Return of the zombie cicadas: Manipulative qualities of fungal-infected
flyers

Date:
July 27, 2020
Source:
West Virginia University
Summary:
Cicadas infected with the parasitic fungus Massospora unknowingly
engage in trickery with their fellow insects, resulting in effective
disease transmission, according to new research. Massospora
manipulates male cicadas into flicking their wings like females -
a mating invitation - which tempts unsuspecting male cicadas and
infects them.



FULL STORY ========================================================================== Cicadas infected with the parasitic fungus Massospora unknowingly engage
in trickery with their fellow insects, resulting in effective disease transmission, according to West Virginia University-led research.


========================================================================== Massospora manipulates male cicadas into flicking their wings like
females -- a mating invitation -- which tempts unsuspecting male cicadas
and infects them.

It's a recent discovery into the bizarre world of cicadas plagued by
a psychedelic fungus that contains chemicals including those found
in hallucinogenic mushrooms. The research, "Behavioral betrayal: How
select fungal parasites enlist living insects to do their bidding,"
was published in the journal PLOS Pathogens.

"Essentially, the cicadas are luring others into becoming infected because their healthy counterparts are interested in mating," said Brian Lovett,
study co-author and post-doctoral researcher with the Davis College of Agriculture, Natural Resources and Design. "The bioactive compounds
may manipulate the insect to stay awake and continue to transmit the
pathogen for longer." These actions persist amid a disturbing display
of B-horror movie proportions: Massospora spores gnaw away at a cicada's genitals, butt and abdomen, replacing them with fungal spores. Then they
"wear away like an eraser on a pencil," Lovett said.

Lovett compared the transmission of the behavior-modifying virus to
rabies.



==========================================================================
Both rabies and entomopathogenic fungi (parasites that destroy insects)
enlist their living hosts for successful "active host transmission,"
Lovett said.

"When you're infected with rabies, you become aggressive, you become
afraid of water and you don't swallow," Lovett said. "The virus is
passed through saliva and all of those symptoms essentially turn you
into a rabies-spreading machine where you're more likely to bite people.

"In that sense, we're all very familiar with active host
transmission. Since we are also animals like insects, we like to think
we have complete control over our decisions and we take our freewill for granted. But when these pathogens infect cicadas, it's very clear that
the pathogen is pulling the behavioral levers of the cicada to cause it
to do things which are not in the interest of the cicada but is very
much in the interest of the pathogen." Lovett's colleague and paper
co-author, Matthew Kasson, associate professor of plant pathology and
mycology, helped first discover the existence of psychoactive compounds
in Massospora-infected cicada fungi last year.

"Our previous literature always mentioned the strange behaviors associated
with Massospora and some closely-allied fungi but what was missing
was a synthesis of all this new information that had come to light,"
Kasson said. "The most interesting finding is the things we still don't
know. We realized that there were some possible scenarios for infection
that we had not considered before." Kasson noted that it's generally
accepted that cicada nymphs encounter Massosporain their 17th year as
they emerge from the ground to molt into adults. But researchers also
concluded that nymphs could encounter Massospora on their way down to
feed on roots for 17 years.



==========================================================================
"The fungus could more or less lay in wait inside its host for the next
17 years until something awakens it, perhaps a hormone cue, where it
possibly lays dormant and asymptomatic in its cicada host," Kasson said.

Working alongside Lovett and Kasson was doctoral student Angie Macias,
who believes their research will lead to a better overall understanding
of insects.

"These discoveries are not only super cool but also have a lot of
potential in helping us understand insects better, and perhaps learn
better ways to control pest species using fungi that manipulate host behaviors," she said. "It is almost certain that there are undiscovered Massospora species, never mind the other AHT (active host transmission)
fungi, and each of these will have developed its own intimate connection
with its host's biology." The team managed to research cicada broods
earlier this year in southeastern West Virginia.

Lovett also explained why we're seeing cicadas emerging again so soon.

"Different broods come out at different time spans," he said. "There's
our periodical cicadas that come out every 13 years and there are other periodical cicadas that come out every 17 years. The timing is staggered
in different states." And, as grotesque as an infected decaying cicada
sounds, they're generally harmless to humans, he said. They also reproduce
at such a rate that the fungi's extermination of hordes of cicadas has
little effect on their overall population.

"They're very docile," Lovett said. "You can walk right up to one, pick it
up to see if it has the fungus (a white to yellowish plug on its back end)
and set it back down. They're not a major pest in any way. They're just
a really interesting quirky insect that's developed a bizarre lifestyle."

========================================================================== Story Source: Materials provided by West_Virginia_University. Note:
Content may be edited for style and length.


========================================================================== Journal Reference:
1. Brian Lovett, Angie Macias, Jason E. Stajich, John Cooley, Jo/rgen
Eilenberg, Henrik H. de Fine Licht, Matt T. Kasson. Behavioral
betrayal: How select fungal parasites enlist living insects to do
their bidding.

PLOS Pathogens, 2020; 16 (6): e1008598 DOI:
10.1371/journal.ppat.1008598 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2020/07/200727145424.htm

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