PELLSTON, Mich. — When the sun is shining in June and July in northern Michigan, the cicadas are calling.
And when the cicadas sing, a decades-long researcher at the University of Michigan Biological Station is listening.
“This is a cicada which is here every year,” said Dr. Reinhard Lakes-Harlan, a professor from the University of Giessen in Germany. “It is a unique place.”
A neurobiologist by training, he studies ecophysiology at the field station — from the nervous system to other aspects of physiology. Specifically, his research focuses on the acoustic behavior and population dynamics of the cicada.
“There are very strict, distinctive roles for both sexes,” Lakes-Harlan said. “The male cicadas produce a calling song or sing. This is intended for the female. The females then fly to the cicada and then they may reproduce.”
But, like most things in life, it’s not that simple. The scientist and his research team uncovered a “spectacular” hidden story of disruption involving a parasitic fly that kills a whopping 80% of male cicadas annually and a cicada-targeting fungus that manipulates the insect’s behavior.
“Cicadas are kind of weirdly alien animals to begin with, and Dr. Lakes-Harlan’s work reveals they are even weirder with a fascinating interaction among cicadas, flies and fungi,” said UMBS Director Aimée Classen. “It’s like the northern Michigan insect version of the ‘Last of Us' — almost impossible to imagine until you see it with your own eyes.”
Lakes-Harlan holds up a SoundCam on Wednesday, July 3, at the U-M Biological Station to see where the singing cicadas are located at the top of nearby trees. The device depicts the location and intensity of sounds in a video image, indicated by the colored areas.
To attract activity, he sets out a small loudspeaker in a forest at the research and teaching campus about 20 miles south of the Mackinac Bridge, playing pre-recorded sounds like a male cicada’s calling song.
“Sometimes it’s cicadas, sometimes flies, sometimes fungus-infected cicadas,” Lakes-Harlan said of what lands on the speaker as well as his hat, shirt and pants.
Lakes-Harlan studies a three-species system: the interaction between the cicada Okanagana rimosa, a parasitic fly and a fungus.
“It’s quite a convenient place to study them here,” Lakes Harlan said.
Since the 90s, Lakes-Harlan has studied all different aspects of the biology in the system.
The students on his research team over the years aimed their attention at the parasitic flies. Last year an undergraduate student was at UMBS for four weeks to establish a method in the field to track the fly’s behavior. Three former Ph.D. projects on the biology and behavior of the fly were also based on studies here at UMBS.
The team found that the parasitic fly, which has an “ear” for the male cicada’s calling song (“which is quite unusual”), kills about 80% of the males in the early season.
When the parasitic flies are gone for the year, as they are now in early July, a fungus called Massospora levispora interferes and changes the behavior of both male and female cicadas.
Lakes-Harlan collected the specimen of a female cicada that died after a fungus infection in the Grayling area — “you can see the fungus replaced all of the abdomen.”
With a fungus infection, the male cicada changes its role entirely before it dies. It does not produce a calling song but flies to other calling males “probably to spread the spores for the fungus” to be able to infect more cicadas the next year.
And Lakes-Harlan also found that a fungus infection alters the nervous system of the female cicada so they are attracted to any random noise source, not just the male cicada’s calling song.
It’s this fungal intricacy and sophistication that keeps Lakes-Harlan curious about how life happens, or ends, for cicadas.
“I really want to analyze the signals from the cicada further,” he said. “For example, if there are two cicadas simultaneously singing or even more cicadas, how does the sound spread in the habitat? And how would a female know how to decide which male to go?”
More than 25 years into an investigation, unraveling the mystery of this three-species system centered by the cicada leaves this scientist marveling at the natural world.
“It’s so spectacular,” Lakes-Harlan said. “You can be proud to have such cicadas year-round. That’s why I come here to the northern part of Michigan. This is nature.”
Watch the video or scroll down to view photos.
Founded in 1909, the U-M Biological Station is one of the nation’s largest and longest continuously operating field research stations. For 116 years, students, faculty and researchers from around the globe have studied and monitored the impact of environmental changes on northern Michigan ecosystems.
The core mission of the Biological Station is to advance environmental field research, engage students in scientific discovery and provide information needed to understand and sustain ecosystems from local to global scales. In this cross-disciplinary, interactive community, students, faculty and researchers from around the globe come together to learn about and from the natural world and seek solutions to the critical environmental challenges of our time.
