Tangled in natural and synthetic microfibers: prevalence, grooming, and spread across honeybees

Plastic and microplastic (MP) pollution have emerged as a global environmental and health concern. Among these contaminants, textile microfibers (MF) constitute a major proportion of MP pollution. This study examines the presence of synthetic and natural MF in Apis mellifera bees and honey across Argentina, analyzing forager and nurse bees in three provinces and honey from multiple sources. Additionally, we investigated grooming behavior upon plastic microspheres and MF exposure as the transfer of these microplastics between exposed and cleaned bees. We detected similar levels of MF contamination in forager (206 MF) and nurse bees (186 MF). Honey samples were also contaminated (12.3 ± 8.67 MF in 500 g) and no correlation between population density and number of MF was found. Raman spectroscopy identified the origin of these MF as including both natural (cotton and wool) and synthetic (polyethylene terephthalate and polyacrylonitrile) MF. We also identified several dyes in the MF: anthraquinone-based pigments, copper-based phthalocyanines, and Indigo blue, which are commonly used to color synthetic polymers and natural fibers. Grooming frequency was significantly higher for bees exposed to plastic microspheres than for those exposed to MF. Additionally, our findings confirmed the transfer of both MF and microspheres from contaminated to clean bees, highlighting a potential pathway for MP dispersion inside hives. This work underscores the urgency of comprehensively addressing synthetic microplastics and natural textile fibers in ecosystems, and their long-term ecological implications given their risks to honeybee health, pollination efficiency, and food safety.