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Varroa Mite
What is it?
Varroa mites (Varroa destructor) are external parasites of bees. The mites, which are about the size of a pinhead, use specialised mouthparts to attack developing bee larvae or adult bees, resulting in deformed bees, reduced lifespan and ultimately the destruction of the colony or hive. These mites are the most important pest of honeybees around the world.
Where is it found?
Varroa mites were originally a relatively harmless parasite of the Asian honeybee. In recent decades they have adjusted to living on domestic European honeybees and have become established in most beekeeping regions of the world.
What are its effects?
Varroa mites spread naturally between bee colonies by travelling on the bees. Modern beekeeping practices of moving hives and equipment between apiary sites have the potential to spread mites quickly over long distances.
One or sometimes more female mites enter a brood cell in the bee hive laying about five or six eggs each. Newly hatched (nymph) mites feed on the growing bee larva.
Once mites reach maturity they mate, the males die; the females attach themselves to adult bees and feed by sucking their blood. A heavily infested colony may have mites on a third or more of adult bees or brood.
Attack by varroa mite weakens bees, shortens their lives, or causes death from virus infections that would otherwise cause little harm. In severely attacked colonies bees may have stunted wings, missing legs or other deformities. Unless urgent action is taken, the vitality of bees in the colony declines until all are dead.
Varroa mites can remain undetected for up to two years, by which time it is too late to prevent spread to other hives.
What’s the risk to Australia?
The most obvious threat is to Australia’s bee and honey industries. Apart from reduced honey production, apiarists would need to repeatedly treat their hives to ensure their survival.
However, the major part of the cost of varroa would probably be felt not by the honeybee industry but by other industries with crops that rely on honeybees for pollination, including almonds, avocadoes, cotton, stone fruits, pome fruit, melons and pumpkins.
Varroa mites were discovered in New Zealand in 2000 and have already had an immense economic impact, with significant control costs and losses of bees, hives, honey production, crop yields and export revenue.
Live bees can’t be imported into Australia without strict quarantine measures. Visitors must declare all bee and honey products for inspection, and some States also have their own quarantine restrictions on the movement of honey and bee products in Australia.