I know that parasitic wasp larvae could live for a long time inside their alive host (eg. caterpillar), but I always thought that they kill the host when they eventually get out of it. But once I've seen this film, where it's shown that not only a caterpillar can survive emerging of wasp larvae, but also the parasites infect the host with some kind of virus that changes the behaviour of the caterpillar to protect wasps' pupae. Is it possible and common among parasitic wasps? What species of wasps and viruses cause such effect?


The species of wasp you're referring to is Glyptapanteles. I'm not sure which virus it is.


Is it possible? Of course, you have an example! Though, there is a small caveat. Some of the offspring sacrifice themselves to induce the behavioral change after the rest of the brood has emerged.

Is it common among parasitic wasps? No. While injecting offspring into host species is a common theme for parasitic wasps, and while there are a handful which somehow induce behavioral changes in the host animals - continuing the manipulation after leaving the host animal is extremely rare among parasites in general.

  • $\begingroup$ Thanks! It's even more fascinating, because of altruistic motive (unless polyembryony was common among Glyptapanteles so that all larvae in one host will be genetically the same). I ask if such change in behaviour is possible, because I don't completely trust the information in popular science sources. I would accept your answer, but first I'd like to wait, maybe someone will find anything about that mysterious virus. $\endgroup$ – Marta Cz-C Aug 24 '12 at 14:56

In the study by Whitfield 1990 (1) I found the information that the parasitic wasp from family Ichneumonidae have interesting symbiotic viruses called polydnaviruses. This virus stay as provirus in the wasps genome and is transmitted vertically between subsequent generations of parasitoid. It does not harm the wasp and it is transmitted to the wasps hosts (usually caterpillar). The virus does not replicate in the caterpillar, but alter it's physiology: supress immune response and metamorphosis and increases the amount of nutrients in caterpillars hemolymph.

Still, I have not found any references about this kind of virus altering the behaviour of the caterpillar after the emergence of wasps larvae.

[1] Whitfield, J. B. (1990). Parasitoids, Polydnaviruses and Endosymbiosis. Parasitology Today, 6(12), 381-384. (free PDF)


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