A two-year monitoring of pesticide hazard in-hive: High honey bee mortality rates during insecticide poisoning episodes in apiaries located near agricultural settings.

Pesticide residues in beebread, live and dead honey bees, together with honey bee death rate were monitored from June 2016 to June 2018 in three apiaries, located near agricultural settings and in wildlands. Dead honey bees were only collected and analyzed when significant mortality episodes occurred and pesticide content in beeswax of each experimental apiary was evaluated at the beginning of the study. Samples were extracted by a modified QuEChERS procedure and screened for pesticides residues by liquid chromatography mass spectrometry (LC-MS/MS). Pesticide hazard in the samples was evaluated through the hazard quotient approach (HQ). Beebread was widely contaminated with coumaphos and amitraz degradate 2, 4-dimethylphenylformamide (DMF), miticides detected in 94 and 97% of samples respectively. However, insecticides sprayed during citrus bloom like chlorpyrifos (up to 167 ng g -1) and dimethoate (up to 34 ng g -1) were the main responsible of the relevant pesticide hazard in this matrix. Pesticide levels in live bees were mostly residual, and pesticide hazard was low. Beeswax of the apiaries, contaminated by miticides, revealed a low pesticide hazard to honey bee colonies. Acute mortality episodes occurred only in the two apiaries located near agricultural settings. Dead bees collected during these episodes revealed high levels (up to 2700 ng g -1) of chlorpyrifos, dimethoate, omethoate and imidacloprid. HQ calculated in dead bees exceeded up to 37 times the threshold value considered as elevated hazard to honey bee health.

Pesticide occurrence in the waters of Júcar River, Spain from different farming landscapes.

A combined methodology to identify and quantify farming chemicals in the entire Júcar River basin has been developed. The procedure consisted of the application of environmental forensic criteria associating laboratory analytical samples, cartographic analysis using Geographical Information Systems (GIS) and synthetic statistical analysis. Sampling involved the collection of 15 samples in surface waters distributed alongside the Júcar River and its two main tributaries (Cabriel and Magro Rivers). The analytical procedure involves generic sample extraction and selective determination of up to 50 target pesticides by liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS). Geographical analysis was performed by mixing both sampling points with analytical results and land use-cover layers for the year 2011. PCA and descriptive statistical analysis was further performed combining land use/cover information and pesticides results to determine correlation between dominant agricultural practices (irrigation and rain fed farming) and location of sampling points. Out of 50 pesticides, 20 were identified and 18 presented concentrations higher than the limits of quantification in surface waters, with a large dispersion in concentrations: from 0.05ng/L (terbuthylazine-2 hydroxy) to 222.45ng/L (imazalil). Statistical analyses reveals that there is a correlation between the percentage of land devoted to irrigation farming, whereas correlations are weaker when analysing the relationship of pesticides in rain fed dominated areas.