Distribution of [(14)C]imidacloprid in sunflowers (Helianthus annuus L.) following seed treatment.
Imidacloprid, a neonicotinic insecticide, has been used as a seed dressing (Gaucho) to protect crops against soil and aerial insects. However, French beekeepers observed abnormal behavior of bees foraging on sunflowers and suspected a link between the imidacloprid seed treatment and the observed bee syndrome. This work studies the distribution of [(14)C-imidazolidin]imidacloprid (1 mg/seed) in three stages of Gaucho-treated sunflowers grown in an outdoor lysimeter. Plants absorbed <10% of [(14)C]imidacloprid spiked on seeds, and 75% of that absorbed radioactivity was found in cotyledons. Concentrations in the upper leaves were 20 times lower than in the first leaves. From the extracted radioactivity, imidacloprid accounted for 50% and metabolites for the other 50%. Four major metabolites can be detected, in variable concentrations, among which the hydroxy- and olefin-imidacloprid have toxicities equivalent to that of imidacloprid. In pollen, concentrations of imidacloprid were 13 ng x g(-1). Thus, imidacloprid residues from Gaucho seed treatment contaminated sunflower pollen, involving the translocation of imidacloprid within the plant.
Laurent
François M
FM
INRA, UMR Xénobiotiques, B.P. 3, 180 chemin de Tournefeuille, 31931 Toulouse Cedex 9, France. flaurent@toulouse.inra.fr
Rathahao
Estelle
E
D000818:Animals; D001516:Bees / Q000187:drug effects; D002250:Carbon Radioisotopes; D006368:Helianthus / Q000737:chemistry*; D007093:Imidazoles / Q000008:administration & dosage* / Q000032:analysis* / Q000378:metabolism; D000073943:Neonicotinoids; D009574:Nitro Compounds; D010573:Pesticide Residues / Q000032:analysis*; D018515:Plant Leaves / Q000378:metabolism; D018517:Plant Roots / Q000378:metabolism; D011058:Pollen / Q000737:chemistry; D012639:Seeds / Q000737:chemistry* / Q000378:metabolism
D002250:Carbon Radioisotopes; D007093:Imidazoles; D000073943:Neonicotinoids; D009574:Nitro Compounds; D010573:Pesticide Residues; C082359:imidacloprid