Imagine that there is a virus that could kill you, but before it does…controlling you to go out and infect those around you. This virus exists, at least in less caterpillars, and a team of researchers determined the virus genes responsible for this zombie-like behavior.
A gypsy moth leads a life of simplistic routine. Every night, it crawls into the trees to feed on its leaves…and every day it returns to the ground below to protect itself and avoid predators. This routine is altered, however, when the gypsy moth is infected with the baculovirus.
When the caterpillar is infected with the zombie-like baculovirus, it is being internally controlled and fed upon by it.
The zombie catepillar, with what little energy it has left, climbs the trees in the daytime instead of at night and infects the folliage in that area…and so infected the rest of the caterpillar population.
How does this happen? As the catepillar is in the treetops, it dies and then liquefies. In doing so, it spreads the baculovirus over the folliage, infecting any future catepillars that come in contact with it at night.
A research team led by Kelli Hoover, an entomologist, hypothesized that the behavior of the infected caterpillars might be traced to a gene in the virus called egt. Coded for the enzyme, EGT, this gene disables the hormone that triggers the caterpillar to molt. Being that they molt only on the ground (at night), the research team reasoned that they stayed in the trees because because the instinct to go to the ground to molt was not there.
Hoover and her team tested this hypothesis by extracted the egt gene from the virus and infected caterpillars with the modified and unmodified viruses.
Having observed the caterpillars until their liquidy death, they concluded that extraction of the egt gene was, in fact, the gene responsible for the zombie-like behavior in the infected caterpillars.
The researches say that their findings prove that there is a genetic basic for the modified caterpillar behavior.
“One of the best ways to control complex behavior is to manipulate hormones,” said Hoover. “In this case we’ve found that that the gene also somehow induces the caterpillars to go to just the right location to enhance transmission of the virus to new hosts.”