Varroa mites in Australia.
To date, Australia remains free of the parasitic mite, Varroa destructor, which has spread rapidly across the rest of the globe since the early 1960s. The mite can reproduce in European Honey Bee drone and worker brood and has decimated bee colonies wherever the two species have come into contact. European Honey Bees (Apis mellifera) have little natural defence against the mite, and although some control measures have been successful, these focus on reduction rather than eradication, and the mites remain a serious threat. Some sense of the devastating scale of the potential impact of Varroa mites in this country can be deduced from the fact that honey bees are instrumental in contributing $4-6 billion to our economy every year. In addition to the production of honey, a large percentage of commercial crops are reliant upon the bees for pollination.
Australia’s island status should not be viewed as insurance against incursions by the mite, as New Zealand and Hawaii both fell victim to the pest in the early 2000s. In 2007, Asian Honey Bees (A. cerana) were first detected in Cairns; attempts to eradicate this successful colonist failed, and a containment program is now in effect. Asian Honey Bees are common carriers of a second species of mite, Varroa jacosoni, which cannot normally reproduce amongst European Honey Bees. In 2015, a swarm of Asian Honey Bees infected with V. jacobsoni were destroyed at the Port of Brisbane; subsequently, another colony was located at the port. In July 2016, infected bees were detected amongst a colony at the Port of Townsville, and a month later another infestation was found in the backyard of a house at Annandale, a suburb of Townsville.
Although traditionally associated with the Asian Honey Bee, V. jacobsoni nevertheless poses a real danger, as it has proved capable of ‘host shifting’ within a relatively short period of time if exposed to European Honey Bees. In 2008, two separate lineages of V. jacobsoni were found to be reproducing in both drome and worker bee brood of A. mellifera in New Guinea. With an established feral population of A. cerana already present in Australia, and continued instances of the inadvertent introduction of bees infected with A. jacobsoni, there is a potential for the pathogen to come in contact with both feral and managed A. mellifera, and eventually adapt to this new host.
Early detection is vital for containment, and the Australian Government monitors cargo ships entering our ports for traces of bees or other pests. Plant Health Australia and Biosecurity Queensland also administer the National Sentinel Hive Program, in which ‘sentinel’ bee hives are located near ports and checked regularly for the presence of mites. The Queensland Beekeeper Mite Surveillance Project is a joint initiative involving Biosecurity Queensland and the Queensland Beekeeper’s Association, and each year bees are collected from hives throughout the state and tested for mites.
The Varroa mite is prohibited matter under the Biosecurity Act 2014, and in response to the mites detected in Townsville, Biosecurity Queensland has increased surveillance and imposed restrictions on the movement of bees, bee hives, bee products and equipment. Teams of experienced beekeepers from around Australia have been recruited to conduct field work in the Townsville area in late August and early September 2016.