Pesticide residues in beeswax and beebread samples collected from honey bee colonies (Apis mellifera L.) in Spain. Possible implications for bee losses

Abstract

SummaryTwo experiments were carried out on professional bee hives in Spain in order to measure the levels of contamination in beeswax and beebread and its possible relation to the bee losses currently found in bees. In beeswax the main components that we found were chlorfenvinphos and tau-fluvalinate. Chlorfenvinphos was detected in 100% of the samples analyzed (n=32) with an average concentration of 449.28 μg kg−1 ± 708.42 μg kg−1 (range: 20.45 μg kg−1–3182.31 μg kg−1). Tau-fluvalinate was detected in 96.8% of the samples analyzed (n=32) with an average concentration of 996.49 μg kg−1 ± 2384.37 μg kg−1 (range: <LD μg kg−1–12978.73 μg kg−1). In beebread the most frequent acaricide was chlorfenvinphos, being detected in 90.6% of the samples analyzed (n= 32) with an average concentration of 35.9 μg kg−1 ± 60.86 μg kg−1 (range: <LD μg kg−1–285.56 μg kg−1). The samples from depopulated apiaries showed higher concentrations of this compound as compared to the non-depopulated apiaries (74.62 μg kg−1 vs. 23.84 μg kg−1; F = 4.254; p = 0.048). This tendency was found in the studies of the accumulated acaricides in beeswax coming from hives with both a high or low survival rate. Of the beebread samples taken 59.4% had detectable levels of other agricultural pesticides and in total 16 active ingredients were detected. If we consider acaricides and agricultural pesticides together, 100% of the samples had some kind of contamination. The possible impact of acaricides and agricultural pesticides and cocktails of these in beebread fed to bee larvae is discussed.