Tasmania is currently free of varroa. If varroa were to enter and establish in Tasmania, the impacts to commercial beekeepers, recreational beekeepers, home gardeners, and pollination dependent horticultural and agricultural industries would be significant. The establishment of varroa in Tasmania would also have a devastating impact on wild honey bee colonies throughout the state with the potential to reduce wild populations by around 95% as has been observed in other countries. This would practically eliminate the free pollination services provided to horticultural/agricultural industries and home gardeners from wild honey bees.
To prevent the entry of varroa into Tasmania, restrictions on the import of bees, apiary products and used apiary equipment have been in place since the detection in NSW in June 2022. These import restrictions will be reviewed once the transition to management plan has been finalised. See more information on the General Biosecurity Direction.
Varroa mites only produce offspring when the honey bee brood is present in hives.
A mated female varroa mite will enter a brood cell (drone cells preferred) containing mature larvae just before the cell is capped by hive bees. The female varroa then moves to the base of the cell and submerges herself in the larval food. When the cell is capped, the submerged varroa begins feeding.
Above: Varroa destructor mite on a bee pupa. Image: Gilles San Martin - Wikimedia Commons
Individual females lay up to six eggs, starting about 60 to 70 hours after the cell was capped and thereafter at intervals of about 30 hours. The first egg laid is male and the others are female. Eggs are laid on the base and walls of the cell, and sometimes on the developing bee.
Female varroa mites take around 8 to 10 days to develop from an egg to an adult. The long interval between the laying of individual eggs means that mites can be at different stages of development in the one cell. Protonymphs hatch from the eggs about 12 hours after being laid. A larger duetonymph stage occurs before the final adult stage.
The single male varroa mates with its sisters while they are in the brood cell.
When the new adult bee emerges from its cell, the young female mites and mother mite also leave the cell, often on the emerging bee.
How varroa spreads
The mites are very mobile and readily transfer between adult bees.
Varroa spreads between colonies and apiaries when hive components, infested brood and adult bees are interchanged during normal apiary management practices. Beekeepers can spread varroa by moving hives, used beekeeping equipment and queen bees.
Foraging and drifting bees and swarms can also spread varroa. Mites can move from a forager bee to a flower, and then hitch a ride on another bee or insect visiting the same flower.
Varroa is not spread in honey.