Analysis of anticoagulant rodenticides, neonicotinoids and fipronil in liver of predatory birds
Pesticides in predatory birds have been drawing much attention worldwide in regard to species declining and protection. Pesticides are used for pest management of animal species such as commensal rodents and sap-sucking insects. However, pesticides can lead to secondary poisoning, when predators take up pesticide residues from primarily exposed target or non-target species. The analysis focused on anticoagulant rodenticides, neonicotinoids and fipronil which were regularly applied in the years 2011 to 2013. We obtained liver samples of 89 avian predators from this period, which were collected from veterinary institutions or private persons from 26 administrative districts in Germany. Avians were found dead or were euthanized shortly after admission to the veterinarian. Defrosted liver samples were spiked with surrogates and homogenized in a mixture of methanol and water (2:1/v/v) and cleaned up by solid supported liquid extraction with a diatomaceous earth column (Geduhn et al., 2014, DOI 10.1016/j.scitotenv.2014.07.0490048-9697). Quantification of the analytes was performed by LC-ESI-MS/MS with a calibration from 0.1 to 100 ng/ml (r² > 0.99) and a signal to noise ratios > 6:1 for the lowest concentration level. The neonicotinoids imidacloprid with the metabolites 5-OH-IMD and IMD-olefine, thiamethoxam and clothianidin with TZMU and TZNG were not found in the predators although expected especially in case of insectconsuming species such as little owl (Athene noctua). Similarly, we detected no residues of the phenylpyrazole fipronil, which has a higher bioaccumulation potential and the metabolites F-sulfone, F-sulfide and F-carboxamide. One to four substances of the rodenticides chlorophacinone, difenacoum, bromadiolone, brodifacoum, flocoumafen and difethialone were found in 30% of the liver samples, originated from 14 different districts. Brodifacoum was detected in more than 70% of these samples. No sample contained coumatetralyl and warfarin. Residues occurred more often in avian predators specialized on rodents than in generalists; e.g. 44% of the 26 liver samples from common bussards (Buteo buteo) contained residues. The portion was with 80% even higher for red kite (Milvus milvus) but only 5 samples of this species were examined. A residues distribution pattern will be presented but more samples are necessary for final statements.