, Faculty of Science, Chiang Mai University, Chiang Mai, Thailand.
authors.forename: Panuwan
authors.initials: P
authors.lastname: Chantawannakul
authors.affiliation: Agroscope, Swiss Bee Research Centre, Bern, Switzerland.
authors.forename: Laurent
authors.initials: L
authors.lastname: Gauthier
authors.affiliation: Bee Protection Laboratory (BeeP), Department of Biology, Faculty of Science, Chiang Mai University, Chiang Mai, Thailand School of Science, Mae Fah Luang University, Chiang Rai, Thailand.
authors.forename: Kitiphong
authors.initials: K
authors.lastname: Khongphinitbunjong
authors.affiliation: Institute of Bee Health, Vetsuisse Faculty, University of Bern, Bern, Switzerland.
authors.forename: Gina
authors.initials: G
authors.lastname: Retschnig
authors.affiliation: Institute of Bee Health, Vetsuisse Faculty, University of Bern, Bern, Switzerland.
authors.forename: Aline
authors.initials: A
authors.lastname: Troxler
authors.affiliation: Veterinary Public Health Institute, Vetsuisse Faculty, University of Bern, Bern, Switzerland.
authors.forename: Beatriz
authors.initials: B
authors.lastname: Vidondo
authors.affiliation: Institute of Bee Health, Vetsuisse Faculty, University of Bern, Bern, Switzerland Bee Protection Laboratory (BeeP), Department of Biology, Faculty of Science, Chiang Mai University, Chiang Mai, Thailand Agroscope, Swiss Bee Research Centre, Bern, Switzerland Department of Zoology and Entomology, University of Pretoria, Pretoria, South Africa.
authors.forename: Peter
authors.initials: P
authors.lastname: Neumann
authors.affiliation: Institute of Bee Health, Vetsuisse Faculty, University of Bern, Bern, Switzerland Bee Protection Laboratory (BeeP), Department of Biology, Faculty of Science, Chiang Mai University, Chiang Mai, Thailand Agroscope, Swiss Bee Research Centre, Bern, Switzerland.
authors.forename: Geoffrey R
authors.initials: GR
authors.lastname: Williams
mesh_terms: D000818:Animals; D001516:Bees / Q000187:drug effects*; D002470:Cell Survival; D003270:Contraceptive Agents / Q000494:pharmacology*; D006146:Guanidines / Q000494:pharmacology*; D007306:Insecticides / Q000494:pharmacology*; D008297:Male; D000073943:Neonicotinoids / Q000494:pharmacology*; D009574:Nitro Compounds; D010078:Oxazines; D012098:Reproduction; D013094:Spermatozoa / Q000166:cytology; D000077922:Thiamethoxam; D013844:Thiazoles / Q000494:pharmacology*
chemical_list: D003270:Contraceptive Agents; D006146:Guanidines; D007306:Insecticides; D000073943:Neonicotinoids; D009574:Nitro Compounds; D010078:Oxazines; D013844:Thiazoles; C480342:clothianidin; D000077922:Thiamethoxam
keywords: Apis mellifera; insecticide; pollination; reproduction; sperm; sub-lethal