Moths can detect the ultrasounds emitted by predatory bats and have evolved ultrasound-triggered escape behaviours to avoid predation. Now, Ryo Nakano from the National Agriculture and Food Research Organization, Japan, and colleagues have developed a behavioural regulation technique using synthetic ultrasounds to suppress the intrusion of Spodoptera moths into crop fields. Nakano and colleagues generate pulsed ultrasonic white noise using a synthetic ultrasound emitter. The team determined the hearing thresholds, specified the pulse duration and repetition rate, and identified the sound pressure levels that elicit a flight-stopping response in moths. The indoor flight-tunnel experiments demonstrate that the synthetic ultrasounds can suppress the orientations of mated S. litura, S. exigua and S. frugiperda females toward host plants. The strawberry and onion field tests with a custom-made ultrasound generator show that the number of egg masses was decreased due to the synthetic ultrasound, which suppresses the flight of mated female moths into the fields but does not affect the pollination efficacy of honey bees.
Agricultural pest control has historically mainly relied on synthetic insecticides. However, safe, inexpensive, and easy-to-use alternative pest management technologies are needed to mitigate the negative impact of insecticides and reduce their cost. Using ultrasound for pest control is not a new concept, but it has not been considered suitable in large open fields. Here, with improved ultrasound emitters that can efficiently propagate ultrasounds, Nakano and the team have developed a useful technique for preventing moth pests from flying into agricultural farms, thus contributing to sustainable agriculture.
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