Parasitoid Wasp (Labena grallator) Ovipositing

Recorded at the Smithsonian Environmental Research Center, Edgewater, MD, USA on July 18th 2017.

Here you can see a parasitoid Ichneumon wasp (Labena grallator) searching for a prey living inside a dead branch. She uses her antennae to locate the prey and sets out to drill with her ovipositor straight into the wood. She does a few exploratory oviposition exercise before committing to a full injection. At multiple instances the wasp is chased away by ants. Indeed, in the last sequence the oviposition is interrupted halfway by an ant climbing onto the wing of the wasp and forces her to leave.

The drilling process is quite an epic undertaking involving secretion of enzymes digesting lignin and cellulose. The world record breaking longest ovipositor of another ichneumon wasp species the Giant Ichneumon Wasp (Megarhyssa macrurus) is rather notorious.

The natural history of the parasitoid wasps is not limited to their impressive egg-laying organs. Most parasitoid wasps inject curious chemical particles inside their caterpillar prey together with their eggs. These particles suppress the immune system of their victims allowing the eggs to develop without any defensive reaction. Research has shown that the particles have evolved from nudiviruses that infect ovaries of many insect species. At around 100 million years ago, DNA viruses that inserted themselves into wasp genomes have lost their ability to replicate. Their proteins used to package infectious viral particles have evolved into a delivery system coating the immune suppressants. This fascinating evolutionary key innovation lead to the speciation of the parasitoid wasps who have diverged to adapt parasitising many different insect prey.

 

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