Single and Synergistic Effects of Microplastics and Difenoconazole on Oxidative Stress, Transcriptome, and Microbiome Traits in Honey Bees

Microplastics (MPs) and pesticides
are identified as two environmental
pollutants. In the present study, we showed evidence of toxic effects
on honey bees from chronic oral exposure to food containing difenoconazole
alone (Dif) and in a binary mixture with polystyrene (PS)-MPs (Dif
+ PS). We observed a disrupted gut microbial community structure in
bees after difenoconazole exposure, and the gut microbiota structure
richness increased at the phylum and genus levels in Dif + PS group.
Transcriptomic analysis revealed that difenoconazole exposure caused
98 differentially expressed genes (DEGs), while 41 DEGs were identified
in Dif + PS group. PS-MPs seemed to mitigate oxidative damage and
changes in the transcriptome profile in honey bees caused by difenoconazole
to some extent. However, coexposure increased the disordered microbial
community composition. Our study highlights the importance of investigating
possible additive and synergic activities between stressors to comprehensively
understand the effects of pollutants on pollinating insects.