Witchetty grub wonder

PhD candidate Conrad Bilney is using DNA barcoding to identify our most iconic edible insect

By Dr Giselle Roberts

PhD candidate Conrad Bilney has over two thousand photographs documenting his scientific quest to categorise our most iconic edible insect, the witchetty grub.

Sitting in his office at La Trobe’s Albury-Wodonga campus, I am given the highlights from Bilney’s five field trips to Central Australia. “Here we have Aboriginal Traditional Owners digging for grubs,” he explains, clicking the mouse to the next image of a red-orange landscape punctuated by trees and tracks. Next, cuppa time at base camp. A purple-dappled sunset transforming into a star-speckled night. And a plump little witchetty grub climbing purposefully across an outstretched hand.

Mr Bilney, of Kokatha-Wirangu descent from the Nullarbor Plain region of South Australia, is using DNA barcoding to identify different edible insect species. His project is also about the people, places and self-discoveries along the way.

GISELLE ROBERTS: Conrad, I thought there was just one type of witchetty grub. You have dispelled that very quickly by showing me dozens of different specimens, many of which look nothing like the iconic grub. So, what exactly is a witchetty grub?

CONRAD BILNEY: Basically they are edible insect larvae found in a range of different host trees. Witchetty is, in fact, not the insect but the hooked stick that Aboriginal people push into the ground to pull out the grub. It looks as if the stick got confused with the insect, the explanation was lost in translation, and the name has stuck. Some Aboriginal people call them bardi grubs, and maku is another more generic word for a bug that lives in a tree. Many just call them witchetty grubs.

GR: And you are classifying them, for the very first time.

CB: The witchetty grub is the only edible insect classified in Australia, but after talking with Aboriginal people who are experts in plants and animals, they told me there were more than 20. I started out this project trying to find as many bugs as possible. I ended up with 301 specimens. After collecting them, I brought them back to the lab and used DNA barcoding to identify them. We found 23 insect species that are either moths, beetles or caterpillars. They come in different shapes, colours and sizes, but they’re all considered to be witchetty grubs because their larvae looks the same.

GR: Where do you find them?

CB: You can pull up a log or tree root and find three or four in a row. One tree in Kiwirrkurra, out in the Gibson Desert, contained 20 witchetty grubs. When travelling cross-country, Aboriginal people will often break off a root, put it under their arm, and leave the grubs in the root until they are ready to eat them. No need for refrigeration. The grubs are fat, packed with nutrients, and can survive up to three weeks just like that. I once bought a log back from Western Victoria and left it under my desk. Big mistake. Weeks later I heard this rustling sound and out came a moth!

GR: How easy are they to collect?

CB: We worked closely with Traditional Owners to collect the grubs. Their knowledge was amazing, astonishing. One time we were talking about particular varieties of trees and one of the Traditional Owners in the car told me about a clump of them, 200 kilometres away, out on a stock route, that were full of grubs. Some Aboriginal people can identify the presence of grubs based on whether a tree is dying or stressed. We had about a 95% strike rate. And while we were always able to find grubs, there were times when I had trouble getting them back to the lab. “You’re not putting that in a jar and taking it back to the university? That looks too yummy not to eat,” community members would say. They see them as food, not as something to sit on a lab bench, and sometimes I would come back with half a grub.

GR: What do they taste like?

CB: Something like scrambled eggs. You can cook them in ashes or in a frying pan and they taste like eggs with a hint of mocha left in the palate. Three of them fill me up, because the protein content is very high.

GR: Tell me about the highlights of this project so far.

CB: It’s hard to pick a highlight. It’s all been good. I particularly liked being a part of two BushBlitz expeditions, involving specialist taxonomists, Traditional Owners, Aboriginal communities, rangers and landowners, teachers and students. One scientist from Western Australia was looking for snails. He found a new species. It was great to work as part of a team and to be part of that research discussion. As far as I know, no one is doing DNA barcoding on edible grubs in Australia, and I was the only scientist on the expedition who was Aboriginal. I was chuffed.

GR: It’s inspiring, all of it.

CB: After a day looking for grubs I would sit down at camp, in the desert, with a beautiful wind blowing and think, “Does life get any better than this?” I have been inspired ever since. And this research, this knowledge I am building, just gets better and better. I am overawed by it.