Scientists have recommended limits on urban beekeeping after a peer-reviewed study found introduced honeybees could be harming Australian native bees and risked driving them to extinction.
The Australian research, published in Frontiers in Bee Science, found native bees living in areas with high densities of introduced honeybees had fewer female offspring and a higher death rate in their first year of life.
Dr Kit Prendergast, the lead author of the study, said honeybees posed a threat to the health and size of native bee populations – and there was a risk population declines could eventually lead to local extinctions.
“By boosting honeybee numbers, you can be harming native bees,” said Prendergast, a native bee scientist and conservationist at the University of Southern Queensland.
More than 1,700 species of native bees have been identified in Australia, and they play an important role in pollinating native trees and wildflowers. Unlike the common domestic honeybee, which was introduced to Australia from Europe about 200 years ago for honey and crop pollination, most Australian native bee species aren’t yellow and black and don’t live in hives.
Native bees ranged from some of the smallest bees in the world to “really big, bombastic ones” like the Dawson’s burrowing bee, a ground-nesting bee with a 4.5cm wingspan, Prendergast said.
Over two spring-summer seasons, Prendergast and a team of researchers studied native bees living in specially designed bee hotels – wooden boxes designed for native bees to rest and breed in – across 14 sites in Perth, investigating whether proximity to European honeybees impacted various signs of health in native populations.
Both introduced and native bees needed nectar and pollen to survive and reproduce, but when resources were scarce – particularly during drought or after bushfires – introduced bees dominated, as they could travel further and forage on a greater variety of plants.
As a precautionary step, the authors recommended limits on urban beekeeping, and steps to prevent and control swarming – where the queen takes half the colony to find a new place to live – and feral hives, especially in state and national parks.
Protecting and increasing flowering trees like eucalyptus, myrtles and bottlebrushes and wildflowers could help support native bee populations, the authors said.
Dr Katja Hogendoorn, an expert in native and introduced bees at the University of Adelaide who was not involved in the study, said while European bees played an important role in crop pollination, their use for honey production should be limited to protect native species.
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She said the findings were consistent with other research showing high densities of honeybees reduced available nectar and pollen resources for native populations, and larger bees in particular struggled to find enough food to fly.
Compared to other countries, Australia had “an enormous number of feral hives” – or honeybee colonies in the wild – she said, but as they were often high up in eucalyptus tree hollows, it made removing them extremely difficult and labour intensive.
Hogendoorn said protecting and planting flowering native plants was critical, given bees suffered from the effects of habitat loss, climate change and competition from honeybees.
Hogendoorn said about a third of Australia’s bee species were yet to be described. She was part of a team that described 71 new native species of resin pot bees, which are unique to Australia and build nests out of resin.
It was important to understand what species there were, where they lived and whether they were endangered, she said.
“We still have a lot to discover,” she said. “We may be losing species that we don’t even know about yet.”
