Impact of chronic exposure to field-level glyphosate on the gut microbiota of Apis cerana and Apis mellifera

Glyphosate (GLY) stands as one of the most extensively used pesticides globally. Although several studies have investigated the effects of sublethal doses of GLY on the gut microbiota of bees, limited information is available on how residual concentrations of GLY in bee food affect Apis cerana (Asian honey bees) and Apis mellifera (European honey bees) at different time points. To explore these effects, we employed 16S rRNA Illumina sequencing technology to evaluate the consequences of chronic GLY exposure (0.7 mg/kg, GLY residual in beebread) on the gut microbiome of A. cerana and A. mellifera on days 3 and 12 of the exposure period. Even though our findings revealed no significant difference in the microbiota abundance between control bees and GLY-treated bees on the 3rd day, GLY-treated bees exhibited 55.56 % abundance of the genus Snodgrassella (a core gut bacterium) and 4.54 % of the genus Commensalibacter (a non-core gut bacterium) compared to control bees in A. cerana and A. mellifera, respectively. In addition, our results showed that a noticeable trend indicated that the gut of A. mellifera was more susceptible to GLY than that of A. cerana. Considering the vital role of gut microbiota in the health of honey bee colonies, our results suggest that 0.7 mg/kg of GLY are likely to have adverse effects on the health of honey bees.