Unravelling the microplastic menace: Different polymers additively increase bee vulnerability.

Area of Science:

• Environmental Science
• Toxicology
• Entomology

Background:

• Microplastics (MPs) are pervasive pollutants with largely unknown effects on non-target organisms.
• Most research focuses on single polymer toxicity, not realistic environmental mixtures.
• Pollinating insects like honey bees (Apis mellifera) are vital but vulnerable to environmental contaminants.

Purpose of the Study:

• To assess the lethal and sublethal effects of polystyrene (PS) and poly(methyl methacrylate) (PMMA) microplastics, individually and combined, on honey bees.
• To investigate the impact of MPs on honey bee immune response, survival, and cuticular hydrocarbon profiles.
• To determine if MP-induced chemical profile changes affect social recognition behaviors and colony integrity.

Main Methods:

• Oral administration of PS and PMMA MPs at varying concentrations (0.5, 5, 50 mg/L) to honey bees.
• Evaluation of bee survival rates and immune system markers.
• Gas chromatography-mass spectrometry (GC-MS) analysis of cuticular hydrocarbons.
• Behavioral assays assessing social recognition and colony entry.

Main Results:

• Both PS and PMMA MPs exhibited additive negative effects on bee survival and immune response, even at ecologically relevant concentrations.
• MP exposure, particularly PMMA, altered cuticular hydrocarbon profiles, reducing the abundance of key compounds.
• Bees exposed to MPs were not rejected by colony guards, allowing undetected entry and potential spread of contamination.

Conclusions:

• Microplastic pollution poses a significant threat to honey bee health and colony stability.
• Additive toxicity and altered chemical signaling present risks to individual bees and the entire colony.
• The undetected entry of contaminated foragers highlights a critical pathway for microplastic dissemination within hives.