A somewhat disturbing new study says that a single gene found in a caterpillar virus sends its victims running for the treetops, where they die and their bodies liquefy. This sends an ooze of death onto other caterpillars below, infecting new victims.
This species of baculovirus infects only gypsy moth caterpillars, basically morphing them into zombies. It stops the caterpillars from molting and sends them scurrying up into the tree leaves during the daytime, something they usually only do at night, where they die among the leaves as they wait to molt.
“They die there, and then they melt within hours after they die, and they are dripping virus down onto the leaves below,” said study researcher Kelli Hoover of Pennsylvania State University. “We knew before that this behavior benefits the virus, but we didn’t know how it was causing the behavior.”
A single gene in the virus causes this effect. The gene, named “egt”, seems to interfere with the caterpillar’s molting hormone and increases the caterpillar’s urge to climb.
Not only does this bizarre virus send the caterpillars crawling upward, it also stops them from molting. This aids the virus greatly as molting caterpillars don’t eat, don’t grow, and therefore produce less virus-containing slime.
These zombie caterpillars are just one example of how a parasite can control another organism. For example, fungus-infected zombie ants are lured to their death to spread their parasite. Similarly, a protozoan called toxoplasmosis makes infected mice approach cats, the parasite’s ultimate host.
It gets better- humans may not even be safe from such mind control.
“Who knew that a virus could change the behavior of its host?” study author Jim Slavicek, of the U.S. Forest Service, said in a statement. “Maybe this is why we go to work when we have a cold.”
Or maybe we just need the money, Jim. Either way, this is a nasty little virus.