Genomic assessments of honey bee (Apis mellifera) health under different levels of Varroa mite infestations in conventional and organically-kept apiaries

The honey bee (Apis mellifera) is of critical importance to the agricultural systems in the US. Unfortunately, honey bee populations have been declining for many years. The newest disease, “Colony Collapse Disorder”, has raised concerns for the future of honey bee industry and agriculture. Possible explanations for the decline include pests and pathogens, exposure to pesticides, malnutrition, and beekeeping practices. In this study, we investigated honey bee health in two different beekeeping management practices (conventional and organically-kept apiaries). Data indicated that honey bees from conventionally-kept colonies with 0% Varroa mite infestations had an upregulation of prophenoloxidase (PPO) gene expression levels. Vitellogenin (Vg) gene expression levels were significantly higher in bees from hives with 0% mite infestations and 5-10% mite infestations from organically-kept apiaries when compared to conventionally-kept apiaries. Honey bees from conventionally managed hives with 0% mite infestations significantly down-regulated malvolio (mvl) gene expression compared to organically-kept hives. Data also indicated that the expression levels of the gene spaetzle were significantly increased in organically-kept honey bees with 5-10% mite infestations compared to conventional ones.