Tobacco-nibbling larvae exhale nicotine in face of predatory spiders
Courtesy of Pavan Kumar
Eating wild tobacco plants produces such noxious breath in hornworm caterpillars that predators reel backward and flee upon encountering it.
“I think it’s actually the first example of using bad breath as a defense, although I’m sure that everybody has had a personal encounter of something similar,” says Ian Baldwin of the Max Planck Institute for Chemical Ecology in Jena, Germany.
As a plant defense, nicotine works by poisoning a variety of creatures. But the plump, striped tobacco hornworm caterpillar (Manduca sexta) can repurpose the poison to generate “toxic halitosis,” Baldwin says.
When a hornworm feeds on a wild tobacco plant, a touch of the plant’s nicotine is diverted into the insect equivalent of a bloodstream. Baldwin and his colleagues identified a gene that is involved in diverting 0.65 percent of ingested nicotine to create smoker’s breath strong