When They Hear Plants Crying, Moths Make a Decision

The discomfort of sitting next to a crying baby on an airplane may parallel how moths perceive stressed plants. When certain plants experience stress, they emit a series of ultrasonic clicks, resembling a somber melody. Remarkably, some moths can detect these sounds, and recent research indicates that these insects may use the clicks as a signal to determine suitable locations for laying their eggs. This intriguing finding was detailed in a paper published online and submitted to the journal eLife.

According to Rya Seltzer, an entomologist at Tel Aviv University and a study co-author, this discovery sheds light on the communication between plants and insects. “Plants emit sounds, and insects are really listening to that,” Seltzer noted. The research focused on the Egyptian cotton leafworm, which can hear these ultrasonic clicks, aiming to uncover whether the female leafworms rely on such sounds when deciding where to lay their eggs—a critical decision for their offspring's survival.

Initially, the team demonstrated that the female leafworms favored laying eggs on healthy plants over stressed, dehydrated ones. Following this, they conducted further experiments to investigate if the ultrasonic clicks played a role in their decision-making process. Crucial findings were revealed when moths were presented with two tomato plants—one healthy and silent, the other also healthy but emitting recorded distress sounds. The moths showed a clear preference for the quieter plant for egg-laying.

Seltzer emphasizes the need for additional research to understand how moths might integrate acoustic signals with other cues, such as scent. She posits that the phenomenon might be more widespread among various insects and plants, as many insects respond to ultrasonic sounds produced by stressed plants. “I’m putting my bet on that—it's a very wide phenomenon,” she concluded. — GENNARO TOMMA / NYT