Data for: Breeding honey bees (Apis mellifera L.) for low and high Varroa destructor population growth: gene expression of bees performing grooming behavior

Background Social organisms, including honey bees (Apis mellifera L.),
have defense mechanisms to control the multiplication and transmission of
parasites and pathogens within their colonies. Self-grooming, a mechanism
of behavioral immunity, seems to contribute to restraining the population
growth of the ectoparasitic mite Varroa destructor in honey bee colonies.
Because V. destructor is the most damaging parasite of honey bees,
breeding them for resistance against the mite is a high priority of the
beekeeping industry. We conducted a bidirectional breeding program to
select honey bee colonies with low and high varroa population growth (LVG
and HVG, respectively). Having high and low lines of bees allowed the
study of genetic mechanisms underlying self-grooming behavior between the
extreme genotypes. Worker bees were classified into two categories: ‘light
groomers’ and ‘intense groomers’. The brains of bees from the different
categories (LVG-intense, LVG-light, HVG-intense, and HVG-light) were used
for gene expression and viral quantification analyses. Results
Differentially expressed genes (DEGs) associated with the LVG and HVG
lines were identified, including four odorant-binding proteins and a
gustatory receptor. A functional enrichment analysis showed 19 enriched
pathways from a list of 219 down-regulated DEGs in HVG bees, including the
Kyoto Encyclopedia of Genes and Genomes (KEGG) term of oxidative
phosphorylation. Additionally, bees from the HVG line showed higher levels
of Apis rhabdovirus 1 and 2, Varroa destructor virus -1 (VDV-1), and
Deformed wing virus-A (DWV-A) compared to bees of the LVG line.
Conclusions The difference in expression of odorant-binding protein genes
and a gustatory receptor between bee lines suggests a possible link
between them and the perception of irritants to trigger rapid
self-grooming instances that require the activation of energy metabolic
pathways. Therefore, our results provide new insights into the molecular
mechanisms involved in honey bee grooming behavior. Differences in viral
levels in the brains of LVG and HVG bees showed the importance of
investigating the pathogenicity and potential impacts of neurotropic
viruses on behavioral immunity. The results of this study advance the
understanding of a trait used for selective breeding, self-grooming, and
the potential of using genomic-assisted selection to improve breeding
programs.