Analyses of bat-avoidance responses of cabbage looper moth with a focus on ultrasonic pulse repetition rates

Abstract Behavioral responses of the cabbage looper, Trichoplusia ni (Hübner) (Lepidoptera: Noctuidae), to ultrasonic echolocation calls of insectivorous bats remain unclear for nocturnal predator–prey interactions. This study addressed ultrasonic pulse temporal characteristics that elicit escape responses from T. ni by subjecting tethered, flying moths of both sexes and host-searching mated females in particular to controlled ultrasound stimulation. By comparing moths flight response to bat call simulations with pulse-repetition rates (PRRs) ranging from 1 to 160 pulse/s, we show that ultrasonic pulses broadcast at 20 pulse/s (PRR20) are more effective in triggering T. ni evasive flight behaviors, especially for males which more frequently show flight cessation than females under tethered flight conditions. Focusing on mated females, the offspring (larvae) of which damage crops, ultrasonic pulses with PRR20 significantly reduced moth orientation towards host plants and decreased egg-laying frequency near them. These findings, provided by a quantitative assessment of T. ni response towards bat-like ultrasounds, demonstrates PRR20 as a major temporal parameter for ultrasonic pulse-induced evasive behavior in this species.