Some people think they're gross, but these little flies could be the key to crop security in Australia (2024)

Imagine an Australia without blueberries, avocados or apples.

They are among a third of all crops that need bees for pollination.

While northern hemisphere honey bees are increasingly threatened by disease, pesticides, habitat loss and climate change, Australian bee populations have been relatively healthy.

But the recent arrival and spread of the bee parasite varroa mite poses a threat to $14 billion of annual local agricultural production.

It's prompted governments, farmers and scientists to find pollination alternatives — and flower flies are top of that list.

Eating berries pollinated by flies

University of New England ecology professor Romina Rader is four years into a trial of fly pollinators in the Coffs Harbour berry growing region of New South Wales.

Funded by grower body Hort Innovation, scientists are comparing how managed flower flies can pollinate berry plants compared to managed honey bees.

"The first stage of the project is just to understand how efficient the flies are," Professor Rader said.

Some people think they're gross, but these little flies could be the key to crop security in Australia (1)

"The way we do that is by tagging flowers and putting bags on them while they're still in bud so that there's no pollen on them.

"Then we open the flowers, wait for the flies to visit once, twice, three times, five times, re-bag the flowers, and then wait for the fruit to develop and then weigh the fruit and compare that against the open pollinated, which is what the honey bee is pollinating."

Professor Rader said there was much that science didn't know about flies and how they could be beneficial.

"There's over 20,000 species or so in Australia, and the different families eat different things and use different habitats," she said.

"The adult stage most predominantly eats … nectar and pollen and visits flowers."

Some people think they're gross, but these little flies could be the key to crop security in Australia (2)

Agricultural research company SeedPurity, led by Cameron Spurr, breeds flies for the trials.

He said while there were many good fly pollinators, they were mainly interested in species that occurred naturally.

"It's a matter of working through identifying those that will visit the crops that have potential as a pollinator," Dr Spurr said.

Some people think they're gross, but these little flies could be the key to crop security in Australia (3)

"Then we take them through a stage of working out where they're efficient pollinators, where they carry pollen, where they visit the flowers, where they deposit pollen.

"Then once we've established that and we've got a short list of species, we actually need to be able to establish whether we can rear them if we're interested in using them as managed pollinators."

Why is this a thing?

Australia was the last continent to be free of the deadly bee parasite varroa mite until it was discovered in New South Wales in June 2022.

The disease attacks honey bee hives.

Some people think they're gross, but these little flies could be the key to crop security in Australia (4)

Thousands of hives were deliberately destroyed to stop its spread, until Australia abandoned eradication efforts and shifted to a management approach.

But it has left concerns among farmers about pollination.

Some people think they're gross, but these little flies could be the key to crop security in Australia (5)

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Brad Hocking is the lead horticulturist at the Costa berry farm at Corindi on the Coffs Coast.

"[Varroa mite] is yet to have a major impact, but we do expect that it will present greater challenges for [beekeepers] in the management of their hive health," he said.

"We are just keeping keeping close tabs on what we can do to continue to get good pollination outcomes as that proceeds."

The farm was among a few involved in the fly pollination trial, and the benefit of using flies alongside honey bees is already being noticed.

"We're just working our way towards how we might do that in a commercially applicable scale," he said.

While bees don't like to work in winter, flies do, and the idea of having pollinators year-round is very attractive.

"We're hoping to see more consistent reliable pollination through parts of the season where generally we see challenges with honey bee pollination," Mr Hocking said.

Bigger blackberries?

Blackberry grower Justin Hundley has had the flies on his farm for two seasons.

"I was a bit sceptical, like a lot of things. But I've been getting proven wrong a lot lately in farming," he said.

Some people think they're gross, but these little flies could be the key to crop security in Australia (6)

Some people think they're gross, but these little flies could be the key to crop security in Australia (7)

Flies have helped pollinate 15 per cent of his crop with an unexpected result.

"That initial fruit, the first few picks we had, there was a more sort of significant size increase from the rest of the farm just using honey bees," he said.

Aren't flies disgusting?

There's a perception that all flies carry disease and introduced species are unmanageable.

Before any commercialisation, scientists are looking at sterilising the flies before deploying them into a crop.

Some people think they're gross, but these little flies could be the key to crop security in Australia (8)

Dr Spurr said this would ensure the flies did not affect natural pollinator populations.

"They're effectively a short-term pollinator, and then they die," he said.

But is the 'ick' factor of flies pollinating food justified?

Professor Rader said it was not.

"These are flower flies, so they're [a] very charismatic species," she said.

Some people think they're gross, but these little flies could be the key to crop security in Australia (9)

"They're amazing to watch. They forage for nectar and pollen just like bees. They move through the flowers.

"They don't sting, they're hairy and they move pollen."

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Some people think they're gross, but these little flies could be the key to crop security in Australia (2024)
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