title: Uptake of Neonicotinoid Insecticides by Water-Foraging Honey Bees (Hymenoptera: Apidae) Through Guttation Fluid of Winter Oilseed Rape.
abstract: The water-foraging activity of honey bees (Apis mellifera L.) on guttation fluid of seed-coated crops, such as winter oilseed rape (WOR; Brassica napus L.), has not yet been evaluated. We analyzed the uptake of active substances (a.s.) in guttation fluid by evaluating residues of honey-sac contents. In autumn, insecticide residues of up to 130 µg a.s. per liter were released in WOR guttation fluid; this concentration is noticeably lower than levels reported in guttation fluid of seed-coated maize. Until winter dormancy, the concentrations declined to <30 µg a.s. per liter. In spring, residues were linked to prewintered plants and declined steadily until flowering. The maximum release of residues in guttation fluid of seed-coated WOR occurs on the first leaves in autumn when the colonies' water demand decreases. For the first time, proof for the uptake of guttation fluid from seed-coated WOR by honey bees was provided by measuring residues in individual honey-sac contents. In total, 38 out of 204 samples (19%) showed residues of thiamethoxam at concentrations ranging from 0.3 to 0.95 µg per liter while the corresponding concentrations in guttation fluid of WOR varied between 3.6 to 12.9 µg thiamethoxam per liter. The amounts of thiamethoxam we found in the honey sacs of water-foraging honey bees were therefore below the thresholds in nectar and pollen that are considered to have negative effects on honey bees after chronic exposure.
authors.affiliation: Apicultural State Institute, University of Hohenheim, August-von-Hartmann-Str. 13, D-70593 Stuttgart, Germany (reetz@uni-hohenheim.de; Klaus.Wallner@uni-hohenheim.de), reetz@uni-hohenheim.de.
authors.forename: J E
authors.initials: JE
authors.lastname: Reetz
authors.affiliation: Zweckverband Landeswasserversorgung, Laboratory for Operation Control and Research, Am Spitzigen Berg 1, D-89129 Langenau, Germany (Schulz.W@lw-online.de; Seitz.W@lw-online.de).
authors.forename: W
authors.initials: W
authors.lastname: Schulz
authors.affiliation: Zweckverband Landeswasserversorgung, Laboratory for Operation Control and Research, Am Spitzigen Berg 1, D-89129 Langenau, Germany (Schulz.W@lw-online.de; Seitz.W@lw-online.de).
authors.forename: W
authors.initials: W
authors.lastname: Seitz
authors.affiliation: Institute of Environmental Research (INFU), Faculty of Chemistry and Chemical Biology, Technical University Dortmund, Otto-Hahn-Str. 6, D-44227 Dortmund, Germany (m.spiteller@infu.uni-dortmund.de; S.Zuehlke@infu.uni-dortmund.de), and.
authors.forename: M
authors.initials: M
authors.lastname: Spiteller
authors.affiliation: Institute of Environmental Research (INFU), Faculty of Chemistry and Chemical Biology, Technical University Dortmund, Otto-Hahn-Str. 6, D-44227 Dortmund, Germany (m.spiteller@infu.uni-dortmund.de; S.Zuehlke@infu.uni-dortmund.de), and.
authors.forename: S
authors.initials: S
authors.lastname: Zühlke
authors.affiliation: Institute of Food Chemistry and Analytical Chemistry, University of Hohenheim, Garbenstr. 28, D-70593 Stuttgart, Germany (wolfgang.armbruster@uni-hohenheim.de).
authors.forename: W
authors.initials: W
authors.lastname: Armbruster
authors.affiliation: Apicultural State Institute, University of Hohenheim, August-von-Hartmann-Str. 13, D-70593 Stuttgart, Germany (reetz@uni-hohenheim.de; Klaus.Wallner@uni-hohenheim.de).
authors.forename: K
authors.initials: K
authors.lastname: Wallner
mesh_terms: D000818:Animals; D001516:Bees / Q000502:physiology*; D029688:Brassica napus / Q000378:metabolism*; D002851:Chromatography, High Pressure Liquid; D005247:Feeding Behavior; D005858:Germany; D006146:Guanidines / Q000378:metabolism; D007093:Imidazoles / Q000378:metabolism; D007306:Insecticides / Q000378:metabolism*; D013058:Mass Spectrometry; D000073943:Neonicotinoids; D009574:Nitro Compounds / Q000378:metabolism; D010078:Oxazines / Q000378:metabolism; D010573:Pesticide Residues / Q000032:analysis; D018515:Plant Leaves / Q000378:metabolism; D057048:Plant Nectar / Q000737:chemistry; D011058:Pollen / Q000737:chemistry; D012621:Seasons; D000077922:Thiamethoxam; D013844:Thiazoles / Q000378:metabolism; D014867:Water / Q000378:metabolism*
chemical_list: D006146:Guanidines; D007093:Imidazoles; D007306:Insecticides; D000073943:Neonicotinoids; D009574:Nitro Compounds; D010078:Oxazines; D010573:Pesticide Residues; D057048:Plant Nectar; D013844:Thiazoles; D014867:Water; C480342:clothianidin; C082359:imidacloprid; D000077922:Thiamethoxam
keywords: guttation; honey sac; neonicotinoid; seed coating; winter oilseed rape