Wintering losses of honeybee colonies

Prof Stephen Martin (

A previous study conducted with Devon beekeepers found a significant number of over-wintering colony deaths were associated with elevated levels of DWV, especially when compared with the colonies that survived the winter. This phenomenon potentially explains the doubling in UK over wintering losses of honeybee colonies since the establishment of Varroa in 1990’s, since this pattern has also been mirrored across Europe and North America.

It remains unclear why the vast majority of colonies are able to carry a high level of DWV infection but appear to remain healthy so long as Varroa levels are controlled. However, if Varroa is not controlled then the colony will die.

This is why the number one honeybee pest in the UK continues to be the Varroa mite and it is the top priority of the British Beekeepers’ Association (BBKA) research wish list and hence they are providing some finical assistance.

The aim of the studentship is to study the key drivers behind the increase in over-wintering honeybee colony losses in the UK. Although this research will focus principally on the role of DWV, as we already have strong evidence that this is one of the key drivers, we will also investigate other potential drivers, such as the presence/absence of other honeybee viral pathogens such as SPV and IAPV-APV, the microsporidia fungal pathogens Nosema ceranae and N. apis, and Varroa infestation levels.

As it is impossible to predict if a colony will survive the winter or not the basic experimental design is to sample 120-150 colonies belonging to BBKA members during the winter, but only conducting the time consuming molecular and microscopic analysis on selected sub-sample of colonies that compares equal numbers of surviving and dead colonies at several locations across the UK. This information will feed into the larger annual BBKA over-wintering colony loss survey and help understand the key drivers that explain this increase, and in turn will help inform beekeepers what actions are required in order to help reduce their over-wintering colony losses.