title: Disruption of quercetin metabolism by fungicide affects energy production in honey bees (Apis mellifera).
abstract: Cytochrome P450 monooxygenases (P450) in the honey bee,Apis mellifera, detoxify phytochemicals in honey and pollen. The flavonol quercetin is found ubiquitously and abundantly in pollen and frequently at lower concentrations in honey. Worker jelly consumed during the first 3 d of larval development typically contains flavonols at very low levels, however. RNA-Seq analysis of gene expression in neonates reared for three days on diets with and without quercetin revealed that, in addition to up-regulating multiple detoxifying P450 genes, quercetin is a negative transcriptional regulator of mitochondrion-related nuclear genes and genes encoding subunits of complexes I, III, IV, and V in the oxidative phosphorylation pathway. Thus, a consequence of inefficient metabolism of this phytochemical may be compromised energy production. Several P450s metabolize quercetin in adult workers. Docking in silico of 121 pesticide contaminants of American hives into the active pocket of CYP9Q1, a broadly substrate-specific P450 with high quercetin-metabolizing activity, identified six triazole fungicides, all fungal P450 inhibitors, that dock in the catalytic site. In adults fed combinations of quercetin and the triazole myclobutanil, the expression of five of six mitochondrion-related nuclear genes was down-regulated. Midgut metabolism assays verified that adult bees consuming quercetin with myclobutanil metabolized less quercetin and produced less thoracic ATP, the energy source for flight muscles. Although fungicides lack acute toxicity, they may influence bee health by interfering with quercetin detoxification, thereby compromising mitochondrial regeneration and ATP production. Thus, agricultural use of triazole fungicides may put bees at risk of being unable to extract sufficient energy from their natural food.
authors.affiliation: Department of Entomology, University of Illinois at Urbana-Champaign, Urbana, IL 61801.
authors.forename: Wenfu
authors.initials: W
authors.lastname: Mao
authors.affiliation: Department of Cell and Developmental Biology, University of Illinois at Urbana-Champaign, Urbana, IL 61801.
authors.forename: Mary A
authors.initials: MA
authors.lastname: Schuler
authors.affiliation: Department of Entomology, University of Illinois at Urbana-Champaign, Urbana, IL 61801; maybe@illinois.edu.
authors.forename: May R
authors.initials: MR
authors.lastname: Berenbaum
mesh_terms: D000255:Adenosine Triphosphate / Q000037:antagonists & inhibitors / Q000096:biosynthesis; D000818:Animals; D001516:Bees / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism; D003577:Cytochrome P-450 Enzyme System / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D045222:Electron Transport Chain Complex Proteins / Q000037:antagonists & inhibitors / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D005659:Fungicides, Industrial / Q000737:chemistry / Q000633:toxicity*; D005786:Gene Expression Regulation; D006722:Honey / Q000032:analysis; D008658:Inactivation, Metabolic / Q000187:drug effects; D019476:Insect Proteins / Q000037:antagonists & inhibitors / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D062105:Molecular Docking Simulation; D009570:Nitriles / Q000737:chemistry / Q000633:toxicity*; D010085:Oxidative Phosphorylation / Q000187:drug effects; D011058:Pollen / Q000737:chemistry / Q000378:metabolism; D011794:Quercetin / Q000037:antagonists & inhibitors* / Q000096:biosynthesis / Q000737:chemistry; D014230:Triazoles / Q000737:chemistry / Q000633:toxicity*
chemical_list: D045222:Electron Transport Chain Complex Proteins; D005659:Fungicides, Industrial; D019476:Insect Proteins; D009570:Nitriles; D014230:Triazoles; D000255:Adenosine Triphosphate; D003577:Cytochrome P-450 Enzyme System; D011794:Quercetin; C446685:systhane
keywords: Apis mellifera; cytochrome P450; flavonol; mitochondria; myclobutanil