Home Animal Scientists debunked a long-standing cicada delusion by analyzing their guts

Scientists debunked a long-standing cicada delusion by analyzing their guts

Scientists debunked a long-standing cicada delusion by analyzing their guts


There are no less than three certainties in life: dying, taxes and the periodic emergence of tens of millions of cicadas. However one large cicada uncertainty has lastly been put to relaxation — the query of whether or not the grownup bugs eat.

Periodical cicadas (Magicicada spp.) reside in varied broods throughout the jap United States. Each 13 or 17 years, relying on the brood, grownup cicadas emerge from the bottom en masse and embark on a four-to-six-week saga of mating and laying eggs on younger timber earlier than dying. When the newborn cicadas hatch, they fall to the bottom, burrow into the earth and feed on plant roots till they’re prepared for the following emergence. However there’s lengthy been a popularly accepted concept that after adults emerge, they don’t eat.

That notion may stem from cicadas’ lack of apparent chewing mouthparts, like these possessed by very hungry caterpillars, says James Hepler, a analysis entomologist on the U.S. Arid Land Agricultural Analysis Heart, a part of the U.S. Division of Agriculture, in Maricopa, Ariz.

The concept has even been perpetuated in some scientific papers, together with one revealed by a USDA scientist within the Seventies, Hepler says. That’s even though different scientists had reported seeing cicadas sticking their tubular mouthparts into plant stems, probably to entry sap. “We determined to type of settle it as soon as and for all,” he says.

A photo of a cicada resting upside down on a tree limb with leaves seen all around.
By analyzing the center of cicadas (one proven on an apple tree), researchers have lastly confirmed that the bugs do in truth feed as adults.J.R. Hepler et al/Journal of Insect Science 2023

Whereas working on the USDA’s Appalachian Fruit Analysis Station in West Virginia, Hepler and colleagues analyzed the intestine contents of 75 periodical cicadas collected from Brood X, which emerged in 2021 (SN: 12/14/21). Because the cicadas had been suspected to feed on plant sap, which is usually water and wouldn’t depart a lot of a hint of their innards, the group used a extremely delicate approach able to selecting up and decoding minuscule quantities of DNA.

Removed from discovering empty stomachs, the researchers recognized DNA from 22 sorts of plant, together with field elder, ash, oak and even hashish. On condition that “the cicadas are ingesting very minute portions of DNA,” Hepler says, “we had been pleasantly stunned that we had been capable of finding DNA in there in any respect.” The outcomes seem within the Oct. 18 Journal of Insect Science.

“It’s very nice that they really regarded on the intestine content material,” says Chris Simon, an evolutionary biologist on the College of Connecticut in Storrs who works on cicadas however wasn’t concerned within the examine. “We see them feeding,” she says, however that is “verification that they’re really ingesting these explicit issues.”

Hepler is now within the timescale of grownup feeding. “Do the cicadas transfer round from plant to plant every day, on a weekly foundation?” he asks. There’s additionally the query of what impact this mass sap-sucking has on crops. “A person cicada appears to have a comparatively low impression,” Hepler says. However when tons of of 1000’s of them descend on greenery nearly without delay, the crops face “the potential for fairly important water loss.”



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