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Microplastics reach the brain and interfere with honey bee cognition
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Scientists fed honey bees microplastics at concentrations found in the environment and discovered that the particles reached the bees' brains by crossing the blood-brain barrier. The microplastics impaired the bees' ability to taste sugar, learn, and form memories, with polystyrene having the most severe effects. This research is concerning because it shows microplastics can cross into the brain of a living organism and directly affect cognitive function, raising questions about similar effects in other species.
Scientific research on the impact of microplastics (MPs) in terrestrial systems is still emerging, but it has confirmed adverse health effects in organisms exposed to plastics. Although recent studies have shown the toxicological effects of individual MPs polymers on honey bees, the effects of different polymer combinations on cognitive and behavioural performance remain unknown. To fill this knowledge gap, we investigated the effects of oral exposure to spherical MPs on cognitive performance and brain accumulation in the honey bee Apis mellifera. We evaluated the acute toxicity, after a two-day exposure, of polystyrene (PS - 4.8-5.8 μm) and plexiglass (Poly(methyl methacrylate), or PMMA - 1-40 μm) MPs, and a combination of the two (MIX), at two environmentally relevant and one higher concentration (0.5, 5 and 50 mg L) and analysed their effects on sucrose responsiveness and appetitive olfactory learning and memory. We also used fluorescent thermoset amino formaldehyde MPs (1-5 μm) to explore whether microspheres of this diameter could penetrate the insect blood-brain barrier (BBB), using Two-Photon Fluorescence Microscopy (TPFM) in combination with an optimized version of the DISCO clearing technique. The results showed that PS reduced sucrose responsiveness, while PMMA had no significant effect; however, the combination had a marked negative effect on sucrose responsiveness. PMMA, PS, and MIX impaired bee learning and memory in bees, with PS showing the most severe effects. 3D brain imaging analysis using TFPM showed that 1-5 μm MPs penetrated and accumulated in the brain after only three days of oral exposure. These results raise concerns about the potential mechanical, cellular, and biochemical damage that MPs may cause to the central nervous system.
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Microplastics reach the brain and interfere with honey bee cognition
AI summary Read the abstract
Researchers found that polystyrene and plexiglass microplastics can reach the brains of honey bees and disrupt their cognitive function, impairing sucrose responsiveness and appetitive olfactory learning and memory at environmentally relevant concentrations.
Microplastics reach the brain and interfere with honey bee cognition
AI summary Read the abstract
Researchers found that microplastics reach honey bee brains and impair cognitive function, with bees exposed to mixed polymer combinations showing disrupted learning and memory abilities, demonstrating that plastic pollution poses a direct threat to pollinator health.
Acute and chronic ingestion of polyethylene (PE) microplastics has mild effects on honey bee health and cognition
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Researchers tested how ingesting polyethylene microplastics affected honey bee survival, feeding, and cognitive abilities at different concentrations and exposure lengths. The study found that high concentrations increased bee mortality and altered feeding behavior, but learning and memory remained largely intact. These results suggest that while bees are not completely unaffected by microplastic ingestion, the cognitive impacts appear relatively mild compared to other health effects.
Crossing barriers – tracking micro- and nanoplastic pathways into the human brain
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Researchers tracked potential pathways by which micro- and nanoplastics may enter the human brain, examining both in vitro cell models and post-mortem brain tissue. They found that human monocytes rapidly internalized polystyrene particles into endocytic vesicles and mitochondria, and detected plastic particles in brain tissue samples, providing evidence that nanoplastics may be capable of crossing brain barriers.
Microplastics incorporated by honeybees from food are transferred to honey, wax and larvae
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Researchers found that when honeybees consume food contaminated with microplastics, the particles are transferred to honey, beeswax, and developing larvae inside the hive. Chronic exposure did not significantly affect colony growth, but the presence of microplastics in honey means humans may be ingesting them through this food source. This study reveals another pathway by which microplastics can enter the human diet through contaminated bee products.
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