Creepy, fascinating, and just plain “wow-inspiring”, fungi that can control the behavior of insects are an incredible story from the files of evolution. This moth likely met the end of its life at the hand (or mycelium?) of a Cordyceps fungus. Cordyceps is a genus of ascomycete fungi with at least 400 recognized species that are parasites of insects, arthropods, and other fungi. A group of us came upon this unfortunate moth during a student course to Costa Rica that I led in January 2012. We found it just days after one student had put finding one of the infamous fungi-infested insects at the top of her list. (I wish she had given us her complete top ten list, we may have seen even more incredible things than we did.)
Although we couldn’t be completely certain that it was a Cordyceps infection, there were several tell-tail signs that it was. First of all, the dead moth has a bunch of threadlike, fruiting bodies extending in all directions, which are responsible for dispersing spores. Second, the moth died in an exposed location, which may have been orchestrated, zombie-like, by the fungus itself. Cordyceps is known to have the ability to control an insect’s end-of-life wanderings, which it benefits from by increasing the likelihood that its spores are dispersed to new hosts.
Want to watch a Cordyceps infection in action? Take a look at this incredible video clip:
So what’s an insect to do in the face of such a formidable parasite? A recent study of ant colonies in Brazil found that there is a different parasite that uses Cordyceps as a host and essentially “castrates it” before the infection is complete. This three-species interaction is another good example of the ecological complexity out there in the world that we are still, slowly getting a handle on.
If anyone has other ideas about what caused the demise of this moth, please let me know.