An ant cake
My 2021 entry for the threatened species bake-off, theme “ecosystem engineers” #TSbakeoff. The annual baking competition is held just prior to Threatened Species Day on September 7th.
This is the Sugar Ant (Camponotus sp. nr. terebrans) emerging from its sandy nest at the base of a tree. On the tree, also at the entrance to the nest, are the eggs of the Arid Bronze Azure butterfly (Ogyris subterrestris petrina). The older, hatched eggs are pale in color, whilst the new eggs are much darker. This butterfly is critically endangered in Australia and is totally reliant on the Sugar Ant to rear the caterpillars. Once the eggs hatch, the ants carry the larvae deep into the nest. We’re not completely sure what happens next, but it is possibly something like this:
Butterfly larva produces amazing-smelling pheromone which convinces the ant to look after it like a queen. But butterfly larva is secretly eating the ant babies so it can grow big and strong. Ants are completely fooled by the sweet-smelling, but diabolical caterpillar and look after it until it emerges from the ant nest as a beautiful butterfly. (1)
Inspiration for this cake actually came from this photograph of our Sugar Ant with the eggs of the eastern Arid Bronze Azure butterfly (Ogyris subterrestris subterrestris).
You might remember earlier this year I was horrified to discover that “our” butterfly was 7th on a list of 26 Australian butterflies most likely to go extinct in the next 20 years (2). I put out a call for any scientists willing to share their knowledge to help us better protect our significant butterfly population.
One of those to respond was Prof. Alan Anderson. Yep, the ant-man and Fellow of the Australian Academy of Science; so much excited squealing when I received that email.
Hatched eggs of of the Arid Bronze Azure butterfly. The larvae eat their way out through the central dimple. The eggs with holes in the side have possibly been parasitised.
A worker ant of Camponotus sp. nr. terebrans The “sp. nr.” in the scientific name means “species near”, ie it is similar to, but distinct from the described species of Camponotus terebrans.
I was wondering whether the attendant Sugar Ant for our butterfly is the “true” Camponotus terebrans (which is pretty common and widespread), or perhaps it is a rarer ant from the terebrans species complex. I collected some ants from a nest at the base of a tree where there were also many butterfly eggs (It was a Blackbox Eucalyptus largiflorens for those who like the details). I sent the ants to Prof. Anderson and the response came: “The ant species is indeed a member of the C. terebrans complex, but not the large-eyed species. There are many species in the complex, all going under ‘’terebrans’’. I have a dozen or so sorted, and have genetic data on six of them. Your species doesn’t match anything I have.”
Wow! Hoping that some DNA barcoding of our ants can be undertaken to better understand their identity. I’ll keep you posted.
And one last cool thing about the Sugar Ant. We call them Piss Ants because it is not uncommon to see them clustering together to feed where a kangaroo has urinated. Turns out that Piss Ant is the correct name.
Scientists on Kangaroo Island proved that Camponotus terebrans prefer urine over sugar water. They return to forage on dried urine patches for weeks, mining the urea. Australian soils are typically nutrient-poor, so urine is one way for the ants to get their vitamins and minerals, especially nitrogen for protein (3).
And if you’re wondering how the cake was made: it’s just a basic butter cake with butter frosting for the tree, and raw sugar for the sand. The ant and eggs are made from fondant, with the legs and antennae crafted from copper wire. I painted the fondant with food dye. I’ve called it “lockdown fondant”. I had to do some substitutions because shopping for fondant ingredients is not one of the five reasons I can leave home at the moment (Covid lockdown #7 for us). I used this Thermomix fondant recipe but used brown rice syrup instead of liquid glucose and light olive oil instead of glycerine.
More information:
You can see all the threatened species bake-off entries here https://www.facebook.com/TSCommissioner
A flashback to last year: I made a butterfly cake https://www.malleeconservation.com.au/blog/ogyris-bakeoff
A more scientific and detailed exploration of the ant-butterfly relationship for Ogyris subterrestris subterrestris can be found here https://sabutterflies.org.au/lyca/subterrestris.html
More on the list of threatened butterflies here https://www.malleeconservation.com.au/blog/ogyris
Petit et al. (2019) Camponotus ants mine sand for vertebrate urine to extract nitrogen. https://onlinelibrary.wiley.com/doi/full/10.1111/aec.12840
The Arid Bronze Azure butterfly Ogyris subterrestris subterrestris