We presented our preliminary results on the degradation of lasalocid under different manure storage conditions (in a pile and as compost). There were marked differences between the two treatments. Lasalocid in manure degraded with a half-life of 61.8 days and did not fall below 45% of the initial concentrations even after 84 days, whereas its half-life in compost was 17.5 days and the concentrations fell below the limit of detection (10 ng/g) after 80 days. Broiler manure is usually aged for approximately three months before application on land. In most cases on Slovenian farms, it is simply left in a pile with no additional treatment such as aeration, moistening or mixing with plant material. We can therefore expect that about one half of the initial lasalocid levels reach the environment. At initial concentrations of about 10 mg/kg, which can be expected in broiler excreta and which were measured for monensin, which is structurally similar to lasalocid, the PEC for lasalocid in soil after three months of aging would be 0.031 mg/kg. The lowest EC50 value reported for soil organisms was 4.9 mg/kg soil for isopod avoidance. Using an assessment factor of 100, the PNEC would be lower than PEC and the risk quotient for lasalocid in agricultural soil would be below 1 (0.63). We can therefore conclude on the basis of our preliminary results that the current practice of manure storage is sufficient to pose no risk to soil organisms. However, continual use of lasalocid-contaminated manure on the same area could increase the risk and composting would be recommended.
B.06 OtherCOBISS.SI-ID: 3692410
The aim of the study was to assess the accumulation of coumaphos and amitraz residua in honey, bee brood and beeswax after the treatment of honeybee colonies against varosis (Varroa destrucor). The study was conducted in two apiaries on two different locations. In the first location ten bee colonies of Apis melifica carnica were treated with coumaphos (CheckMite, Bayer, Germany) and on other location five bee colonies were treated with amitraz (Apivar, Veto-Pharma, France). Non-treated colonies served as controls. Honey, wax and brood samples were collected before and six weeks after the treatment. Detection of coumaphos and amitraz and its metabolites DPMF, DMF and DMA in honey and brood was performed by HPLC with UV detection, while wax coumaphos and amitraz and its metabolites were determined using GC. Coumaphos levels in honey from treated and non-treated bee colonies were found bellow MRL (100 μg/kg). In the brood from treated colonies coumaphos levels ranged between 49.0 and 784.1 μg/kg. Interestingly, coumaphos in wax was found in treated and non-treated bee colonies. The levels of coumaphos in the wax were high and ranged between 0.19 and 36 mg/kg. High coumaphos residua accumulation in wax in both treated and untreated colonies are probably the results of the bee colonies treatments with coumaphos before the reasearch. However, the levels of amitraz and its metabolites were found bellow limit of detection.
B.06 OtherCOBISS.SI-ID: 3794042