Moths detect bat attack signals: Ultrasonic pulse rates drive distinct escape responses

For many nocturnal moths, hearing sound waves is a matter of survival in night sky. Their ability to detect ultrasonic calls emitted by bats determines whether they escape or become prey. This predator-prey relationship has shaped the behavior, physiology, and sensory systems of both groups. Echolocating bats have developed complex call patterns to track insects in flight, while moths have evolved remarkable countermeasures, including evasive flight and sound-deflection tactics. The luna moth, for instance, spins its long hindwings to deflect the ultrasonic cries of bats and avoid capture. Although there are multiple studies on the auditory escape mechanisms of moths, the species-specific behavioral responses remain unexplored. 

Against this backdrop, Professor Masashi Nomura from the Graduate School of Horticulture at Chiba University, Japan, and Dr. Ryo Nakano from the Institute for Plant Protection at the National Agriculture and Food Research Organization (NARO), Japan —who has been studying bat-moth interactions and developed ultrasonic pest control techniques (Nakano et al. 2022 PNAS)— have been investigating the long-running evolutionary contest, which they describe as a "coevolutionary arms race" between bats and moths.

A study published online in the journal Pest Management Science on September 10, 2025, by Prof. Nomura and his team, including first author Dr. Ming Siang Lem from Chiba University , sheds new light on species-specific behavioral responses of moths. The study explores how a species of noctuid moth called Autographa nigrisigna (Walker) in the subfamily Plusiinae, which is widely distributed across East and South Asia, recognizes and reacts to bat echolocation calls. Their findings could help develop ultrasonic pest management strategies in agriculture, such as reducing moth egg-laying on vegetables.

"We wanted to quantify the auditory-mediated escape mechanisms of A. nigrisigna in response to controlled ultrasonic pulses under varying pulse rate regimes to understand egg-laying and flight characteristics," say Prof. Nomura and Dr. Nakano.

A key focus of the study was how the moths reacted to the pulse repetition rate (PRR), which measures how frequently bats emit their ultrasonic pulses. These pulse patterns signal different stages of a bat's hunt. When bats are searching for prey, their calls are slow and widely spaced. As they close in, the pulses become faster, ending in a rapid burst known as the "terminal buzz," just before the capture.

To explore how moths respond to these varying signals, the team recreated bat calls in the laboratory. They exposed 100 unmated adult plusiine moths­—50 males and 50 females­—to ultrasound pulses with different PRRs: low (1, 5, and 10 Hz), intermediate (20 and 40 Hz), and high (80 and 160 Hz).

Additionally, they tested how ultrasonic cues affect reproduction-related behavior by exposing gravid (egg-bearing) females to different PRRs. The moths adjusted their flight behavior depending on the pulse rate. At lower PRRs, they made simple avoidance turns, while at higher PRRs, they flew erratically or stopped flying altogether, showing stronger responses to sounds resembling an approaching bat. Gravid females were more likely to stop flying when exposed to higher PRRs, suggesting that moths balance survival and reproduction depending on the level of perceived danger.

"Mated females of A. nigrisigna selectively avoid ultrasonic PRRs that reflect high predation risk, the same rates emitted by bats during prey pursuit. This adaptive response highlights the evolutionary balance between predator evasion and reproductive investment in nocturnal moths," says Dr. Lem.

Ultimately, this finding gives us more insight into one of nature's most enduring rivalries: the silent evolutionary battle between bats and moths that has shaped both species for more than 60 million years. "Installing the ultrasonic emitters in fields to reduce nighttime moth activity could lead to reduced pesticide use. If ultrasonic treatment works for other pest moths as well, environmentally friendly pest control may become a reality," say Prof. Nomura and Dr. Nakano.

By taking inspiration from nature's own defense mechanisms, such as echolocation, this study could lead to novel pest control strategies and support more sustainable farming.

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About Professor Masashi Nomura from Chiba University

Dr. Masashi Nomura is a Professor and Vice Dean at the Graduate School of Horticulture, Chiba University, Japan. His research focuses on environmentally friendly pest management, employing biological and physical control methods to reduce pest populations without relying solely on chemical pesticides, and integrating these approaches through Integrated Pest Management. He also studies insect molecular phylogenetics and intraspecific variation, uncovering species differentiation and cryptic species within widely distributed insects. His current interests include Wolbachia lineage replacement, ultraviolet radiation effects on beneficial insects, and genetic variation in dragonflies.

Funding:

This study was financially supported by the Agri-Net Scholarship Program under the Japan International Cooperation Agency (JICA) (Grant Number D2202241).

Reference:

Authors: Ming Siang Lem¹, Ryo Nakano², and Masashi Nomura¹

Affiliations: ¹Laboratory of Applied Entomology, Graduate School of Horticulture, Chiba

 University, Japan

²Migratory Insect Pests and Advanced Control Technology Group, Institute for Plant Protection, NARO, Japan