Synergistic effects between microplastics and glyphosate on honey bee larvae

Microplastic (MPs) pollution has emerged as a global ecological concern, however, the impact of MPs exposure, particularly in conjunction with other pollutants such as glyphosate (GLY) on honey bee remains unknown. This study investigated the effects of exposure to different concentrations of MPs and their combination with GLY on honey bee larvae development, or during the larvae period, regulation of major detoxification, antioxidant and immune genes, and oxidative stress biomarkers. Results revealed that combined exposure to MPs and GLY decreased larvae survivorship and weight, while exposure to MPs alone showed no significant differences. Both MPs and GLY alone downregulated the defensin-1 gene, but only combined exposure with GLY downregulated the hymenoptaecin gene and increased catalase enzyme activity. The data suggest a synergistic effect of MPs and GLY, leading to immunosuppression and reduced larvae survival and weight. These findings highlight potential risks of two prevalent environmental pollutants on honey bee health.