Quantitation of pesticides in bee bread collected from honey bee colonies in an agricultural environment in Switzerland

Abstract

Pesticide contamination of bee products is a widespread phenomenon. Due to its composition, bee bread is affected by both lipophilic and hydrophilic substances. As proof of concept of a monitoring campaign and to better understand the extent of contamination, we developed an analytical method based on a modified QuEChERS extraction, with subsequent separation by liquid chromatography and detection by mass spectrometry. This allowed for the quantitation of 51 agricultural- or beekeeping-associated pesticides in bee bread. The workflow was applied to 60 samples taken biweekly throughout spring to autumn 2022 from five colonies at a Swiss apiary in an agricultural area. In total, 30 pesticides were identified (> LOD), among which 26 pesticides were quantitated. The total number of pesticides detected per colony ranged from 11 to 19. The most prevalent substances (> LOQ) were two neonicotinoid insecticides, acetamiprid and thiacloprid (max. 16 μg/kg and 37 μg/kg, respectively); seven fungicides, azoxystrobin (max. 72 μg/kg), boscalid (max. 50 μg/kg), cyprodinil (max. 1965 μg/kg), difenoconazole (max. 73 μg/kg), mandipropamid (max. 33 μg/kg), pyraclostrobin (max. 8 μg/kg) and trifloxystrobin (max. 38 μg/kg); and two herbicides, prosulfocarb (max. 38 μg/kg) and terbuthylazine (max. 26 μg/kg). The study revealed strong variability in pesticide occurrence and concentrations among colonies sampled at the same site and date. The applied biweekly sampling of bee bread from March to August was shown to be reliable in capturing peak contaminations and revealing the onset of certain pesticides in bee bread. The study provides an adequate practical approach for pesticide monitoring campaigns.

Considering pollinators' ecosystem services in the remediation and restoration of contaminated lands: Overview of research and its gaps

“…Most studies of chemical contaminant effects on pollinators involved agricultural chemicals (mainly pesticides, fungicides, and herbicides) or pesticides used for honeybee colony hygiene (Schaad et al, 2023). Studies with industrial chemicals (e.g., polychlorinated biphenyls, polycyclic aromatic hydrocarbons, volatile organic compounds) were not Iovanna et al (2017).…”

“…Overall, the three bee species did not show extreme variance in their responses to the chemicals despite differences in life histories. Schaad et al (2023) found 26 pesticides, seven fungicides, and two herbicides in bee bread from honeybee colonies in an agricultural matrix in Switzerland. These studies involved oral exposure; no studies were found on cuticular and/or epithelial exposure, for example, in ground‐nesting bees whose larvae reside in contact with soil or with cell membranes excreted by the mother: this remains an unknown exposure pathway.…”

Bee Bread: A Promising Source of Bioactive Compounds with Antioxidant Properties—First Report on Some Antimicrobial Features

“…Other findings reported BB as a powerful biomarker/biomonitor, according to Schaad et al [ 38 ], who quantified pesticides in BB samples collected from honeybees in an agricultural environment in Switzerland. The study results provided a significant basis for monitoring pesticide contamination [ 39 ].…”

Higher early than late-season residue load of pesticides in honey bee bread in Slovakia

“…Nowadays, the agriculture intensification linked with higher pesticide use means that pollinators are chronically exposed to an "agrochemical cocktail" during the season (Goulson et al 2015). Therefore, monitoring of pesticide residues, including both the lipophilic and hydrophilic active substances, in bee bread can provide us with valuable information on the use of pesticides in the environment around the colony (Schaad et al 2023) as well as on the exposure level within the colony. Nevertheless, the botanical origin of collected pollen plays an important role in the level of contamination.…”

“…Nevertheless, the botanical origin of collected pollen plays an important role in the level of contamination. Some authors observed different seasonal residue contamination profile in bee bread or pollen pellets, which mostly correlated with the flowering periods of main agricultural plants (Friedle et al 2021;Schaad et al 2023).…”