Researchers from the Institute for Molecular Bioscience (IMB) of the University of Queensland in Australia have discovered the surprising ancestry of the venom of a species of caterpillar, but it could hold the key in improved drug delivery.

Unlikely Source of Caterpillar Toxin

Led by Dr. Andrew Walker and Professor Glenn King, the research team studied the behavior of Megalopygidae caterpillar, also known as asp caterpillar, with focus on the release of their harmful venoms. They found out that the toxins in this venom have the ability to punch holes in the cells of their host organism. This ability is also seen in the toxins released by E. coli and Salmonella, the species of bacteria that are known to cause various diseases in humans.

Walker and King have been studying different types of insects, and they were surprised to discover that the venom of asp caterpillar is different from the rest of the substances that they had observed in other insects. Upon close inspection, they found out that the proteins present in the toxins of caterpillar venoms are very similar to the toxins of some disease-causing bacteria.

The toxins from E. coli and Salmonella bacteria bind themselves to the surface of the cells and arrange into donut-like pattern that create holes. This is also a similar mechanism exhibited by the venom of box jellyfish.

Scientists believe that the venom in these caterpillars underwent evolution through gene transfer from bacteria over 400 million years ago. Various species of caterpillars have formed defenses against their predators, such as cyanide droplets and protective glues. Walker and his team are interested in discovering how such defenses might be related with each other.

Despite the damage and pain caused by venoms, they hold a key in pharmaceutical industry because they serve as rich sources of new molecules which can be developed into drugs. IMB researchers have investigated the venom of snakes and spiders, demonstrating their amazing potential in drug delivery. The type of toxins that can puncture holes in cells are of particular interest to scientists due to their ability to enter cells of other organisms. In the future, they could contribute to the development of beneficial drugs that target healthy cells, or those that selectively destroy cancer cells.

READ ALSO: Venom Origin: Why Do Insects and Fishes Dominate Diversity in the Animal Kingdom?


How Dangerous is Asp Caterpillar Venom?

Asp caterpillar, or the larva of Megalopyge opercularis, is considered to be one of the most toxic caterpillars in the North American region. Also known as puss moth caterpillars, this teardrop shaped larva grows from 1 to 1.5 inches long.

This insect is called stinging caterpillar, but its venom is actually contained in its spines that are connected to a poison bag and covered by the hair in its outer surface. When these spines are touched, they can break off and remain in the skin of the victim while releasing its harmful venom.

Within five minutes of contact, the victim could suffer from intense throbbing pain extending up the affected area. The person could experience other symptoms such as headaches, lymphadenopathy, nausea, intense abdominal stress, vomiting, lymphadenitis, or even respiratory stress. Spots or papules could also appear at the spot of the sting which can last up to 5 days.

 

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