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.

Abstract Predation pressure is natural selection acting on the prey. To ascertain whether prey evolve strategies to avoid predator attacks, experimental evolution was conducted using the red flour beetle, Tribolium castaneum herbst (Coleoptera: Tenebrionidae), and the adults of assassin bug, Amphibolus venator klug (Hemiptera: Reduviidae), as the model prey and predator, respectively. In this study, we compared two predator avoidance behaviors in strains of T. castatneum that were housed with (= Treatment) and without (= Control) predators for five generations. The results of the experimental evolutions showed no differences in activity levels. While significant difference in death-feigning duration between the two strains was observed; that is, the strains cohabiting with the predator showed significantly longer duration of death feigning at the five than the first generation in the strains not cohabiting with the predator. Therefore, our results suggest for the first time that death-feigning duration changes longer when exposed to predation pressure over successive generations under predation pressure. The reasons for the changes in traits across generations observed in this study are discussed.