Wanted: Photos of flies feeding on frogs (for frog conservation)

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UNSW Science and the Australian Museum want your photos of frogs, especially those bitten by flies, for a new (and inventive) technique to detect and protect our endangered frog species.

You might not guess it, but biting flies – such as gnats and mosquitoes – are great tools for science. The blood “taken” by these parasites contains valuable genetic data about the animals they feed on (like frogs), but first researchers need to know which parasitic flies bite which frogs. And that’s why they need you to submit your photos.

“Rare frogs can be very difficult to find on traditional scientific expeditions,” says PhD student Timothy Cutajar, who leads the project. “Rare or cryptic species [inconspicuous] can be easily missed, so it turns out that the best way to detect some species might be through their parasites.

The technique is called ‘iDNA’, short for invertebrate-derived DNA, and researchers Mr Cutajar and Dr Jodi Rowley from UNSW Science and the Australian Museum were the first to harness its potential to detect species cryptic or endangered frogs.

The team first deployed the technique in 2018 by capturing frog-biting flies in habitats shared with frogs. Kind of like Michael Crichton’s premise jurassic parkwhere DNA from past blood meals is contained in the bellies of flies, Cutajar was able to extract the collected blood (and therefore DNA) and identify the species of amphibian on which the flies had recently fed.

Light traps for catching frog-biting midges in Chichester State Forest. Photo: Tim Cutajar/Australian Museum

These early trials revealed the presence of rare frogs that traditional search methods had missed.

“iDNA has the potential to become a standard technique for surveying frogs,” says Cutajar. “[It could help] in the discovery of new species or even the rediscovery of species that were believed to be extinct, I therefore wish to continue to develop techniques for investigating frog DNA i. However, there is still so much we don’t yet know about how frogs and flies interact. »

In a bid to understand the varieties of parasites that feed on frogs — so Cutajar and his colleagues can attract and catch the most informative and prolific species — the team is reaching out to the public for their frog photos. .

“If you have photographed frogs in Australia, I would like you to examine your photos carefully, looking for frogs that have flies, gnats or mosquitoes sitting on them. If you find flies, gnats or mosquitoes in direct contact with frogs in one of your photos, please share them.

Tree frog bitten by flies.jpg

Submitted photos will be analyzed for the frog and parasite species they contain, helping to inform future iDNA research. Mountain Stream Tree Frog (Litoria barringtonensis) bitten by Sycorax. Photo: Tim Cutajar/Australian Museum

“We will comb through the photographs of frogs submitted as part of our investigation,” says Cutajar, “focusing on the characteristics that make a frog species a likely target for frog-biting flies.

“It is unlikely that all frogs are equally parasitized. Some frogs have natural insect repellents, while others can repel flies. Flies themselves can be fussy about the types of sounds that attract them and are probably not uniformly abundant everywhere.

Already, the new iDNA technique, championed in herpetology by Mr. Cutajar, has shown great promise, and by refining its methodology with data submitted by the public – citizen scientists – our understanding of the ecology and biodiversity of frogs can be further enlarged.

“The power of collective action can be incredible for science,” says Cutajar, “and with your help, we can usher in a new era of improved detection, and therefore conservation, of our incredible amphibian diversity.” .

Read more: Frogs are dying again in droves, and we need your help to find out why

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