Global transcriptome analysis reveals relevant effects of environmentally relevant concentrations of cypermethrin in honey bees (Apis mellifera)

Abstract Cypermethrin is a frequently used pyrethroid in agriculture and households but its chronic and molecular effects remain elusive. Here we describe effects of sublethal cypermethrin exposure on the global transcriptome in the brain of honey bees by RNA-sequencing. Exposure for 48 h to 0.3 ng/bee cypermethrin (3 ng/mL sucrose solution) reveals 38 differentially expressed genes (DEGs), of which 29 are up-regulated and 9 down-regulated. Exposure to 3 ng/bee causes differential expression of 265 DEGs (209 up-, 56 down-regulated). Among the 24 DEGs prominently induced by both concentrations are genes encoding muscular structure, muscular processes and esterase B1. Functional analysis (GO term analysis) confirms the enrichment of muscular development, structure and function among the 89 and 35 significantly altered GO terms at the low and high concentration, respectively. Up-regulation of nine DEGs determined by RT-qPCR showed a good correlation with RNA-sequence data. Among them are genes including esterase B1, titin, twitchin, mucin-19, insulin like growth factor binding protein, golgin like protein and helix loop protein. Our study demonstrates for the first time molecular effects at environmental concentrations of cypermethrin including expressional induction of genes encoding muscular and cellular processes and metabolism enzymes. Further studies should demonstrate physiological consequences in bees.