“Science”, a prominent scientific research journal, published a collaborative study on periodic cicada emergence events, featuring Georgetown University biology professor Martha Weiss and George Washington University biology professor John Lill, Oct. 19.
The study comes after the Brood X cicada resurgence in May 2021 and explores the effects of cicadas on other species in forest ecosystems. The study also includes an elementary school curriculum that brings this knowledge to the next generation.
Weiss said her work for the study involved taking a deeper look at the impact on the food web that cicadas cause through their presence in the environment.
“Step one is that the birds were eating cicadas. Step two is that the birds really decreased in their biting of caterpillars. Step three is the caterpillar numbers are increasing, and the next question is: what is happening to the trees?” Weiss told the Hoya.
Weiss said the 13 or 17-year life cycles of cicadas cause intense ramifications throughout the food chain, significantly benefiting the generalist species who are able to adapt their diet to eat the cicadas, along with the prey that are spared as a result of the giant influx. The trees, however, experience twice as much damage as noncicada years due to the lack of regulation of those prey herbivores.
“There was really significant damage to the oak trees, and even though our trees were young and not yet sexually mature in terms of producing acorns, the amount of damage that we have recorded has been reported to be sufficient to impact acorn production,” Weiss said.
The team found that the trends of local cicada-feasting birds gives insight into broader ecosystem implications of their continued population decline.
“Birds are a really important regulator of insect herbivores and the amount of damage that plants receive. Over the last several decades, there’s been a significant decline in bird populations,” Lill said in a recent press release from the Earth Commons. “Our study provides a glimpse of what a world with fewer birds might look like. That would include increased damage to both forestry and agricultural crops, which has consequences for productivity and the economy.”
Weiss said she hopes to create a narrative of insects that spans beyond just pests, emphasizing how they provide integral ecosystem services to the human population, such as pollination.
“Insects are very important: they are everywhere. We don’t often notice them except the mosquitos that bite our ankles, the ants that crawl into our kitchens and bathrooms in the winter or the cockroaches that scooter across our dorm rooms every once in a while,” Weiss said.
Weiss said she and the team are looking to change the attitudes surrounding insects by spreading the story of the incredibly unusual life of periodical cicadas, which emerge from a hibernation-like state underground every 13 to 17 years.
Weiss said during their time underground, cicadas live only off of a diluted, not especially nutritious, liquid diet using their hypodermic needle-like mouths to suck water out of a plant’s roots. In the spring, when the temperature of the soil reaches exactly 64 degrees, they emerge by the billions. They then mate, lay eggs and die, leaving the new generation to burrow down into the soil for another 13 or 17 years, according to Weiss.
“Because they all come out at once in such great numbers, they overwhelm all of the predators and everybody eats until they can’t eat another cicada,” Weiss said.
In addition to the publication of the research in “Science”, Weiss and Lill are bringing this exploration to the elementary school classroom in a wide variety of forms. The team produced workbooks and follow-along videos for the students to be able to engage with the material. Additional creative elements such as a Haiku contest, which garnered over 800 entries across the area, were a success according to Diane Lill, director of education at Conservation Nation and collaborator on the project.
“We saw the Brood X emergence as an opportunity to replace fear with fascination. So many children are taught to be afraid of insects, and they miss the chance to develop empathy and curiosity about the natural world.” Lill told the Hoya. “We made the curriculum fun by including many subject areas such as math, history, music and language arts in addition to science.”
Weiss and Lill found inspiration in their own young children, who plagued them with questions in the last cicada emergence in Washington, D.C., in 2004.
“We felt that this was an opportunity to show an entire generation of kids, who are going to be growing up in this emergence when they are in elementary school, that insects were cool and exciting rather than icky and scary,” Weiss said. “We felt that it was almost entomological malpractice to not help tip the scales.”
There are populations of periodical cicadas all over the eastern United States, meaning that each year presents new learning opportunities. The team will continue this educational program in Chicago, where the next emergence is scheduled to occur in spring 2024.
“We are going to be following up on some of the questions we have been asking but with a different generalist predator: we are going to be looking at how cicadas impact the ecosystem services provided not by birds, but by ants, who are super important ecosystem service providers in our forests.” Weiss said.