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. Five bee colonies were treated with regular dose of CheckMite (Bayer), in five 1.5x therapeutic dose was used, while five colonies served as controls. Honey and brood samples were collected before, during and at the end of 6-week treatment. Determination of coumaphos in honey and bee brood was based on RP-HPLC with UV detection after a liquid – liquid extraction with hexane. The results have shown that coumaphos levels in honey was not reached MRL (100 μg/kg), however level above MRL was found in one beehive. In bee brood from regular and exceed treated beehives the presence of coumaphos (up to 909 μg/kg) was found during and at the end of the treatment. Results have shown that coumaphos accumulates in bee brood.
Lasalocid is an ionophore antibiotic used for prevention and treatment of coccidiosis in poultry. It is excreted from the treated animals mostly in its active form and enters the environment with the use of contaminated manure on agricultural land. A research was undertaken to ascertain the rate of lasalocid degradation in manure under different storage conditions (aging in a pile or composting) and on agricultural soil after using lasalocid-contaminated manure. The results have shown difference in lasalocid degradation between aging manure with no treatment (t1/2 = 61.8 ± 1.7 d) and composting (t1/2 = 17.5 ± 0.8 d). Half-lives in soil are much shorter (on average 3.1 ± 0.4 d). On the basis of the measured concentrations of lasalocid in soil after manure application, we can conclude that it can potentially be harmful to soil oraganisms. To make certain that no harmful effects occur, composting is recommended.