By safeguarding horticulture's littlest workers, this tropical fruit farmer is planning ahead for the arrival of a potentially devastating biosecurity risk.

The mite doesn't pose a direct threat to native bees, but there are indirect threats to native bees through the spreading of viruses.

They're some of horticulture's smallest workers, but without pollinators, most crops simply wouldn't exist. Bees, both European honey and native, are vital to pollinating flowers, but they're facing challenges that could lead to devastation for the fruit and vegetable industry. To avoid potential catastrophe, a tropical fruit farmer in central Queensland is working to safeguard native bees on his farm.

On 22 June 2022, a tiny pest the size of a sesame seed was found at the port of Newcastle, sending Australia's honey bee industry into chaos.

Varroa mite has been described by the federal government as 'one of the greatest threats to Australia's honey and honeybee pollination plant industry,' and after 15 months of eradication efforts and around 14,000 beehives burnt, the National Management Group (NMG) moved the response from eradication to management. For more information on the outbreak, check out the Australian Government's rundown.

Dr Tim Heard is an entomologist who had a career with the CSIRO and now runs Sugarbag Bees. He said varroa mite will have a big impact on the honey bee industry, particularly in the cost of production. However, he said the spread of the mite in other parts of the world shows us that the industry will survive and continue to grow.

While it isn't a death sentence to the honey bee industry, he said the arrival of varroa mite will have a huge impact on Australia's wild pollinators, particularly feral honey bees.

'They [wild honey bees] will almost all die of varroa mite attack. So we've got this situation where there will be fewer honey bees in Australia,' Dr Heard says.

While varroa mite was initially picked up in New South Wales, Dr Heard also says it's inevitable that it'll spread. But he hopes it will be a few years before it makes it to some of the furthest parts of the country.

'It's [varroa mite] a very good disperser, it's a real survivor. Honey bees are everywhere, and it [varroa mite] can jump from hive to hive.'

The mites are tiny external parasites that feed on honey bees as well as transmit viruses that cause malformation and the weakening of honey bees.

The mite doesn't pose a direct threat to native bees, but there are indirect threats to native bees through the spreading of viruses. Dr Heard said if a mite carries a virus from a honey bee hive, the virus particles can be spread on flowers, and if native bees visit those flowers, they can catch the virus. While there is a risk, the scale of damage will be next to impossible to measure.

Despite this, there's also a potential benefit to native bees, as they may find reduced competition for forages when the population of feral honey bees declines.

Challenge

The arrival of varroa is devastating for the honey industry, but it's not the only thing that will suffer. Dr Heard said the loss of feral honey bees does create a great risk to horticultural industries that rely on feral bees as one of a number of pollinators in the wild.

Varroa mite isn't the only risk faced by pollinators in Australia, however. Australia has over a thousand native bee species, most being significantly smaller than European honey bees or bumblebees. They live primarily in the hollows of trees, branches and in burrows in the ground.

Like many other native species in Australia, they're at risk of population decline due to habitat loss from both development and natural disasters, such as bushfires.

David Groves is a tropical fruit farmer based in central Queensland, where he and his parents, Ian and Sandi, grow mangoes, lychees, avocados, carambolas and more.

'Friends with farms in the fire scar noted that overnight all the pollinators vanished,' David says.

On the farm, the family has always had pollination from wild sources, with around a third of the farm being bushland, and habitat for pollinators.

Around four years ago, approximately 400 hectares of neighbouring land was sold off and cleared for development, and not long after the Black Summer (2019-2020) bushfires spread through bush and farmland across the coast.

'Friends with farms in the fire scar noted that overnight all the pollinators vanished,' David said. 'It killed all the hives with the heat, any hollow trees and hollow logs burnt. And that scared me.'

He noticed pollinators in the region disappearing and decided it was time to do something about it and to try to safeguard them for the future.

Solution

To protect pollinator populations, David decided to research native beekeeping, reducing the risk of varroa mite impacting pollination.

To protect pollinator populations, David decided to research native beekeeping, reducing the risk of varroa mite impacting pollination and building up populations of the species already native and present in the area. The two stingless species he keeps are Austroplebeia Australis and Tetragonula hockingsi.

'I'm not interested in keeping honeybees, I don't like being stung,' he says.

'If you want to make honey, [honey bees] are the way to go, but I want pollination. Native bees seemed like a better way to go for our purposes.'

After reading that a hectare of bushland can support at least one hive, David decided to aim for a long-term goal of setting up around 200 hives for the property.

