Long before an ordinary chicken egg became an Instagram star, Jun Endo, a Ph.D. student at Kyoto University, sat gazing intently at another egg. This egg was much smaller, roughly the size of a sesame seed, and contained a stink bug.
The mystery was this: When the egg finally hatched, it would do so virtually in unison with all the other stink bug eggs clumped around it. How? What signaled an egg on one side of the brood to hatch so soon after an egg on the other side?
Synchronized hatching may be common in the animal world; scientist can’t say for sure, as the phenomenon is not well studied. Sometimes bird eggs in the same clutch hatch individually, in a series that can unfold over more than a day. The broods of some stink bug species hatch over several hours.
Mr. Endo’s brood belonged to the brown marmorated stink bug, Halyomorpha halys, which is known for wreaking havoc on farms and in suburban homes across the United States. Through a series of experiments, he attempted to identify the cue that got the eggs hatching.
“At first I had to consider every possibility — a sound, volatile chemical, vibration and pressure,” he said in an email. It was only when he played a vibration at a specific frequency, and the eggs promptly hatched, that he knew he was on the right track. Additional experiments confirmed that the vibration — brief, barely audible and recorded from a hatching stink-bug egg — signaled other eggs to follow suit.
The discovery, described in a paper in Current Biology earlier this month, resonated not only with the stink-bug researchers of the world, but also with life-science researchers focused on biotremology, the science of vibrations.
“Not many people know about it, but they should,” said Peggy Hill, a behavioral ecologist at the University of Tulsa, and author of a book called “Vibrational Communication in Animals.” In recent years, scientists have paid increasing attention to the role that vibrations play in the lives of elephants, kangaroos, crickets and many other animals.
“What makes it cool is that it’s something we can’t hear in the air,” Dr. Hill said. “But it’s an essential communication cue or signal.”
Hatching in unison is an advantage for the marmorated stink bug, said Hideharu Numata, a biologist at Kyoto University and an author of the new study. The hatched larvae won’t eat other larvae, but they will eat the unhatched, so slowpokes risk being devoured by their new siblings. Last one out is an eaten egg.
Dr. Numata has studied stink bugs for 30 years, and in that time has come to tolerate the stink. “I don’t like this smell particularly, but I feel it’s not so bad,” he said in an email. “Stink bugs sometimes smell like some fruits.”
Heather Murphy is a science reporter. She writes about the intersection of technology and our genes and how bio-tech innovations affect the way we live. @heathertal
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