Parasitic viruses, oh my!

I love Ed Yong’s blog, Not Exactly Rocket Science. He’s joined Alton Brown as a charter member of my Geeky Crush Club.

This one’s about parasites that influence the behavior of their hosts, including driving them to their deaths.

At the top of its plant, the caterpillar liquefies. Its body almost seems to melt. As it does, it releases millions of viruses, dripping them onto plants below and releasing them into the air. These viruses are the agents that compelled the caterpillar to climb, and eventually killed it. They are baculoviruses, and they cause a condition known aptly as Wipfelkrankheit – the German for “tree top disease”.

The baculoviruses are just some of the many parasites that change the behaviour of their hosts, and many of them trigger unusual tendencies to climb. The fungus Cordyceps unilateralis drives ants to bite into leaves around 25 centimetres above the forest floor. This zone has the perfect conditions for the fungus to develop its spore capsule, which erupts fatally through the ant’s head. Meanwhile, the Leucochloridium fluke cancels out a snail’s fear of bright lights, driving them to open spaces where they’re more readily eaten by birds – the fluke’s final host. Perhaps someday, scientists will decipher the genes that allow these parasites to take over minds as well as bodies.

3 thoughts on “Parasitic viruses, oh my!”

  1. And you know there have been scifi novels that have taken this idea and run with it…can’t think of any in particular off-hand, but I just know they exist.

  2. Yep, there have been a lot of stories/books/TV/movies about alien symbiosis and parasitism. And of course there are the non-biological nanobots. I did a very short google search for virus/fungal parasitism causing behavioral changes and hit on this short story:

    Being David Brin, the science is heavy, but it covers the exact topic described in your article. Also, it has been a while since I read the Ender series, but I seem to remember a virus in Speaker for the Dead…just can’t remember if it caused behavioral changes or just biological ones.

Comments are closed.