title: Size changes in honey bee larvae oenocytes induced by exposure to Paraquat at very low concentrations.
abstract: The effects of the herbicide Paraquat were investigated in honey bee larvae with attention focused on oenocytes. Honey bee larvae were exposed to Paraquat at different concentrations in the food: 0, 0.001, 0.01, 0.1 and 1 µg/kg. In controls, between 24 h and 48 h, oenocytes grew from 630.1 to 1643.8 µm(2) while nuclei changed in size from 124.9 to 245.6 µm(2). At 24 h, Paraquat induced a slight decrease in the size of oenocytes and nuclei. N-acetylcysteine (NAC), an antioxidant substance, slightly lowered the effects of Paraquat. At 48 h, Paraquat elicited a strong concentration-dependent decrease in the size of oenocytes, even at the lowest concentration. NAC reversed the effect of Paraquat at a concentration of ≥0.01 µg/kg. This reversion suggested different modes of action of Paraquat, with an oxidant action prevalent at concentrations ≥0.01 µg/kg. This study is the first which reports an effect of a pesticide at the very low concentration of 1 ng/kg, a concentration below the detection limits of the most efficient analytic methods. It shows that chemicals, including pesticides, are likely to have a potential impact at such exposure levels. We also suggest that Paraquat could be used as a suitable tool for investigating the functions of oenocytes.
authors.affiliation: INRA, UR 406 Abeilles & Environnement, Laboratoire de Toxicologie Environnementale, Avignon, France.
authors.forename: Marianne
authors.initials: M
authors.lastname: Cousin
authors.forename: Elaine
authors.initials: E
authors.lastname: Silva-Zacarin
authors.forename: André
authors.initials: A
authors.lastname: Kretzschmar
authors.forename: Mohamed
authors.initials: M
authors.lastname: El Maataoui
authors.forename: Jean-Luc
authors.initials: JL
authors.lastname: Brunet
authors.forename: Luc P
authors.initials: LP
authors.lastname: Belzunces
mesh_terms: D000818:Animals; D001516:Bees / Q000166:cytology*; D002451:Cell Compartmentation / Q000187:drug effects; D002467:Cell Nucleus / Q000187:drug effects / Q000378:metabolism; D048430:Cell Shape / Q000187:drug effects; D048429:Cell Size; D004781:Environmental Exposure; D006722:Honey; D007814:Larva / Q000166:cytology / Q000187:drug effects; D010269:Paraquat / Q000633:toxicity*
chemical_list: D010269:Paraquat