Caterpillar venom reveals toxins borrowed from bacteria

11 July 2023

IMB researchers have discovered the venom of a notorious caterpillar has a surprising ancestry and could be key to the delivery of lifesaving drugs.

A team led by Dr Andrew Walker and Professor Glenn King found toxins in the venom of asp caterpillars punch holes in cells the same way as toxins produced by disease-causing bacteria such as E. coli and Salmonella.

“We were surprised to find asp caterpillar venom was completely different to anything we had seen before in insects,” Dr Walker said.

Working like box jellyfish venom

Colllection of caterpillar venom
Venom is collected by lightly pressing on the caterpillar's back

“When we looked at it more closely, we saw proteins that were very similar to some of the bacterial toxins that make you sick.”

This type of bacterial toxins bind themselves to the surface of cells and assemble into donut-like structures that form holes.

“It’s similar to the mechanism of box jellyfish venom – and as we’ve now found – caterpillar venom too,” Dr Walker said.



Genes transferred 400 million years ago

Caterpillar sting on hand
The sting of the asp caterpillar is likened to touching hot coals

“The venom in these caterpillars has evolved via the transfer of genes from bacteria more than 400 million years ago.”

The asp caterpillar (Megalopyge opercularis, larva of a moth) is native to North America, where it is often found in oak or elm trees.

It might look innocuous, but its long hair-like bristles conceal venomous spines that can deliver an excruciating sting likened to touching burning coal or blunt force trauma – often sending victims to hospital.

“Many caterpillars have developed sophisticated defences against predators, including cyanide droplets and defensive glues that cause severe pain, and we’re interested to understand how they are all related,” Dr Walker said.

Rich source of molecules for medicines

ASp caterpillar
The long hair of the asp caterpillar conceals venomous spines

“Venoms are rich sources of new molecules that could be developed into medicines of the future, pesticides, or used as scientific tools.

“IMB’s investigations into the venom of snakes and spiders have already demonstrated their amazing potential, but caterpillar venoms are particularly understudied.

“Toxins that puncture holes in cells have particular potential in drug delivery because of their ability to enter cells.

“There may be a way to engineer the molecule to target beneficial drugs to healthy cells, or to selectively kill cancer cells.”

This research was published in Proceedings of the National Academy of Sciences (PNAS).