Caterpillar uses nicotine breath to ward off enemies
SUMMARY: The hornworm caterpillar consumes nicotine-filled leaves of tobacco plants to deter enemies from eating it. Who can blame them?
Posted: January 7, 2014
We all knew bad breath could scare away potential dates, but the hornworm caterpillar employs it to fight off predators.
The tobacco hornworm, scientifically referred to as the Manduca sexta, spends most of its time crawling over its favorite plant - the tobacco plant. It consumes the nicotine-replete leaves, digesting them and exhaling any excess nicotine in its body, new research has found.
Study leader Ian Baldwin explained to National Geographic that nicotine is the reason behind the caterpillar's foul breath. Baldwin pointed out that a unique gene in hornworm caterpillars allows them to expel nicotine through their spiracles (tiny holes in their sides). Researchers labeled this strategy "defensive halitosis."
Wolf spiders and other predators that generally eat the hornworm are engulfed by the odor, considering it potentially poisonous. Importantly, this is the first discovery of halitosis demonstrating an animal's toxicity.
"It's really a story about how an insect that eats a plant co-opts the plant for its own defense," Baldwin told National Geographic.
The nicotine defense
Before humans ever learned to harvest, cure and smoke tobacco, the central chemical of nicotine served as a defense mechanism for the plant. Animals that consume its leaves experience inhibited body function. Nicotine, which millions of Americans know as the main ingredient of cigarettes, aims at the neuromuscular junction, the spot where nerve cells meet muscles, in animals. Thus, when an animal - with the mysterious exception of the hornworm caterpillar - eats a plant that contains nicotine, its movement and breath become hindered.
"This is why nicotine is such a great defense for plants: it poisons everything that uses muscles to move, and since plants don't have nerves or muscles, it doesn't poison the plant," Baldwin remarked to the source.
It all adds up. The very ingredient which we know to cause countless diseases and health problems in humans evolved from a role as a chemical defense in plants. Cigarettes, cigars and smokeless tobacco all fall under this category.
Perhaps the most immediately noticeable drawback of smoking is its stench. If you've ever been around someone who's puffing cigarettes, you've likely had a run-in with smoker's breath. On top of leaving odor-causing bacteria on teeth and gums, smoking almost always triggers dry mouth, creating a lack of saliva - and more bad breath.
Early and late stage gum disease also afflicts smokers. In fact, those who use tobacco products have the greatest likelihood of developing these ailments.
Much like the hornworm caterpillar, humans are susceptible to nicotine's smelly and deterring by-product.