The predatory mite Stratiolaelaps scimitus to combat varroa mites (Varroa destructor) in apiaries - risk to biodiversity
Report no: 2023:6
Using the predatory mite Stratiolaelaps scimitus as a biological control agent to combat the varroa mite (Varroa destructor) in beehives will not pose a risk to Norwegian biodiversity, according to a risk assessment carried out by VKM for the Norwegian Environment Agency.
Stratiolaelaps scimitus, also sold under the name Hypoaspis miles, is a predatory soil mite that has been used for several decades in Norway, primarily to control dark-winged fungus gnats that damage the roots of commercial crops grown in greenhouses and polytunnels. The Norwegian Environment Agency has received an application for a new use, specifically to combat the varroa mite in beehives.
Varroa mites live on honeybees. They are considered one of the greatest threats to beekeeping because they are parasitic and can transmit a variety of viral and bacterial diseases to honeybees.
Results and conclusions
VKM has evaluated whether the new use of the predatory mite to combat varroa mites in beehives could have negative consequences for Norwegian biodiversity, considering future climate change.
“It is not more likely that Stratiolaelaps scimitus will establish itself and spread in the Norwegian nature as a result of its use in beehives, beyond the likelihood that already follows from its current use," says Anders Nielsen, scientific leader of the project.
VKM emphasizes that there is nothing to indicate that decades of use of Stratiolaelaps scimitus in Norway has led to the predatory mite establishing populations outside of the areas where it has been introduced.
Future climate change will not alter the conclusion. The optimal temperature for mite reproduction is significantly higher than what is normal in Norway (around 28° C).
“Despite reports that the mite can survive down to –5° C, it would not be able to establish permanent populations in Norway”, confirms Nielsen.
The risk assessment has been approved by the VKM Panel on Biodiversity.