I’m like a fungus; you can’t get rid of me.

~Adam Baldwin

Yesterday’s blog on Brood XIX was a brief summary of what I have been doing the past several evenings as I marvel at this occurrence. There are two things I had hoped to find in this year’s emergence after reading more about these amazing insects – a blue-eyed adult (a rare genetic oddity) and one with a fungus-infected rear end. I still haven’t seen a baby blue-eyed bug, but I have found one with a white butt. Oddly, I carried something from the front porch inside and when I walked back into the foyer, there was a cicada crawling on the floor (a hitch hiker on that package I carried in I suppose). I picked it up and was going to release it outside when I saw its rear was white. The fungus!

A stage 1 infection of this fungus on a cicada shows up as a whitish coating on the lower third of its abdomen. This fungus has a bizarre life history, matching that of its “prey”, the periodical cicadas (the fungus is known to infect both 13-year and 17-year periodical cicadas). I found a transcript online of an interview with Dr. Matt Kasson, an associate professor of forest pathology and mycology at West Virginia University. He has been studying this unique fungus for a number of years and described some of its unusual characteristics. Unlike other types of so-called zombie fungi (they alter the behavior of their host to create conditions better for spore dispersal) in which the death of the host is the usual means of better spore dispersal, this fungus exhibits active-host transmission. It keeps the host alive in order to better spread the spores. It does this by altering the cicadas behavior. He called the behavior hypersexualization. Male cicadas with the fungus will try to mate with females but will also exhibit the female behavior of wing flicking which creates an audible snapping sound. Uninfected males do not wing flick. Females do this in response to the male calls. This causes other male cicadas to try to mate with the infected males, enhancing the chances for fungal dispersal. One paper suggested this is a type of STD for cicadas!

Later in the emergence, cicadas infected with the Stage 1 phase of the fungus begin producing resting spores as part of the Stage 2 phase of the infection. These resting spores spread onto to the ground and will infect the next generation of cicadas that will emerge from the soil 13 or 17 years later. Scientists aren’t sure whether the hatching larvae pick up the resting spores as they burrow into the soil to feed on tree roots or whether the next generation of nymphs picks them up when they tunnel to the surface to emerge (or whether both occur).

One result of the fungus is that portions of the abdomen fall off of infected individuals. I have noticed a few cicadas with half their abdomen missing and initially thought this was from predation. After learning more about the infection, I picked one up and looked closely and saw white coloration inside the remaining body cavity. Is this the fungus? This morning, I sent photos of both cicadas to Dr. Kasson for his assessment of whether these are infected individuals. He quickly responded and confirmed the one in the first photo at the top of this page is indeed an infected cicada and he would like the sample. The other one is too damaged to determine from the photos. If you have any Brood XIX cicadas you suspect of being infected, you can contact him at mtkasson@mail.wvu.edu.

The more I learn about fungi, the more I think that they truly are the life form in control of this planet. Or is it just that they want me to think that?