Researchers in Argentina conducted a field study to assess the fate of ingested microplastics within honeybee hives, and explore whether chronic exposure to microplastic fibres affected population growth.
The researchers fed colonies with sucrose solutions for one month, that were either untreated or treated with 50 mg of polyester microfibers/litre. Samples of adults, larvae, wax and honey were collected and analysed under a digital microscope, where the number of the polyester microfibres were recorded. To test whether exposure to microplastics affected population growth and/or productivity, the number of frames used by bees, number of interframes covered with adult bees, total brood area and honey reserves in each hive were estimated.
The researchers found that the microplastic fibres (MF) from the treated syrup were incorporated by adult worker bees, remaining in their cuticle, digestive tract, larvae, honey, and wax. Most of the microplastics were accumulated in wax (32,000 MF/kg) compared to the bees digestive tract or honey (670 MF/kg), suggesting that most of the microplastics were excreted or transferred to the wax. The researchers highlight that because wax is recycled, microplastics could therefore accumulate in hives. The amount of microplastics found in the honey of treated hives was like that found in commercial honey, suggesting that honeybees might be exposed to similar microplastic contamination levels in the environment.
The researchers found that the one month of exposure to the microplastics did not cause apparent toxic effects. There were no statistically significant differences between hives fed with microfibres and the control in terms of the number of frames used, number of frames covered with bees, brood area or honey reserves.
Read the paper:
Alma, A.M., de Groot, G.S. & Buteler, M. (2023) Microplastics incorporated by honeybees from food are transferred to honey, wax and larvae. Environmental Pollution, 320, 121078. https://doi.org/10.1016/j.envpol.2023.121078