Agricultural pesticides and veterinary substances in Uruguayan beeswax.

Over the last decade, Uruguay has expanded and intensified its rainfed crop production. This process has affected beekeeping in several ways: for example, by reducing the space available. This has increased the density of apiaries, the risk of varroosis and acaricide use. Additionally, the dominance of no-tillage crops has increased the frequencies of application and of loads of pesticides in regions where such crops share the land with beekeeping and honey production. Therefore, the exposure of bees to xenobiotics (agricultural pesticides and veterinary products) has increased in line with pollution of hives and their products. To document pollution from hive exposure to pesticides, we surveyed the presence of 30 xenobiotics normally used in Uruguay, in recycled beeswax (RB) and in honey cappings (HC) from the main Uruguayan beekeeping regions. There was contamination of all the analyzed samples (RB and HC) with the herbicide atrazine at a range of 1-2 ng g-1. At least three or four additional xenobiotics were detected: insecticides (chlorpyrifos-ethyl and thiacloprid); fungicides (azoxystrobin and tebuconazole); and veterinary products (coumaphos, ethion, and tau-fluvalinate). The frequency of detection of chlorpyrifos-ethyl and coumaphos in RB samples was higher than in those of HC. Moreover, the concentrations of azoxystrobin, coumaphos, and tebuconazole in RB samples were higher than in HC samples. Therefore, we suggest the use of HC to produce recycled printed beeswax films for use in hives to minimize pollution transfer.

Acute contact toxicity test of insecticides (Cipermetrina 25, Lorsban 48E, Thionex 35) on honeybees in the southwestern zone of Uruguay.

Glyphosate-resistant soybean cultivation is expanding rapidly in Uruguay, with its land area having increased by 95 times during the past 10 years. Because of the region's Neotropical conditions, insecticide use is required to ensure adequate soybean productivity. However, in areas shared by soybean crops and beekeepers - such as the southwestern zone of Uruguay (SWZU) - the use of insecticides can increase the risks of honeybee death and honey contamination. Uruguayan commercial and legal guidelines set out practices and field doses designed to prevent acute intoxication with insecticides. However, honeybees in the SWZU are predominantly a polyhybrid subspecies different from that used to set international reference values, and hence they may have a different acute toxicity response, thus rendering such precautions ineffective. The aim of this work was to assess the acute toxicity response of polyhybrid honeybees in the SWZU to cypermethrin (commercial formulation: Cipermetrina 25 Agrin®), chlorpyrifos (commercial formulation: Lorsban 48E®), and endosulfan (commercial formulation: Thionex 35®). Acute toxicity bioassays were conducted to determine the median lethal dose (LD(50)) of each insecticide for the honeybees. The results indicate that, compared with EU reference values, SWZU honeybees have a higher toxicological sensitivity to chlorpyrifos and endosulfan, and a lower toxicological sensitivity to cypermethrin, based on the commercial formulations tested. However, when these results were adjusted according to their field dose equivalents, only chlorpyrifos emerged as a potential problem for beekeeping, as the maximum recommended field dose of Lorsban 48E® for soybean crops in Uruguay is 23 times the corresponding LD(50) for honeybees in the SWZU.