Synergistic effects between microplastics and glyphosate on honey bee larvae

Area of Science:

• Environmental Science
• Ecotoxicology
• Apiculture Science

Background:

• Microplastic (MP) pollution is a growing global concern.
• The combined impact of MPs and glyphosate (GLY) on honey bee health is largely unknown.
• Honey bees are vital pollinators facing numerous environmental stressors.

Purpose of the Study:

• To investigate the effects of MPs and GLY, alone and in combination, on honey bee larvae.
• To assess impacts on larval development, gene regulation (detoxification, antioxidant, immune), and oxidative stress.
• To determine if MPs and GLY exhibit synergistic effects on honey bees.

Main Methods:

• Honey bee larvae were exposed to varying concentrations of MPs and GLY.
• Larval survivorship and weight were measured.
• Gene expression of key detoxification, antioxidant, and immune markers was analyzed.
• Activity of oxidative stress biomarkers, such as catalase, was assessed.

Main Results:

• Combined exposure to MPs and GLY significantly decreased honey bee larvae survivorship and weight.
• Exposure to MPs alone did not result in significant differences in larval development.
• Both MPs and GLY downregulated the defensin-1 gene.
• Combined exposure uniquely downregulated hymenoptaecin and increased catalase activity, indicating synergistic effects.

Conclusions:

• Microplastics and glyphosate exhibit synergistic toxicity towards honey bee larvae.
• The combination leads to immunosuppression and reduced larval survival and weight.
• These findings highlight the potential ecological risks posed by co-occurring environmental pollutants to vital pollinators.