Native bees have a small flight radius, travelling only up to about 500 metres from the hive, considerably less than the 6 kilometres honey bees can travel. David says that has both its pros and cons; it does mean you have better control of pollination zones, but for larger farms, you can't have only a single site of beehives on-farm.

Supplies to start keeping native bees are easily accessible in Australia. David bought his first two hives full of bees online, which were mailed out to him. David says he got a lot of his knowledge through the 'native bee bible,' called The Australian Native Bee Book by Dr Tim Heard, but there's also plenty of information about bees online.

To build up the populations through the number of hives, David uses three methods. He splits pre-existing hives, rescues hives from places they won't survive, like fallen trees or burn piles, and has an 'eduction' system for wild hives.

David splits pre-existing hives, rescues hives from places they won't survive, like fallen trees or burn piles, and has an 'eduction' system for wild hives.

To split hives, David has built new hives from hardwood harvested from trees that have fallen on the farm during a cyclone, but says they can be bought pre-made, or made using any timber, such as pine or cypress. The standard design for hives is to be made from layers stacked on top of each other. To replicate a hive, when each layer of a box is filled, the layers are taken apart and attached to a new, empty segment. The bees then explore and expand into the new half of the hive.

Unlike a honeybee hive, native bees have multiple queen cells on the go at all times, and 'princess bees' emerge semi-regularly, meaning splitting native hives has a high success rate.

He has also relocated hives from fallen trees and burn piles, even from fruit trees being cut down. Neighbouring landowners have also learnt about David's passion for native bees and will call him if they find a hive in a place that won't survive. To relocate them, as much of the brood and eggs are removed from their original home and into a new hive, moving as many bees into the box and safely relocating the box. Those who move native bees professionally sometimes have a small vacuum, which can safely remove the bees and move them to a new home.

David's also found around 15 colonies living in the wild on the farm. He has no plans to move them, only to keep them safe and potentially propagate more hives from the bushland. To do this is called 'eduction', or budding, where he adds an empty box to the outside of an existing hive. The bees can still exit from the tree hollow through the new box and have the option to start a new colony in it.

This method can work, but it's considerably slower than splitting hives manually. Out of the 15 attempts he has made at budding over three years, he's only had six hives take hold, compared to the success of splitting pre-existing hives every 12 to 18 months.

Where he keeps the hives once they have split is also important. Native bees aren't as good at regulating their hive temperature as honeybees.

'They don't carry water back to the hive to cool it, and they're not as good at keeping it warm in winter,' David says. For those reasons, it's essential to find a spot that gets enough sunlight in winter but not too much during summer.

Beyond actively setting up and building hives, David and everyone on the farm at Groves Grown Tropical Fruit do their part in creating a pollinator-friendly environment. David and his mum, Sandi, plant a lot of flowering trees and shrubs for windbreaks and green breaks, as well as annual flowers on the ends of rows of trees so pollinators have flowers to forage on during the off-season of tropical fruit flowering.

Outcome

David now has around 26 boxes of bees, which live in groups, on his verandah and under covers such as at irrigation pump sites around the farm.

David now has around 26 boxes of bees, which live in groups, on his verandah and under covers such as at irrigation pump sites around the farm.

A lot of the outcomes are not measurable; having never experienced the farm without any pollinators, it's impossible to know what difference reduced bees in the area would mean for fruitset.

'It might just mean the difference between an average crop and a good or big one. But at this stage, we haven't had that experiment happen to us, and I don't intend to let it happen.'

However, David now feels far more confident in the future, knowing that even if uncontrollable events occur - like the loss of habitat on neighbouring land due to clearing, fires or the encroachment of varroa mite - he has a safe population of native bees.

The risk of bushfires is not unknown to the Groves family. In 2019, bushfires spread to bushland bordering the farm, but fortunately, no fruit trees were impacted. If bushfires do again move towards the farm, David can have the hives closed up and taken somewhere safe until the danger has passed. Similarly, should there be any risk of bee baiting for varroa mite on public or neighbouring land, the hives can be kept far enough away from danger that they shouldn't be impacted.

David now feels far more confident in the future, knowing that even if uncontrollable events occur, he has a safe population of native bees in hives.

He's still a long way away from his goal of 200 hives on the property. But should he reach that goal and want to continue propagating the hives, he has plans to foster them in friends' backyards.

'Towns and cities are amazing places to keep native bees because there's a real severe lack of hollow trees and suitable nesting sites and an overabundance of irrigated flowers year-round,' David said.

He hopes to have bee boxes spend most of the year living in suburbs with flowers and gardens to forage on, with the potential to be transported back to the farm during peak pollination season, further safeguarding native bee populations.

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