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Could flies be the back-up species to pollinate crops in place of bees?

ABC NEWS 2/07/2022

Native flies are "accidental" pollinators, and in some instances stay on flowers longer than bees. (Supplied: DPIRD)

Researchers in Western Australia have confirmed a blowfly species to be as good at pollinating as bees.

Since the Varroa mite outbreak in New South Wales, the threat of losing bee populations has become even more significant for beekeepers and farmers alike.

Scientists from the Department of Primary Industries and Regional Development (DPIRD) have been undertaking this research since 2019 as part of a national project funded by Hort Innovation.

The premise of the trials was that the industry was worried that it was solely reliant on one species of pollinator — bees — according to DPIRD senior entomologist David Cook.

'Accidental' pollinators

Mr Cook says because blowflies have hairy legs, they pick up pollen almost by accident.

"They go from flower to flower all day because they're a big insect and it takes a lot of energy to constantly fly around," he said.

In some instances, native flies were found to have stayed on a flower for an average of 30 seconds, transferring pollen between flowers.

Blowflies can operate at slightly lower temperatures to bees, which is an additional benefit of this insect as a pollinator, particularly in colder avocado-growing regions like southern Western Australia and Tasmania.

The other benefit of blowflies is they don't sting you like bees do, so managing them can be — quite literally — less painful.

Of course, blowflies don't have the added advantage of the sweet by-product that bees make — honey — which presents a challenge of making fly pollinators economically viable.

Containing the flies

A major advantage of having bees as pollinators is that they live in hives, so they can be fairly easily controlled and moved around if need be.

This is one of the greatest challenges with the commercialisation of blowflies as managed pollinators in crops and orchards.

However, researchers have found the size of the fly can be bio-engineered to be smaller than usual, to prevent them from flying too far away from a crop.

Adult flies can also be sterilised to prevent them from breeding or becoming overpopulated.

"The flies we're using are not the sort that are going to be pests to humans or livestock," Mr Cook said.

"We can also deploy lures that release an odour that flies like — one [humans] can't detect."

Flies are able to detect decomposing protein from 1-1.5 kilometres away.

This means the released odour can not only help to retain flies within an orchard, but also attracts nearby flies from native vegetation.