Evaluation of the presence of the pesticides sulfoxaflor and chlorpyrifos added to the wax of africanized Apis mellifera honey bees

Abstract

Among all beekeeping products, beeswax has the lowest replacement rate and, under natural conditions, combs can remain in the hive for many years. However, in commercial beekeeping management, combs are processed by beekeepers to extract wax for sale; this continuous cycle can lead to the accumulation of various pesticide residues. Among these, sulfoxaflor (an insecticide from the sulfoximine chemical group) and chlorpyrifos (a widely used organophosphate for the control of insects and mites) have harmful effects on bees and may consequently impair their productivity. Therefore, the objective of this study was to contaminate beeswax with sulfoxaflor and chlorpyrifos and assess their presence using high-performance liquid chromatography (Shimadzu). For this purpose, raw beeswax was obtained from a commercial producer in a single batch. Then, 40 grams were melted at approximately 70°C in a water bath, and the pesticides were added: sulfoxaflor at a concentration of 16.97 µg/kg and chlorpyrifos at 24.95 µg/kg. After this process, 1 gram of the contaminated wax was weighed and mixed with 100 mL of methanol, kept in a water bath at 80°C for 25 minutes. Next, the solution was placed in liquid nitrogen and ground until the wax turned into powder. Then, 0.5 grams of the powdered solution were separated and 50 mL of methanol were added; the mixture was kept in an ultrasonic bath at 80°C for approximately 20 minutes. Afterward, the solution was centrifuged for 5 minutes at 4,000 rpm in a refrigerated centrifuge at 20°C. After chromatographic analysis, it was observed that the added pesticides were recovered at the expected concentrations. This result reinforces the idea that beeswax can act as a reservoir for pesticides in the hive, potentially affecting the colony and its productivity in a chronic way, thus harming the beekeeping industry.