title: Exposure of honey bees (Apis mellifera) to different classes of insecticides exhibit distinct molecular effect patterns at concentrations that mimic environmental contamination.
abstract: Pesticides are implicated in the decline of honey bee populations. Many insecticides are neurotoxic and act by different modes of actions. Although a link between insecticide exposure and changed behaviour has been made, molecular effects underlying these effects are poorly understood. Here we elucidated molecular effects at environmental realistic concentrations of two organophosphates, chlorpyrifos and malathion, the pyrethroid cypermethrin, and the ryanodine receptor activator, chlorantraniliprole. We assessed transcriptional alterations of selected genes at three exposure times (24 h, 48 h, 72 h) in caged honey bees exposed to different concentrations of these compounds. Our targeted gene expression concept focused on several transcripts, including nicotinic acetylcholine receptor α 1 and α 2 (nAChRα1, nAChRα2) subunits, the multifunctional gene vitellogenin, immune system related genes of three immune system pathways, genes belonging to the detoxification system and ER stress genes. Our data indicate a dynamic pattern of expressional changes at different exposure times. All four insecticides induced strong alterations in the expression of immune system related genes suggesting negative implications for honey bee health, as well as cytochrome P450 enzyme transcripts suggesting an interference with metabolism. Exposure to neurotoxic chlorpyrifos, malathion and cypermethrin resulted in up-regulation of nAChRα1 and nAChRα2. Moreover, alterations in the expression of vitellogenin occurred, which suggests implications on foraging activity. Chlorantraniliprole induced ER stress which may be related to toxicity. The comparison of all transcriptional changes indicated that the expression pattern is rather compound-specific and related to its mode of action, but clusters of common transcriptional changes between different compounds occurred. As transcriptional alterations occurred at environmental concentrations our data provide a molecular basis for observed adverse effects of these insecticides to bees.
authors.affiliation: University of Applied Sciences and Arts Northwestern Switzerland, School of Life Sciences, Gründenstrasse 40, CH-4132 Muttenz, Switzerland.
authors.forename: Verena
authors.initials: V
authors.lastname: Christen
authors.affiliation: University of Applied Sciences and Arts Northwestern Switzerland, School of Life Sciences, Gründenstrasse 40, CH-4132 Muttenz, Switzerland; Swiss Federal Institute of Technology Zürich (ETH Zürich), Department of Environmental System Sciences, Institute of Biogeochemistry and Pollution Dynamics, CH-8092 Zürich, Switzerland. Electronic address: karl.fent@fhnw.ch.
authors.forename: Karl
authors.initials: K
authors.lastname: Fent
mesh_terms: D000818:Animals; D001516:Bees / Q000187:drug effects* / Q000502:physiology; D004390:Chlorpyrifos / Q000633:toxicity; D003577:Cytochrome P-450 Enzyme System / Q000378:metabolism; D004785:Environmental Pollutants / Q000633:toxicity*; D015870:Gene Expression; D008658:Inactivation, Metabolic; D007306:Insecticides / Q000633:toxicity*; D008294:Malathion / Q000633:toxicity; D010575:Pesticides; D011722:Pyrethrins / Q000633:toxicity; D015854:Up-Regulation
chemical_list: D004785:Environmental Pollutants; D007306:Insecticides; D010575:Pesticides; D011722:Pyrethrins; C017160:cypermethrin; D003577:Cytochrome P-450 Enzyme System; D004390:Chlorpyrifos; D008294:Malathion
keywords: Gene expression; Honey bees; Organophosphates; Pesticide exposure; Pyrethroids