The last time these companions appeared together was in 1803, when Thomas Jefferson was president and the Louisiana Purchase had just been completed. That means many of the states where cicada love songs would soon fill the air weren’t even officially part of the Louisiana Purchase. No nation yet.
That’s impressive, but this year’s entomological phenomenon will be special for researchers hoping to unravel the mysteries of the evolution of insects that only emerge from the earth every 13 or 17 years.
Chicks are not the same as species, and each chick may contain multiple cicada species that may emerge in different locations. In 2024 all seven species of cicadas will appear, but this coincidence will not occur again until 2037.
In other words, this year’s emergence will be a treasure trove of data collection.
One of the more unusual mysteries that scientists want to investigate involves a parasitic fungus that attacks adult insects and turns them into what one expert calls a “flying salt shaker of death.”
“From the perspective of a scientist interested in cicadas, this is pretty cool,” said Matt Casson, a mycologist at West Virginia University.
Cicadas are true insects in the order Hemiptera of the insect family. Famous for their repeated courtship calls, adult cicadas are large, vocal, and highly conspicuous. However, cicadas spend most of their lives underground as nymphs.
Cicada larvae are perhaps one of the most underappreciated forest herbivores. That’s because cicada larvae are mostly hidden away and make a living by sucking sap from the roots of trees and other plants. They appear in the spring or summer when the soil about 1 foot underground reaches 64 degrees. The nymph then climbs onto the nearest vertical object and molts into its adult form. Winged adults lead a short but noisy life, mating and, in the case of females, laying eggs.
Cicadas can generally be classified into two types. One is the annual cicada, which has black or green eyes and whose call can be heard every year, and the other is the periodic cicada, which usually has red eyes and emerges only every 13 or 17 years.
Although these long-lived insects are nymphs, they must escape the cold by burrowing below the frost line. In some parts of its range, such as Wisconsin, it can live more than 5 feet below the surface.
This is why every appearance is important to scientists. Researchers studying zebra and puffin species who want to collect genetic samples may have to endure harsh environments and dangerous journeys, but at least they know that these animals exist in any given year. Almost guaranteed. The same does not apply to certain cicadas. While it may technically be there, it’s so deep underground that it can’t be easily found or accessed without seriously harming the animal. (Casson said he tried, but the results came up empty.)
Additionally, flocks of cicadas are usually not synchronized. It’s been 9 years since something like this last happened. And if they overlap in time, they tend to spread out in space, with occurrences occurring several states apart from each other.
This means that some questions can only be investigated at certain times and in certain locations, depending on which chicks are on deck that year and which species are included.
But this year, Brood XIX and Brood XIII cicadas will be pitted against each other, primarily in Illinois. This is where things get scientifically interesting.
Casson I want to study A parasite that afflicts cicadas known as Massospora. When this fascinating fungus infects adult cicadas, it releases large amounts of amphetamine and psilocybin into the insect, each of which appears to affect the cicada’s behavior.
For example, cicadas don’t seem to feel pain, even though fungi occupy the lower third of their bodies and fungal tissue replaces their abdomens and reproductive organs. Instead, the infected cicadas seem to want to party.
“There is some excessive sexual behavior,” Casson said. “Males pretend to be females and try to attract other healthy males to mate with them. And that’s probably a strategy by the fungus to increase the number of individuals it can infect.”
This parasite typically affects less than 5 percent of a given cicada population. But once infected, its chalky white belly spreads spores everywhere.
Professor Casson plans to carry out genetic studies to learn more about how fungi persist in animals with such unusual and disorganized life cycles. This year, for the first time, he was able to collect modern specimens from a 13-year-old brood, and while older, archived specimens have been used in the past, it may yield some interesting results.
“Although the data we have is limited, some of the DNA sequence data for the 13-year-old chicks is somewhat different from that of the 17-year-old chicks, indicating that there may indeed be some genetic differences in the lineage. “I doubt there is,” he said.
Researchers are also interested in the fungus as a source of new drugs, Casson added. It has been used as a traditional medicine to treat inflammation in the Maori cultures of China and New Zealand.
There are very few areas where Brood XIX and Brood XIII overlap, so it is unlikely that any area will have twice the normal number of cicadas. (With millions of cicadas emerging per square acre, that doubling would be, well, pretty intense.) Also, most people can’t tell the difference between two cicadas in adjacent areas. gender is low.
“They look the same. They sound the same. And genetically, they’re almost identical,” says Chris Simon, an evolutionary biologist at the University of Connecticut.
This is not always the case. for example, Magicada Neotredecim is a 13-year-old cicada emerging this year as part of the Illinois Brood XIX.The species is almost twice the size of Magicada Septendeculaalso occurs as part of Brood XIII, a little north of Illinois, and in Iowa and Wisconsin.
For scientists like Simon, the real opportunity lies in the less obvious. She wants to know more about how cicada chicks count their years, and has sequenced their entire genome to find out which genes or genes control whether the cicada follows her 13-year cycle or her 17-year cycle. We are trying to understand this by looking for gene groups.
“One of the most interesting things is that we thought of age classes, or nestlings, as reproductively isolated, because they have precise life cycles and adults never see each other. Because we thought there wasn’t,” Simon said. “But at the end of the day, it’s not accurate, and in some cases it’s coming out four years early, and sometimes it’s coming out four years late.”
This means that different kin can still exchange genes with each other, likely facilitating further evolution of the species.
“Once the 2013 cicada and the 17 year cicada appear in the same year, you can actually experiment with hybridization,” Simon says. The last time she had a chance to do such a job was in 2015, and before that it was in 1998.
Simon added that climate change is lengthening the cicada’s growing season underground, which may be making their timing more inaccurate. Similarly, climate change could affect its distribution, as Brood VI has become established in the Washington area in recent years, she said.
In some cases, over hundreds of thousands of years, a swarm of 17-year-old cicadas can turn into a swarm of 13-year-old cicadas.
Other scientists want to better understand how cicadas affect the plants they prey on, and how trees protect themselves from herbivores. Some studies have shown, for example, not only reduced yields in orchards inhabited by cicadas, but also reduced tree-ring growth.
But cicada emergence also has ecological benefits: thanks to the decomposition of trillions of insect bodies, it not only provides protein intake for predators, but also increases phosphorus and nitrogen for plant life. bring. A 2005 study found that cuckoos leave more offspring in the years after cicada emergence, while other birds like crows seem to fly away after emergence, adding to the ecological mystery. That’s what it means.
If you’re out during this year’s molting season and your dog or toddler happens to swallow a cicada or three, there’s no need to worry, says Maureen Tarkatel, insect collection manager at Chicago’s Field Museum. says. Cicadas do not bite or sting and are completely edible.
“It’s going to be a lot of noise, but it’s going to be a once-in-a-lifetime experience, especially for the 13-year-old and 17-year-old cicadas in Illinois,” Tarkatel said.