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Cicadas are coming, bringing mysteries that fungus scientists hope to study

This spring and summer, residents of parts of the Midwest and Southern United States will have the opportunity to experience a digitally magnificent wildlife event: a rare double emergence of periodical cicadas. With the arrival of Brood XIX and Brood XIII, billions of harmless, carrot-sized insects will sing their hearts out, from Wisconsin to Louisiana, Maryland to Georgia, and many places in between.

The last time these broods co-emerged was 1803, Thomas Jefferson was president, and the Louisiana Purchase had just been finalized – meaning many states where cicadas’ love songs soon to fill the air weren’t even officially part of the nation yet.

As impressive as it may seem, this year’s entomological phenomenon will be very special for researchers hoping to unravel the evolutionary mysteries of insects that only emerge from the ground at intervals of about 13 or 17 years.

Broods are not the same as species, and each brood may contain several species of cicadas that may emerge in different locations. In 2024, all seven species of cicadas will be represented, a coincidence that will not happen again until 2037.

This means that this year’s emergence will be a gold mine when it comes to data collection.

One of the more unusual mysteries scientists hope to investigate involves a parasitic fungus that attacks adult cicadas, turning them into what one expert calls “flying salt shakers of death.”

“So it’s pretty spectacular, from the point of view of a scientist interested in cicadas,” said Matt Kasson, a mycologist at West Virginia University.

Cicadas are true insects of the Hemiptera insect family. Famous for their repetitive mating calls, adult cicadas are large, noisy and very visible. But most of a cicada’s life is spent underground as a nymph.

Cicada nymphs are probably among the most underappreciated forest herbivores, as most of the time they are out of sight and make their living by sucking sap from the roots of trees and other plants. They emerge in spring or summer, when the ground about a foot below reaches 64 degrees. The nymphs then climb the nearest vertical object and molt into their adult form. These winged adults spend their brief but eventful lives mating and, for females, laying eggs.

Cicadas can be divided into two general types: annual cicadas, which tend to have black or green eyes and can be heard every year, and periodical cicadas, which usually have red eyes and only appear every 13 or 17 years old.

Although they are nymphs, these long-lived insects must escape the cold by burrowing below the frost line. In some parts of their range, such as Wisconsin, this can mean living more than five feet below the surface.

This makes each emergence important for scientists. If a researcher studying a species of zebra or puffin wants to collect genetic samples, they may have to endure hostile environments or perilous journeys, but at least these animals are almost guaranteed to be around in any given year . The same is not true for a given species of cicada. Technically they may be there, but they are too deep underground to be easily found and accessed without causing significant harm to animals. (Kasson said he tried, and he didn’t succeed.)

Additionally, cicada broods generally do not synchronize; It’s been nine years since something like this happened. And when they overlap in time, they tend to spread out in space, with emergences occurring several states away from each other.

This means that certain questions can only be studied in certain places and at certain times, depending on what broods are on deck that year and what species they contain.

This year, however, the cicadas of Brood XIX and Brood XIII will compete, primarily in Illinois. And this is where things get scientifically exciting.

Casson hope to study a parasite afflicting cicadas known as Massospora. When this fascinating fungus infects an adult cicada, it floods the insect with amphetamine and psilocybin, each of which appears to influence its behavior.

For example, although the fungus has invaded the lower third of its body, replacing its abdomen and genitals with fungal tissue, the cicada does not appear to feel any pain. Instead, the infected cicadas seem to want to party.

“There is some hypersexual behavior,” Kasson said. “Males pretend to be females to lure other healthy males to come and try to mate with them. And this is probably a strategy of the fungus to increase the number of individuals it is able to infect.

The parasite typically affects less than 5 percent of a given cicada population. But once infected, these chalky white abdomens shed spores wherever they go.

