By Alan Harman
Australia’s European honey bees (Apis mellifera) are at risk of breeding themselves into extinction by mating with the invading Asian honey bees (Apis cerana)
The Western Australia Farmers’ Federation says beekeepers are being warned about the risk of unnatural matings with a new study showing honey production and pollination services could be at risk due to the presence of Asian honey bees in Queensland.
The mating makes the European bees’ eggs unviable and as the Asian honeybee becomes more widespread, the inter-specific mating will increase, resulting in fewer in less worker bees.
The Australian Rural Industries Research and Development Corp (RIRDC) says Prof. Ben Oldroyd and Dr. Emily Remnant of the University of Sydney conducted the research into the impact if the two species mate after the Asian honey bee became established around Cairns in 2007.
The research found queens and drones of the two species often meet and mate as they fly at similar times and places. Genetic testing using DNA markers showed the presence of Asian honey bee sperm in the sperm storage organs of one third of the Australian commercial queens sampled in Cairns.
The mating is only one way with beekeepers saying Asian honeybee queens can die if they mate with the European honeybee drones, because they’re much larger.
In a report for the RIRDC, Oldroyd and Remnant say previous studies in Japan showed that if there are no other males to mate with, A. mellifera queens will mate with A. cerana drones.
“After such matings eggs either fail to hatch, hatch into drones, or, rarely, into female clonal offspring of the queen,” they say.
“Drones of both species fly at similar times of day, so there is opportunity for queens and drones of different species to meet and mate.”
Researchers developed DNA tests to determine if they could find A. cerana sperm in the spermathecae of A. mellifera queens and A. mellifera sperm in thespermathecae A. cerana queens.
They tested 12 A. mellifera queens from Cairns and found four had mated with one or more A. cerana males. A test of 22 A. cerana queens found none had mated with A. mellifera drones.
The researchers tested 213 eggs from three naturally mated queens in the Cairns area with their DNA test. The three queens all had A. cerana sperm in theirspermatheca, but the researchers did not detect any hybrid eggs and say this led them to assume that hybrid eggs do not hatch and are removed by nurse workers.
They also used artificial insemination to cross five A. mellifera queens with sperm collected from A. cerana drones. They tested the eggs of these queens with the DNA test.
One queen produced heterospecific eggs. One queen produced a thelytokous worker. That is, the egg fertilized itself and produced a copy of the queen’s genotype.
“Thelytoky is a potential major worry for the industry,” the report says. “In South Africa there is a thelytokous strain of honey bee called A. mellifera capensis. Workers of this strain enter production hives and parasitize them with their eggs. These workers never do any work, so the host colony quickly collapses and dies.”
Honey Bee and Pollination Program advisory committee chairman Dr. Michael Hornitzky says both commercial and hobby beekeepers are on the front line ofbiosecurity and need to be aware of possible threats to bees, such as interspecies mating, as well as best practise management and control methods.
“Australia’s European honey bee colonies will become increasingly at risk of collapse if mating with Asian honey bees becomes a regular occurrence,” Hornitzkysays.
“Depending on the proportion of Asian and European honey bee males that mate with the queen, her fertility will be reduced and her eggs will not hatch, reducing the productivity of colonies headed by European honey bee queens that mate in areas where Asian honey bees are present.”
Hornitzky says this is in turn could lead to bees being less effective at honey production and pollination.
“We know that in Australia approximately 65% of horticulture and agricultural crops produced require pollination services from honey bees, so this is a key concern, especially as it will impact feral bee colonies as well as managed hives,” he says.
“This important research serves as a warning to beekeepers that it’s better to source queens only from areas where Asian honey bees are not present.
“We should do everything we can do to stop the spread of Asian honey bees south into Australia’s major queen breeding areas,” Hornitzky says.
Australian Honeybee Industry Council executive director Trevor Weatherhead says the industry expected inter-specific breeding and the council wants the Queensland government to set up a control area in the north of the state to protect domestic and international bee markets.
“We’ve been proposing that we have either a control area or biosecurity zone … so that bees in that northern area wouldn’t be able to come south without a permit,” he tells the Australian Broadcasting Corp.
Cairns beekeeper Maurie Damon’s bees were involved in the research, tells the broadcaster the findings are concerning but not critical.
He hasn’t noticed any major impact and the queens, who mate with multiple drones, are still productive enough, and the reject eggs become a food source.
“The workers… pick up immediately that the eggs that are hybrids… are not right… so they (eat) them as a protein source,” he says.
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