Attack of the dark clones the genetics of reproductive and color traits of South African honey bees (Apis mellifera spp.)

Abstract

The traits of two subspecies of western honey bees, Apis mellifera scutellata and A.m. capensis, endemic to the Republic of South Africa (RSA), are of biological and commercial relevance. Nevertheless, the genetic basis of important phenotypes found in these subspecies remains poorly understood. We performed a genome wide association study on three traits of biological relevance in 234 A.m. capensis, 73 A.m. scutellata and 158 hybrid individuals. Thirteen markers were significantly associated to at least one trait (P ≤ 4.28 × 10−6): one for ovariole number, four for scutellar plate and eight for tergite color. We discovered two possible causative variants associated to the respective phenotypes: a deletion in GB46429 or Ebony (NC_007070.3:g.14101325G>del) (R69Efs*85) and a nonsense on GB54634 (NC_007076.3:g.4492792A>G;p.Tyr128*) causing a premature stop, substantially shortening the predicted protein. The mutant genotypes are significantly associated to phenotypes in A.m. capensis. Loss-of-function of Ebony can cause accumulation of circulating dopamine, and increased dopamine levels correlate to ovary development in queenless workers and pheromone production. Allelic association (P = 1.824 x 10−5) of NC_007076.3:g.4492792A>G;p.Tyr128* to ovariole number warrants further investigation into function and expression of the GB54634 gene. Our results highlight genetic components of relevant production/conservation behavioral phenotypes in honey bees.

Roles of DNA Methylation in Color Alternation of Eastern Honey Bees (Apis cerana) Induced by the Royal Jelly of Western Honey Bees (Apis mellifera)

“…Knocking out the yellow-y gene induced a reduction in the amount of black pigment in worker bees’ cuticles, while the expression of Amyellow-y and aaNATA in mutant drones, which have a dramatic body pigmentation defect, was lower than in wild-type drones [ 46 ]. Previous research indicated that the ebony gene contributes to the diverse body color variation of honey bees, suggesting that genes like ebony might be evolutionarily selected and vary in different bee species or subspecies resulting in distinct body colors [ 47 ]. Therefore, the regulation of body color in honey bees not only depends on the key pathways for melanin synthesis but can also be influenced by other conserved body-color-related genes.…”

Quantifying Abdominal Coloration of Worker Honey Bees

“…The influence of environmental temperature on abdominal coloration in honey bees could also be observed on a subspecies level. Rosa et al [33] described lighter color in Apis mellifera scutellata, which live in warm and arid climates, in comparison to Apis mellifera capensis, which live in the Mediterranean climate with wet winters. Gruber et al [9] reported similar observations: the morphometric properties of honey bees in Ethiopia vary with altitude.…”

Honey bee functional genomics using symbiont-mediated RNAi

“…Collect bee workers from apiary 34. Collect bees according to one of two methods: (1) Allow adult bees to emerge from the frame (1 day) or (2) Pull pupae and allow bees to develop in plastic brood chambers (3-4 days). Method 1 can be performed on the same day as step 33, whereas method 2 should be initiated 3-4 days prior.…”

“…Despite this widespread use and economic importance, genetic tools for bees are underdeveloped. Most studies to date have examined differences in phenotypes due to natural genetic variation or how gene expression changes after an experimental treatment [1][2][3][4] .While these studies can suggest candidate genes involved in different biological processes and pathways, they are correlative and cannot rigorously establish that changes in gene expression cause a change in behavior or other phenotypes. Disrupting or lowering the expression of a target gene and observing the corresponding phenotypic effects is a fundamental approach for establishing gene function.…”