RESEARCH ARTICLE Phenotypic and Genetic Analyses of the Varroa Sensitive Hygienic Trait in Russian

Varroa destructorcontinues to threaten colonies of European honey bees. General hygiene, and more specific Varroa Sensitive Hygiene (VSH), provide resistance towards the Varroa mite in a number of stocks. In this study, 32 Russian (RHB) and 14 Italian honey bee colo-nies were assessed for the VSH trait using two different assays. Firstly, colonies were as-sessed using the standard VSH behavioural assay of the change in infestation of a highly infested donor comb after a one-week exposure. Secondly, the same colonies were as-sessed using an “actual brood removal assay ” that measured the removal of brood in a sec-tion created within the donor combs as a potential alternative measure of hygiene towards Varroa-infested brood. All colonies were then analysed for the recently discovered VSH quantitative trait locus (QTL) to determine whether the genetic mechanisms were similar across different stocks. Based on the two assays, RHB colonies were consistently more hy-gienic toward Varroa-infested brood than Italian honey bee colonies. The actual number of brood cells removed in the defined section was negatively correlated with the Varroa infesta-tions of the colonies (r2 = 0.25). Only two (percentages of brood removed and reproductiv