Zombie Virus Takes Over and Liquifies Caterpillars

Baculovirus. There's a scary word. And it should be. A specific species of baculovirus hypnotizes its victims and causes them to climb up a tree where they will stay until impending doom. Liquefaction.

Luckily the only animals who have to fear the dreaded baculovirus are invertebrates -- so you're safe. This species of baculovirus in particular only affects gypsy moth caterpillars are common prey.

As reported by National Geographic, Kelli Hoover, an entomologist at Penn State University and co-author of a recent study that identified the gene that helps turn the prey into goo, said gypsy moth caterpillars generally go up into trees at night to feed on leaves but come back down during the day to hide. National Geographic has more on the 'zombie' virus:

"When they are infected, as they get sicker they stay up in the trees and die up there," Hoover explained.

The virus "ends up using just about all of the caterpillar to make more virus, and there are other genes in the virus that then make the caterpillar melt. So it becomes a pool of millions of virus particles that end up dropping onto the foliage below where it can infect other moths that eat those leaves."

At this point, you may now start feeling sorry for the the gypsy moth -- common prey of many baculoviruses -- don't. Gypsy moths are introduced to the United States by a French researcher in 1868. Since then they've been wreaking havoc on hardwood trees in the eastern United States.

Scientists recently were able to identify the gene -- called egt -- that allowed the virus to take over the caterpillars neurologically, turning them into zombies:

Researchers removed egt from some viruses, reinfected the caterpillars, and found that the zombie behavior stopped. When the team inserted the gene into a virus that previously lacked it, the zombie behavior returned.

"Somehow or other, using this gene, the virus is able to manipulate the behavior of the caterpillar to go to the right location in the tree to enhance transmission to new hosts. It's really amazing," Hoover said.

The gene may work by deactivating its hosts' molting hormone, according to the study, published tomorrow in the journal Science.

"That would be an advantage to the virus because it keeps the insect in a feeding state, so that they get bigger and bigger and make more and more virus."

Live Science reports that some forestry services have used the virus to help control the population of gypsy moth caterpillars. Even Hoover had a tree infected with the moths in her backyard at one point.