The Effects of Idrosil and Related Agents on Varroa Destructor

Abstract

The demand for an effective treatment of Varroa mite (Varroa destructor) infestation in the bee colony during the honey season is a hot topic. To find a new treatment, we looked at the ways other industries fight similar parasites. For example, in the poultry industry the red mite (Dermanyssus gallinae) is an important parasite that is effectively controlled, in order to prevent substantial (financial) damage. This mite is often controlled with agents based on silica, which damage the armour of the mite resulting in its death. Since the red mite and the Varroa mite both belong to the family of Acari their anatomy is very similar. As a result, it is likely that the mechanism of action of these agents in the red mite will show similarities with that in the Varroa mite. For this study, we used three agents, each of slightly different composition, to answer the following questions, namely 1) their effectiveness on the Varroa mite itself and 2) their effectiveness in the beehive under field conditions. Idrosil, Care 12829 and Care 12829 V are all agents based on silica, of which the latter two are combined with oxalic acid in different concentrations. In vitro, they gave promising results: 100% mortality rates were reached within 14 hours after exposure of the mites to the agents. However, using the agents in hives under field conditions, the results did not meet our expectations; use of Care 12829 resulted in 21%, Idrosil in 27% and Care 12829 V in 51% death rate of the total estimated Varroa population in the colony.