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Parasitoid wasps, poisonous butterflies and Grevillia Gorge


Kerry Mazzotti

I bumped along the dusty dirt road out of base camp with Dr Erinn Fagan-Jefferies from Adelaide University, Dr Rod Eastwood from the Western Australian Museum and a few other bug enthusiasts.

Dr Erinn Fagan-Jefferies was already a favourite of the students in my class. Erinn has engaging videos raising awareness of the tiny wasps she studies. These wasps are called parasitoid wasps because they lay their eggs in caterpillars and when the baby wasps hatch they eat the caterpillar from the inside out!

Dr Rod Eastwood is an expert on butterflies and has spent a lifetime gaining and sharing knowledge of butterflies from Australia and across the world.

We stopped at our first site and I learned quickly how we would find the butterflies and wasps that inhabited the site. The main technique that I helped with was ‘sweeping’ – taking a butterfly net and sweeping it through vegetation to check what we caught. It was incredible to see the diversity of invertebrates caught in a single sweep. Once caught, specimens of interest were preserved to take back to base camp. I collected three specimens of interest, first a fly, then a native bee and finally – a parasitoid wasp! I excitedly presented my specimen tube to Dr Erinn for safe-keeping before we left the site.

I shadowed Dr Rod as he expertly observed butterflies and decided which ones to catch. After a fair bit of practice, I caught my first butterfly. I was surprised and excited to hear that it was the first specimen of that species that had been caught and that Dr Rod would like to take back to the WA Museum to retain in their collection!

Dr Rod told me all about the butterfly I had collected. It’s called a Common Crow, which doesn’t sound very remarkable, I much prefer the scientific name Euploea corinna (Nymphalidae). This butterfly feeds on poisonous plants, which in turn, makes the butterfly poisonous to predators. The butterfly displays this poisonous trait to potential predators through its vibrant patterns, reminding predators not to eat it. This survival strategy is called Aposematism. The poison isn’t enough to kill the predator, just a little reminder that they taste bad and make them feel sick, so they are not eaten again.

Dr Rod explained that the caterpillars of this species are poisonous as well. The only time the butterfly is at risk of predation in its lifecycle is at the egg stage. However, the male butterfly has developed an incredible strategy to protect his offspring at the egg stage as well. The male will harvest the poison from a plant and then deposit it on the female wasp where she lays her eggs. When the eggs are laid, they have a protective poisonous coating that prevents predation. These beautiful butterflies have a remarkable survival strategy that relies on poisoning potential predators from the eggs stage right through to adults.

It is such a treat to wander the wilderness with experts in their field, unveiling the secret lives of mini-beasts and the astonishing strategies they have developed to survive.

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