When the “magic cicadas” sing, the caterpillars feed on themselves, and the oaks suffer

In a close-up, a winged insect on a long leaf and this caption: “Cicadas swarming”. But it’s not just any cicada. science He devotes the first page of his October 20 edition to the magazine Cicada (Magicicada Septuagint), Which only appears every seventeen years and emerged from the ground in the United States for the last time in 2021.

“Their mass emergence upsets the balance of the food chain.” We can read under the title. This is what explains A new study was published online on October 19 On the American Scientific Journal website. The researchers found that during the emergence of “resource brood,” the dynamics of forest food webs were dramatically modified.

Since 2004, during the previous appearance of magicada sevendisim, John Lyell, a biologist at the University of Washington, has observed the cascading ecological impacts of these insects. So he had seventeen years to develop an experimental method that would allow him to measure it.

During the few weeks that these plump insects congregate, they provide an all-you-can-eat buffet for birds, mammals and other predators who forgo their usual meals. Thus birds, in particular, ignore their usual prey, which are caterpillars. They are then free to gorge themselves on oak leaves.

Two years ago, the team led by John Lyell observed more than twice as many caterpillars during the periodic cicada season, and these caterpillars were causing twice as much tree and foliage damage as normal. These effects are short-lived and trees recover quickly. But other studies More lasting effects reported. Research on tree rings shows that oak trees grow slower in years when cicada brood emerges.

The study’s first author, entomologist Zoe Getman-Pickering, hopes In a general article, This work will serve as a reminder of how interconnected ecosystems are and that the shocks they experience can have far-reaching consequences.