Monensin and lasalocid are polyether ionophore antibiotics used in veterinary medicine for prevention and treatment of coccidiosis in poultry. They are extensively used in the poultry industry throughout Europe. Both substances are excreted with the faeces mostly in their active form. The use of manure from treated animals on agricultural soil results in contamination that could pose a threat to soil organisms and thereby reduce the production potential of farmlands. Their degradation rates in manure and soil, as well as their effects on non-target soil organisms are mostly unknown. We conducted several studies to measure the degradation of lasalocid and monensin in broiler manure and after application to soil. Ecotoxicological studies were also performed to obtain concentrations at which these coccidiostats are harmful to soil invertebrates, namely earthworms and woodlice. Degradation rates in manure and compost depend mostly on moisture levels and temperature. Half-lives in compost are significantly shorter than if manure is aged in a pile with no treatment. Avoidance of the test animals was the most sensitive endpoint in the ecotoxicity tests. On the basis of our results, we recommend that poultry manure from treated animals be stored for at least one month before application to soil.
The aim of the study was to assess the presence of coumaphos residues in honey and bee brood after the treatment of honeybee colonies against varosis (Varroa destrucor). The study was conducted in two apiaries on two geographically different parts of Slovenia. Five colonies from each location were treated with therapeutic or 1.5X therapeutic dose of coumaphos (CheckMite, Bayer), five non-treated colonies from each location served as controls. Honey and bee brood samples were collected before and on the 6th week of the treatment, brood samples were collected additionally in the middle of the treatment. Determination of coumaphos residues in honey and bee brood was based on RP-HPLC with UV detection after a liquid – liquid extraction with hexane. Coumaphos levels in honey samples before treatment of bee colonies were found bellow MRL (100 μg/kg). After the treatment only one sample from a bee colony at first location, where therapeutic dose was used, contained 238.8 μg/kg of coumaphos. Values of coumaphos in all other honey samples were below limit of quantification (LOQ). Similarly, levels of coumaphos in all bee brood samples before treatment were below LOQ. The levels of coumaphos in brood taken at the end of treatment with therapeutic dose ranged between 86.9 and 428.7 μg/kg on the first location and between 143.5 and 567.8 μg/kg on the second location. In the brood samples, taken at the end of treatment with 1.5 therapeutic dose, from 88.7 to 909.0 μg coumaphos per kg was found. To conclude, the results from our study indicate the accumulation of coumaphos in bee brood.