Vetnews | Mei 2025 12 « BACK TO CONTENTS interactions between MPs and other pollutants to fully assess their impact on bee health and colony sustainability. Bashir et al. (2024) also highlight some limitations associated with the collection, processing, and analysis of samples: (1) Collection: sample size and foraging patterns; (2) Processing: control of matrix contamination and interference; (3) Analysis: limits of detection and identification of particles; (4) Methodological standardization: lack of standardized protocols and interlaboratory variability. They suggest points that need more attention in future studies: interaction with other stressors, ecological impacts, developments of detection methods, nano-plastic interaction, omics approaches, and nanoecotoxicology. Bees as bioindicators of contamination by MPs Edo et al. (2021) tested the hypothesis that A. mellifera workers can carry microplastics from their foraging area back to the nest, which is variable, but can reach up to 10 km (Beekman and Ratnieks 2001; Couvillon et al. 2015), to verify whether this species can function as bioindicators of contamination by microplastics in urban, peri-urban, and rural areas. The study indicated the presence of microplastics in all sampled sites, which are mainly in the form of fragments (52%) and fibres (38%), with average equivalent diameters of 64 ± 39 µm for fibres and 234 ± 156 µm for fragments. The authors conclude by pointing out that the results prove the presence of microplastics, and materials of anthropogenic origin adhered to the bristles (body) of bees, which allows their use as active bioindicators of this contaminant. Edo et al. (2021) also highlight that their work demonstrated for the first time the possibility of using the species A. mellifera as a bioindicator of microplastics in the environment. Rodrigues et al. (2024) evaluated the presence of particulate matter (MPs) in A. mellifera workers across different environmental settings: urban, peri-urban, and rural areas. The bees were collected in collaboration with beekeepers in the municipality of Piedade, São Paulo, Brazil. The laboratory procedures were divided into two phases: Phase I involved analyzing external particles, those adhered to the bristles and bodies of the workers and, Phase II focused on analyzing internal particles, those present in the digestive tract of the workers. At the end of both laboratory phases, the particles found were classified by shape, colour, and size. A total of 507 particles were identified across the three areas: 307 fibres, 137 fragments, and 61 filaments. In the urban area, 76 particles were found, 190 particles in the peri-urban area, and 241 particles in the rural area. Subsequently, 30 spectra were obtained—10 from each area—using a Renishaw in Via Micro-Raman spectrometer (785 nm) in the spectral range of 1800–400 cm⁻1, with a resolution of 4 cm⁻1, an exposure time of 10 s, and 4 accumulations, to chemically characterize the particles found. Among the spectra obtained across the three areas, 13 particles were identified as polyethylene terephthalate (PET), 11 as polyamide (PA), 4 as polyethylene (PE), 1 as polyester (PL), and 1 as polyvinyl chloride (PVC). The authors suggest that the large number of particles found in less urbanized areas is likely due to the transport of MPs from their places of origin, carried by air masses and other means, allowing these contaminants to be deposited in more remote locations. They also conclude that A. mellifera workers are effective bioindicators of MP contamination in both terrestrial and airborne environments and that they act as airborne vehicles for these contaminants during their foraging activities. In urban areas, the workers were found to have a greater number of internal particles, indicating that these bees may have begun to incorporate unnatural resources into their habits. The authors further emphasize the importance of future studies to understand the consequences of ingesting these particles, particularly considering the capacity of MPs to adsorb other contaminants, which often coexist in the environment. In the review article by Cunningham et al. (2022), honeybees are considered bioindicators of environmental contaminants, pathogens, and climate change. Within the theme of environmental contaminants, the authors discuss persistent chemicals and particulate matter in the air, including MPs. Therefore, the authors define MPs as an emerging class of air pollutants that have effects on human health, as they are particles easily transported over long distances by wind and other vectors, such as animals, which can play a role as a catalyst for climate change. Thus, quantification of pollutants and persistent chemicals in bees and parent hives can help to identify potential target areas in which more significant remediation efforts or reductions in emissions of such pollutants are needed. MPs‑insecticides interaction Xue et al. (2024) analyzed the toxic effects of nano-polystyrene (nanoPS) and the insecticide cyfluthrin (Cy) on Apis cerana cerana Fabricius workers, both individually and in combination. NanoPS was tested at concentrations of 0.5, 5, and 50 mg/L, while the insecticide was used at a concentration of 0.2 mg/L, both diluted in a 50% sucrose solution. After 15 days of exposure, pathological analyses of the midgut, qPCR, biochemical tests, and intestinal metabolomic analysis were conducted. The results showed a significant reduction in the survival rate in the group treated with Cy (p < 0.01) compared to the control group. In the other groups, the survival rate also decreased, but the difference was not statistically significant. Regarding the intestinal analysis, the nanoPS and nanoPS + Cy groups exhibited rupture and disappearance of the intestinal basement membrane, a reduction in the number of cell nuclei, a decrease in the size of epithelial cells, and thinning of the intestinal wall. Additionally, there was an increase in the expression of the Cyp9Q1 gene in the NanoPS + Cy group, though this increase did not reach statistical significance. On the other hand, the expression of the P450 9e2 gene was significantly higher in the NanoPS and Cy groups compared to the control group. Metabolomic analysis revealed that MPs affect amino acid and ester metabolism in A. cerana cerana, likely leading to inhibition of pharyngeal gland development and downregulation of immune gene expression. The authors conclude that it is essential to understand the interactions between nanoPS and pesticides, as well as their effects on pollinators, to promote environmental protection and sustainable agriculture. Leading Article
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