Meet Bug Lab's Queen of Venom!

Beautiful. Brain surgeon. Poisoner. Zombie-Maker. Mother. All these names can be applied to the star of Bug Lab’s venom section, the amazingly emerald-coloured jewel wasp (Ampulex compressa). If cockroaches had nightmares, she’d have a starring role. The jewel wasp’s particular piece of fiendish brilliance is her ability to deploy venom to make a cockroach do exactly what she wants and let’s just say right now that it does not end well for the cockroach. The cockroach’s ultimate fate is to end up as both a living larder and a nursery for a jewel wasp grub.

While this behaviour had been known about for many years, it took Fred Libersat and his colleagues over in Israel to crack the secret of how the jewel wasp hacked the cockroach neurosystem. In short, by stinging the cockroach in the right places, the jewel wasp’s venom can make the cockroach behave exactly as she wants.

The first sting is placed just in a bundle of nerve tissue in front of the first pair of legs. The venom causes temporary local paralysis so the normally fast-moving cockroach is stopped in its tracks. Next, stings to two parts of the brain and the cockroach starts to groom itself. After all, what mother wouldn’t want a clean nursery for her offspring? The brain surgery is performed with a stinger finer than a human hair. While the wasp can see where to put the sting to enter the cockroach’s body, she can’t see inside it, so has to find the target area of the brain by other means. She has special sensors in her stinger to let her tell differences in brain texture so she knows she’s found the right spot. In Bug Lab you can have a go at trying to sting the cockroach’s brain by feel alone.

While the cockroach is busy cleaning itself, the wasp will locate a suitable lair. She comes back to check the venom levels are still high enough by biting off part of one of the cockroach’s antennae and taking a sip of the juices.

Many wasp species sting and paralyse victims for their young, but they are usually left with the problem of hauling an unmoving and unwieldy body to where they need it. The jewel wasp has a much smarter approach. Thanks to another effect of the brain stings, the cockroach can move, but it doesn’t want to. However, a little bit of tugging from the wasp on the base of the antenna and the cockroach meekly follows like a dog on a leash.

The cockroach is led to its final resting place and the wasp lays a single egg on it. A grub hatches out and eats the still living but quite helpless cockroach in a particular way. Non-essential tissues such as the legs are targeted first – it’s not as though the cockroach needs them anymore! The vital organs are left until the end. Eating them too early would mean the cockroach would die too soon and the grub would starve. When it’s ready, the grub pupates inside the cockroach body, emerging as a wasp about a month later. The wasps themselves have more delicate tastes than their young and feed on nectar.

For the cockroach, venom is nightmarishly potent stuff, and we humans are none too fond of it either. It can be a painful experience and you really should see what Justin Schmidt has to say about that. He let himself be stung by over 80 species of bees, ants and wasps and recorded the sensation for posterity. It’s like a connoisseur’s guide to pain. But to think only of pain would be to overlook venom’s amazing potential to do good. Venom is a very complicated cocktail of proteins and scientists like Glenn King over at the University of Queensland spend a lot of time isolating venom components that may be of benefit to us. How about a venom peptide from a painful biter like a centipede that might become a painkiller as potent as morphine yet is non-addictive? Or an insecticide derived from funnelweb spider venom that hits the pests yet leaves the bees? Bug venoms are a library that we are only just starting to read.

Dr Phil Sirvid looks after the entomology collection at Te Papa and has an inordinate fondness for spiders. He is one of the swarm of people that helped develop the Bug Lab exhibition.