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.
3 Comments
i’m in the state of rhode island, and noticed one of those giant lchneumon on my car. since iv’e never seen one before it scared me, because i didn’t know if it would sting me or not so i blew it away from me…
Fear not John! These wasps are harmless since their ovipositors evolved for egg laying not for stinging. Aren’t they fascinating? If you haven’t already did so, check out the longest ovipositor ever in our world here: http://naturedocumentaries.org/3843/giant-ichneumon-megarhyssa-macrurus-ovipositing/
Megaryhssa macrurus have long ovipositors, but it’s definitely not true that they hold any sort of world record. Its ovipositor is up to about 3.5 inches long, but even the sympatric M. atrata can surpass that at about 4.3 inches. That of the neotropical Dolichomitus longicauda can reach up to 6.5 inches, and I wouldn’t even put stock in that being the longest worldwide without actually comparing measurements between other Rhyssinae, Ephialtini, and even a few out-group species with longer than typical ovipositors for their subfamilies.