Vetnuus | May 2025 15 issues such as a false sense of satiety, damage to the digestive tract lining, and localized ulcerations. These effects are similar to those observed in marine animals exposed to microplastics, as reported in previous studies by de Barros et al. (2020) and Cole et al. (2011). The researchers conclude that the observed reduction in body weight due to chronic exposure to PS-MP could, in the long term, lead to an increased mortality rate within the bee colony. This heightened mortality could subsequently impact reproductive activity, indirectly affecting the crucial ecological services provided by bees, such as pollination. Furthermore, the authors emphasize the findings of studies like Wang et al. (2022), which demonstrated an increase in the reproduction of the bacteria Hafnia alvei in the bee gut following the induction of PS-MP (100 nm). This bacterial proliferation could facilitate the spread of pathogenic bacteria from the digestive tract to the hemolymph, thereby further increasing mortality rates within the colony. Foraging behaviour Buteler et al. (2022) analyzed the effects of acute exposure to microplastic fibres on foraging behaviour in A. mellifera carnica. The researchers concluded that although mortality does not occur after acute ingestion, the foraging behaviour does not prevent bees from consuming contaminated food, which may cause long-term lethality since. Adaptive behaviour MacIvor and Moore (2013) described the use of polyurethane and polyethylene in the construction of nests and closing of brood cells of two species of megachilid bees (M. rotundata and M. campanulae). The analyses allowed us to identify that both species’ collected compounds resemble the natural materials used in the construction of their nests; M. rotundata, which normally collects fragments of plant leaves, has been observed building its nests with pieces of polyethylene plastic bags, while M. campanulae, which normally collects resins from trees and plants, was observed building its nest with a type of external sealant, used in constructions, whose base consists of polyurethane. The authors highlight that although this collection is possibly accidental, it may represent an indication of the appearance of ecologically adaptive characteristics, which aim at the survival of these species in an environment increasingly occupied and degraded by humans. One of the consequences observed by such adaptation is related to the adhesion between the brood cells, provided by the chewing of the leaves collected by this species; the absence of the pulp generated by chewing resulted in the absence of adhesion of these particles to the pieces of leaves that were already inside the nests, thus affecting the architecture of these cells. Regarding M. rotundata, the authors observed that the collection of these contaminants does not seem to be random or unintentional, since the bees deposited such particles at the bottom of each cell and returned to collect leaves, which were used in the closure of the cells; thus, the authors consider that the collection of plastic is not related to the absence of natural material and that there may be advantages in the use of these materials, such as avoiding the presence of natural parasites of these species. However, despite the observations, the authors warn that the presence of these compounds may have negative consequences for the development of nests, but that they were not identified during this specific experiment. Incorporation of MP by bees and the transfer to honey, wax, and larvae within colonies Alma et al. (2023) analyzed the incorporation of MP by bees through their feeding and the transfer of these particles to honey, wax, and larvae within colonies. For this, the authors fed 16 colonies of A. mellifera carnica with a sucrose solution (2:1) and 50 mg of blue polyester microfibers (MF) per litre of solution, since this concentration is based on the actual number of microfibers found in drinking water, according to FAO studies (2022). One month after the start of feeding, samples of adult bees, larvae, wax, and honey were collected. The MF present in the body of adult bees (30 to 65 individuals) were analyzed following the procedures described by Edo et al. (2021); approximately 20 of these individuals had their stomach contents analyzed. For the larvae, at least 2 replicates of 20 closed brood cells from each colony were sampled, which were dissected for MF evaluation. After the analyses, the authors concluded that the MFs were incorporated by the adult worker bees and remained in their bristles and digestive tract, as well as in the other matrices of the hive, indicating that the adult bees that feed on sugar solutions contaminated by MP can disperse them throughout the colony. The authors also point out that a greater proportion of MF was found in wax than in the other matrices of the hive, which was justified by the authors as a result of the hydrophobic characteristic of the PMs; a smaller number of MF was also found in the digestive tract of dissected bees, as well as in honey (670 MF/kg) compared to wax (32,000 MF/kg). All these results suggest that most of the particles are excreted or transferred to the wax. The authors warn that the experimental design used does not allow for to identification of how the transfer of microfibers to the wax occurs. They assume that MFs are adsorbed into the bristles of the body and thus transferred to the wax in the form of scales, which are released from the abdomen. The authors also point out that since they found a high concentration of MFs in the wax when compared to other matrices, raises the concern regarding the potential accumulation of MP inside the hives. Since the wax represents the construction base of these structures, and since the plastic does not degrade and the wax is continuously recycled, these particles could persist in the hives with an accumulative potential, increasing the concentration of particles to which the bees are exposed throughout their lives. Incorporation of microplastics or nanometals via larval ingestion The paper of Viana et al. (2023) tested toxicity via ingestion of polystyrene microparticles (500 ng/bee), polyethylene terephthalate (500 ng/bee), and metal oxide nanoparticles (titanium dioxide, 10 µg/bee) in P. helleri bee larvae, reared in vitro. The authors found Leading Article
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