The third and final dung beetle species imported to Australia as part of the Dung Beetle Ecosystem Engineer (DBEE) project is finally here, currently spending their time in climate controlled chambers at Charles Sturt University in Wagga Wagga.
The Moroccan species, Gymnopleurus sturmi, were expected to arrive in 2021 but have had to remain in the CSIRO's lab in France when COVID-19 restricted movement for the six legged workers.
CSIRO project lead Dr Valerie Caron said the new arrivals are distinctly different to the current two imported species in Australia, also brought in through the DBEE project.
"The first two species [O. vacca and O. andalusicus] are tunnellers, which burrow dung straight into the ground to house eggs and feed larva," she said.
"G. sturmi is a roller, which takes a chunk of dung, shapes it into a ball and rolls it away to bury it."
While both of these behaviours reduce surface dung, the two different types of beetles working in synergy speed up the process. Tunnellers focus on the middle of a cow pat; rollers take dung from the sides," Dr Caron said.
"Working together, both types of beetles disperse dung more quickly, deterring flies from laying eggs...and because G. sturmi aggregate on the surface in search of a partner, they trample the pat, too. This should further deter flies."
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Although the latest arrivals move dung in a different way to the other two species, the benefits of all dung beetles are very similar.
Through the act of burying dung, dung beetles can improve the flow of water, nutrients and carbon into root zones, enhancing soil carbon and fertility as well as boosting pasture productivity.
Their actions also help promote a healthier grazing environment by controlling livestock parasites like gut worms.
Affected livestock produce dung packed full of worm eggs, and the larvae that hatch from the eggs remain on pasture plants, soon to be consumed by livestock which then become infected. Active, rapidly-colonising dung beetles can make fast work of worm-ridden waste.
"Interestingly, dung beetles are 'specialists in their field', with no single species active in all regions across all seasons," Dr Caron said.
Despite the establishment of 23 introduced species since the 1960s, there aren't many in southern Australia which remain active in late winter and/or spring.
The DBEE project aims to fill that gap, complementing established species to give graziers year-round dung beetle activity.
At home in Morocco, G. sturmi beetles are typically active in spring and even into summer. This means that once they're out and about on Australian soils, the G. sturmi's benefits will be particularly noticeable around that time of high activity.
Charles Sturt University will lead a mass-rearing program for this newly-imported dung beetles species with the help of Australian producers through the DBEE project.
"Eventually, G. sturmi will be placed into outside cages to protect them against predators such as ibis, crows and foxes," Dr Caron said.
"The producers [involved in the DBEE project] will feed them for a year or more, and all going to plan, we'll have sufficient numbers to release this new species in the field in spring 2023."
