title: Sublethal pesticide doses negatively affect survival and the cellular responses in American foulbrood-infected honeybee larvae.
abstract: Disclosing interactions between pesticides and bee infections is of most interest to understand challenges that pollinators are facing and to which extent bee health is compromised. Here, we address the individual and combined effect that three different pesticides (dimethoate, clothianidin and fluvalinate) and an American foulbrood (AFB) infection have on mortality and the cellular immune response of honeybee larvae. We demonstrate for the first time a synergistic interaction when larvae are exposed to sublethal doses of dimethoate or clothianidin in combination with Paenibacillus larvae, the causative agent of AFB. A significantly higher mortality than the expected sum of the effects of each individual stressor was observed in co-exposed larvae, which was in parallel with a drastic reduction of the total and differential hemocyte counts. Our results underline that characterizing the cellular response of larvae to individual and combined stressors allows unmasking previously undetected sublethal effects of pesticides in colony health.
authors.affiliation: Institute of Zoology, Universitätsplatz 2, University of Graz, A-8010 Graz, Austria.
authors.forename: Javier Hernández
authors.initials: JH
authors.lastname: López
authors.affiliation: Institute of Zoology, Universitätsplatz 2, University of Graz, A-8010 Graz, Austria.
authors.forename: Sophie
authors.initials: S
authors.lastname: Krainer
authors.affiliation: Institute of Zoology, Universitätsplatz 2, University of Graz, A-8010 Graz, Austria.
authors.forename: Antonia
authors.initials: A
authors.lastname: Engert
authors.affiliation: Institute of Zoology, Universitätsplatz 2, University of Graz, A-8010 Graz, Austria.
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Schuehly
authors.affiliation: Institute of Zoology, Universitätsplatz 2, University of Graz, A-8010 Graz, Austria.
authors.forename: Ulrike
authors.initials: U
authors.lastname: Riessberger-Gallé
authors.affiliation: Institute of Zoology, Universitätsplatz 2, University of Graz, A-8010 Graz, Austria.
authors.forename: Karl
authors.initials: K
authors.lastname: Crailsheim
mesh_terms: D000818:Animals; D001516:Bees / Q000187:drug effects* / Q000382:microbiology; D002470:Cell Survival; D004117:Dimethoate / Q000633:toxicity*; D006146:Guanidines / Q000633:toxicity*; D007814:Larva / Q000187:drug effects / Q000382:microbiology; D007928:Lethal Dose 50; D000073943:Neonicotinoids / Q000633:toxicity*; D009570:Nitriles / Q000633:toxicity*; D000070059:Paenibacillus larvae / Q000472:pathogenicity; D010575:Pesticides / Q000633:toxicity*; D011722:Pyrethrins / Q000633:toxicity*; D013844:Thiazoles / Q000633:toxicity*
chemical_list: D006146:Guanidines; D000073943:Neonicotinoids; D009570:Nitriles; D010575:Pesticides; D011722:Pyrethrins; D013844:Thiazoles; C480342:clothianidin; C034227:fluvalinate; D004117:Dimethoate