Insecticides Cause Transcriptional Alterations of Endocrine Related Genes in the Brain of Honey Bee Foragers

Bees are exposed to endocrine active insecticides. Here we assessed expressional alteration of marker genes indicative of endocrine effects in the brain of honey bees. We exposed foragers to chlorpyrifos, cypermethrin and thiacloprid and assessed the expression of genes after exposure for 24 h, 48 h and 72 h. Chlorpyrifos caused the strongest expressional changes at 24 h characterized by induction of vitellogenin, major royal jelly protein (mrjp) 2 and 3, insulin-like peptide (ilp1), alpha-glucosidase (hbg3) and sima, and down-regulation of buffy. Cypermethrin caused minor induction of mrjp1, mrjp2, mmp1 and ilp1. The sima transcript showed down-regulation at 48 h and up-regulation at 72 h. Exposure to thiacloprid caused down-regulation of vitellogenin, mrjp1 and sima at 24 h, and hbg3 at 72 h, as well as induction of ilp1 at 48 h. The buffy transcript was down-regulated at 24 h and up-regulated at 48 h. Despite compound-specific expression patterns, each insecticide altered the expression of some of the suggested endocrine system related genes. Our study suggests that expressional changes of genes prominently expressed in nurse or forager bees, including down-regulation of buffy and mrjps and up-regulation of hbg3 and ilp1 may serve as indicators for endocrine activity of insecticides in foragers.