In recent years, the varroa mite (Varroa destructor) has become the most widespread and devastating pest of Western honey bees (Apis mellifera), and has even been attributed to Colony Collapse Disorder (CDC). The varroa has two stages; one, in which it acts as a parasite to adult worker bees, and another where it reproduces and feeds within a developing brood cell. In its phoretic stage, adults seek out and attach themselves to the back of adult bees and feed. It can move throughout the hive by hopping from bee to bee as they move about the hive. In the varroa’s reproductive stage, adult females will enter the brood cells before they are “capped off” and lays eggs. Once the larvae emerge, they feed on the developing brood larva and emerge as adults. Mite populations can increase 800 times the rate of the honey bee population in warm weather, year-round brood colonies; eventually destroying the entire colony.
Research done at the Niagara Beeway shows the effectiveness of Stratiolaelaps scimitus Womersley (formerly Hypoaspis miles) against the varroa mite in honey bee hives. Stratiolaelaps is typically a soil dwelling mite that feeds on small insects and mites. You can learn more about Stratiolaelaps here.
While Stratiolaelaps is typically a soil dwelling mite, the research showed effectiveness when released directly into hives, without causing harm to the bees. In the study, the Stratiolaelaps in the peat/vermiculite mixture was poured right on top of the hive. Although they did not consume the whole varroa mite, Stratiolaelaps would tear the limbs and head parts off, successfully making the varroa inactive. It is important to note that the Stratiolaelaps will not kill the entire varroa population; however the numbers get so low that it is not a threat to the brood. While the chemically treated hives (using formic acid) wipe out the entire population at first, the varroa was back in the hives a few months later. In addition, not only is this method potentially harmful to the bees, but future varroa populations may build up a resistance, requiring a cycle of more and more chemicals to obtain the same control. While the biologically treated hives may not completely wipe out the varroa, the numbers stay consistently low and manageable.
Additional benefits have also been seen in hives treated with Stratiolaelaps. There was much more activity in the hives treated biologically. Those hives also had significantly better hygiene (less dirt, spiders, webbing, etc.). For the future, Stratiolaelaps may be looked at to control the small hive beetle. This is still being studied and tested, so if you do notice results with the small hive beetle, please let us know!
For optimal control, 150 ml of Stratiolaelaps (including the peat/vermiculite mixture, measured directly from the container) should be shaken over the top of the hive. At first, the bees may ignore the “mess”, but more experienced hives show worker bees helping move the mixture around at a faster rate. These inoculations should be applied twice a year, once in the spring and once in the late summer.
See below: two videos from Niagara Beeway showing background information on both Stratiolaelaps and the Varroa Mite, as well as film of the study and interactions between the two mites. (Note: HAM SS= Stratiolaelaps)