Kasson is attempting to conduct genetic work to learn more about how the fungus persists in animals with such unusual and disjointed life cycles. This year he will be able to collect contemporary samples from a 13-year-old brood for the first time (old and archived specimens have been used in the past), which could yield interesting results.

“Although we have limited data, some DNA sequence data from the 13-year-old broods are somewhat different from those from the 17-year-old broods, and I wonder if there actually are genetic differences between the strains,” did he declare.

Researchers are also interested in the fungus as a source of new drugs, Kasson added. It has been used as a traditional form of medicine for inflammation in the Maori cultures of China and New Zealand.

Since Brood XIX and Brood XIII overlap in very few areas, it is unlikely that any location will experience twice as many cicadas as usual. (With several million cicadas emerging per square acre, doubling that figure would be, well, intense.) It’s also unlikely that most people will notice a difference between broods in areas where the two are adjacent.

“They look identical. They look identical. And genetically, they’re pretty much identical,” said Chris Simon, an evolutionary biologist at the University of Connecticut.

It’s not always the case. For example, Magicicada neotredécim is a 13-year-old cicada that will emerge this year as part of Brood XIX in Illinois. This species is almost twice as large as Magicicada septendeculawhich will also emerge as part of Brood XIII, appearing a little north in Illinois, as well as Iowa and Wisconsin.

For scientists like Simon, the real opportunity lies in much less obvious distinctions. She wants to learn more about how cicada broods count years, something she is trying to understand by sequencing entire genomes and looking for genes or groups of genes that control whether a cicada follows the cycle of 13 or 17 years old.

“One of the most interesting things is that we thought the age classes, or broods, were reproductively isolated, because we thought they had an exact life cycle and the adults would never see each other “, said Simon. “But it turns out that’s not accurate, and sometimes they come out four years early, or four years later.”

This means that different broods can still exchange genes with each other, which will likely contribute to the future evolution of the species.

“When 13-year-old and 17-year-old cicadas come out in the same year, you can really do hybridization experiments,” Simon said. The last time she had the opportunity to do such work was in 2015, and in 1998 before that.

Simon added that inaccuracy in cicada timing would be increasing due to climate change, which is extending the nymphs’ growing season underground. Likewise, climate change may affect their distribution, as evidenced by Brood VI becoming increasingly established in the Washington area in recent years, she said.

Sometimes, over the course of hundreds of thousands of years, broods of 17-year-old cicadas transform into broods of 13-year-old cicadas.

Other scientists want to better understand how cicadas affect the plants they feed on, as well as how trees defend themselves against herbivores. Some studies show, for example, reduced growth of tree rings, as well as reduced yields in orchards, where cicadas are present.

However, the emergence of cicadas also has ecological benefits, providing an assortment of proteins for predators, as well as increased phosphorus and nitrogen for plant life, thanks to the billions of decomposing insect bodies. According to a 2005 study, cuckoos have more offspring in the years after cicadas emerge, while other bird species, such as crows, appear to fly away from emergences, presenting another ecological conundrum. .

If you’re outside during this year’s emergence and your dog or toddler swallows a cicada or three, don’t worry, said Maureen Turcatel, insect collections manager at the Field Museum in Chicago. Cicadas cannot bite or sting and are perfectly edible.

“It’s going to be loud,” Turcatel said, “but especially for the 13- and 17-year-old cicadas that come out in Illinois, it’s going to be a unique experience.”

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jack colman

With a penchant for words, jack began writing at an early age. As editor-in-chief of his high school newspaper, he honed his skills telling impactful stories. Smith went on to study journalism at Columbia University, where he graduated top of his class. After interning at the New York Times, jack landed a role as a news writer. Over the past decade, he has covered major events like presidential elections and natural disasters. His ability to craft compelling narratives that capture the human experience has earned him acclaim. Though writing is his passion, jack also enjoys hiking, cooking and reading historical fiction in his free time. With an eye for detail and knack for storytelling, he continues making his mark at the forefront of journalism.
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