Yuka -- The Caterpillar Assassin!

Palio week at last!!!  


At the horse trial, we saw all the contradas that are selected this year: The Eagle, Caterpillar, Wave, Forest, Dragon, Unicorn, Turtle, Snail, Shell, and Giraffe. While William was in great support of Dragon and Wave, I decided to support the Caterpillar. So then an argument goes all the way from "dragons are more mystical" to "dolphins eat caterpillars"... No. Dolphins don't eat caterpillars. But even if they do, these small little creatures have their own ways to kill big predators in the world.  

Bruco - The Caterpillar Contrada

In order to protect their cute little bodies from numerous predators, caterpillars have a few lines of defense. They can warn off large animals by their bright toxic colors and body markings as a first line of defense. When they are attacked, some will activate second line defense reponses such as releasing poison. Other aggressive caterpillars may combine both defense bristles with venom glands. The South American silk moth, genus Lonomia, produces one of the most potent defensive chemicals in any animal, enough to kill an adult human (or an adult dolphin)!

Deadliest of the Deadly Lonomia - Lonomia obliqua

The caterpillars of genus Lonomia has caused 354 cases of poisoning in Brazil between 1989 and 2005. These caterpillars are even more toxic and dangerous than rattlesnakes, since data has shown fatility rate by rattlesnake bite is 1.8% and by Lonomia is 1.7% while using 0.001% of what a rattlesnake uses! Its venom act as an anticoagulant (interferes with blood clotting) which is powerful enough to kill humans. Most poisoning occur when people rub against multiple Lonomia caterpillars as they pass by a tree, leading to severe pain, kidney failure, and hemolysis. In severe cases, this venom works to cause intense bleeding (or hemorrhaging) in the skull, also known as intracerebral hemorrhage. This is due to the anticoagulants inside the venom, which increases the chances of intracranial bleeding.

Intracerebral hemorrhage - brain will gradually squeeze through the skull...

Interestingly, this deadly poison has its beautiful and valuable side in medication. Lonomia is studied in medicine for its anticoagulation properties; scientists try to use chemicals in the venom as in vivo medication for thrombotic disorders. Unfortunately, the specific chemical makeup of the poison is still not entirely understood yet. Previous studies done by da Silva GH et al. took samples of the Lonomia venom and injected it intravenously to rats. Light and electron microscopy were used to detect the morphological alterations in the brain and blood-brain barrier, and cases of leaky vessels and intracerebral hemorrhage were seen.

Still many studies are carried out to understand the mechanism of envenoming by these deadly caterpillars. Several toxic principles were found in bristle extract and the hemolymph, and some have more than one function. It still amazes me how such natural poison is a valuable pharmeceutical compound that will be useful in preventing life threatening blood clots. More natural products will be used in medicine in astonishing ways, and hope after this great study abroad trip I can continue to learn more about these natural medicines!

References:
"On The Conditional Nature of Neotropical Caterpillar Defenses Against Their Natural Enemies" - Ecology
"Lonomia obliqua caterpillar venom increases permeability of the blood-brain barrier in rats" - Toxicon