Lady Bug Zombies

There exists, in the insect kingdom a parasitic wasp that can deploy a virus to enact a mind-control weapon. The wasp literally injects a virus into ladybugs and turns them into zombie bodyguards for its young, a new study says.

The D. coccinellae paralysis virus marks the first known virus or other microorganism “involved in a behavioral manipulation that benefits another species,” said study co-author Nolwenn Dheilly, a biologist at Stony Brook University in New York.  After being injected into the ladybug along with the wasp’s egg, the virus replicates inside the growing wasp grub, which feeds on the insect’s fluids. When the grub is ready to emerge and pupate, the virus infects the ladybug, causing paralysis.

Although the study team was able to detect the virus only in the ladybug’s brain, “we believe it is able to infect the whole nervous system,” said Dheilly, whose research appears in the journal Proceedings of the Royal Society B.  Once immobilized, the ladybug stands guard over the silk cocoon. Since ladybugs are predators and contain toxic fluids, they make good bodyguards, but the DcP virus may actually enhance their deterrent effect by making them twitch.

Dheilly thinks the virus is responsible for this twitching behavior, even if the link is yet to be demonstrated. “Tremors are associated with many neurodegenerative disorders,” she said. “Indeed, the virus load could directly participate in the duration of the paralysis and the tremors” seen in zombified ladybugs.

According to Dheilly other parasitic wasps are known to use viruses as weapons, but these polydnaviruses are different from DcPV as they only help to knock out the immune defenses of caterpillars and other hosts.  Polydnaviruses have co-evolved with their particular wasp species in such a close way that their DNA is integrated within the genome of the wasp. These differences have given some scientists pause to consider whether or not DcPV and others can be called viruses.


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