As Australia Day approaches, it’s appropriate to take a minute or two to reflect on our continent’s superfluous, yet often overlooked resources.
Australia’s mostly sunny climate and sprawling, crystalline beaches will probably spring to mind first. It’s unlikely, however, that you’ll be struck by how fortunate we are when it comes to the fuzzy, six-legged workers of our society — honeybees (Apis mellifera).
Unlike just about everywhere else, diseases minimally impact our honeybee populations. Given that honeybees pollinate one-sixth of all flowering plants worldwide and one-third of everything we consume, we have a lot to be thankful for.
The dearth of honeybee disease in Australia makes our continent the ideal setting for honeybee research. Think of it as the perfect experimental control for studying common honeybee diseases, some of which have devastated vast regions of countries. In the Maoxian region of China’s Sichuan Province, for example, farmers pollinate entire apple orchards by hands!
Australia’s comparably favourable setting for honeybees is in part what inspired Dr Ryan Dosselli, Research Associate at the Centre for Integrative Bee Research (CIBER), University of Western Australia, to conduct his honeybee research here in Western Australia.
Honeybee Dysentery and SmartRiders
One of the less noxious but widely spread diseases affecting honeybees is the highly contagious fungal parasite, Nosema apis. It inhabits the gut cells of honeybees and results in dysentery.
Dr Dosselli and fellow UWA researchers recently investigated the impact of N.apis on the ability of honeybees to pollinate crops. This involved attaching minuscule computer tags to 200 honeybee workers from three colonies.
These tags are akin to SmartRider or myki cards; they’re activated each time a “tagged” honeybee passes a given point.
In his study, Dr Dosselli fed sugar water to 100 newly hatched worker bees. Another 100 less fortunate worker bees were fed sugar water containing N.apis spores.
The honeybees’ time outside the hive was then tracked using the tags.
Dr Dosselli expected the infected honeybees to be less active because flying is energetically demanding. However, he hadn’t anticipated just how quickly N.apis would result in shortened flights beyond the hives. After only two days of infection, flights were significantly curtailed.
This surprising result is concerning for three reasons. Firstly, N.apis is considered to be one of the less aggressive honeybee diseases. Secondly, it’s highly contagious. Thirdly, although it doesn’t kill honeybees, it can in the context of additional stress factors.
“Problems occur if something else comes along,” explains Dr Dosselli. “It’s like us having both measles and chicken pox, and then moving to a heavily polluted area.”
Ultimately, the potential for reduced foraging range as a result of shortened flight times could detrimentally affect honeybee pollination of key agricultural crops.
Disease Tolerant Honeybees
Another interesting finding from Dr Dosselli’s study was that both infected and uninfected workers from one particular colony undertook longer flights compared with workers from the other two colonies. Additionally, the infected workers of this colony exhibited an immune response that was absent in the others.
This latter finding suggests genetic differences among the colonies and has inspired Dr Dosselli to explore whether these genetic differences can be exploited to breed disease tolerant honeybees.
A major hurdle is that selecting for a specific genetic trait frequently results in the loss or exaggeration of another.
“For example,” notes Dr Dosselli, “[genetically modified] honeybees may be tolerant to the disease but may end up being too aggressive for beekeeping.”
The undertaking is further complicated by inherent differences in different strains of honeybee diseases, including N.apis.
According to Dr Dosselli, the key will be finding a means to breed disease tolerant bees under controlled conditions.
For further information, please refer to the study at http://www.nature.com/articles/srep36649.