Cicadas (Magicicada spp.)
This post is a little PG-13. Everyone loves a great parasite story right? Or love the Aliens movie series with the face huggers? Well you don’t have to go to a galaxy far far away, you can stay on your own planet even to find some pretty remarkable interspecies relationships.
There is a variety of parasitic species including viruses, nematode-like horsehair worms and fungi which modulate the behavior of their hosts. In most cases the parasites have traits which maximize dispersal once they have infected their host. The most-well known example of this is “summit disease” behavior where the insect, infected by a fungi, ascends and affixes itself prior to death to the top of the substrate. Based on location it is more likely to be consumed by something further up the food chain. Once this consumer dies, the sporulation from the mummified carcass can occur, permitting dispersal of the fungi all over again. Ants can be infected by these types of entomopathogenic (insect-infecting) fungi, causing them to climb to the tops of grass blades, affix themselves, die and be eaten by ruminants like cows and sheep.
It gets even more interesting, even more niche parasitism at its finest. The Entomophthorales (Zoopagomycota) are insect infecting species which also extend “active host transmission” (AHT), where the fungus maintains or accelerates some host activity during sporulation. For the parasitic-fungi this maximizes their dispersal. The Massospora are a sexually transmittable pathogenic fungi species that infects a variety of cicadas (Hemiptera). When cicadas become infected the spores which have replaced the insects genitals, actively spread from the abdomen, during flight and while mating. On top of that Massospora -infected cicadas are in sexual over-drive, and even make sexual attempts at conspecific males. Essentially this rare fungus turn the unsuspecting cicadas into castrated sex-crazed butt fungus zombies. Interestingly but not all together unsurprisingly, the mechanisms of the underlying AHT behavior is poorly understood.
Fortunately, some West Virginia University researchers are preparing for the cicada-zombie apocalypse and have been studying the chemicals produced by the entomopathogenic Massospora species.
“They are only zombies in the sense that the fungus is in control of their bodies,”
said Matt Kasson, assistant professor of forest pathology and one of the study’s authors.
“Infected adults maintain or accelerate normal host activity during sporulation, enabling rapid and widespread dispersal prior to host death,” Kasson said. “They also engage in hypersexual behaviors.”
Kasson and the research team did a metabolomics study (the scientific study of chemical processes involving metabolites, the small molecule substrates, intermediates and products of metabolism), in order to identify some candidate molecules potentially contributing to the cicada’s hypersexual behavior.
The study was recently published in Fungal Ecology and using metabolomics, identified plant-associated amphetamine, cathinone, in four Massospora cicadina-infected cicada populations, and also the mushroom-associated tryptamine, psilocybin. How crazy is that? So, they are actually castrated sex-crazed butt fungus cicada zombies tripping on mushrooms and amphetamines.
To read this fascinating study for free and learn much more about the underlying candidate metabolites and their potential effects on insect behavior please find the journal article link here.
Boyce, G.R., Gluck-Thaler, E., Slot, J.C., Stajich, J.E., Davis, W.J., James, T.Y., Cooley, J.R., Panaccione, D.G., Eilenberg, J., Henrik, H. and Macias, A.M., 2019. Psychoactive plant-and mushroom-associated alkaloids from two behavior modifying cicada pathogens. Fungal Ecology, 41, pp.147-164.
