Landscape of fear in rice paddies: effect of bat ultrasounds on the egg production of a tympanate moth pest.

Background: Predator-prey interactions are major drivers of species coevolution. Insectivorous bats emit ultrasonic pulses to orientate themselves and to pursue prey in flight. Several nocturnal lepidopterans have developed auditory organs that allow them to detect echolocating bats and change their normal behaviour to reduce predation risk, a phenomenon included within the 'landscape of fear' concept. In this study, we assessed whether bat ultrasounds affect the egg production of the tympanate moth species Chilo suppressalis, one of the most widespread rice pests in the world.

Results: Adults of C. suppressalis were captured in rice fields in Spain and kept in captivity in the presence and absence of artificially broadcasted bat ultrasounds. While no differences were found regarding the number of clutches laid per female, the clutch size was substantially smaller in the presence of bat ultrasounds (generalised linear mixed model, P value <0.05), observing a reduction in the number of eggs of up to 46%. This decrease in egg production may result from delays in adult mating or the inhibition or interruption of oviposition in females, which would alter their normal conduct to minimise their exposure to potential bat predators.

Conclusion: These findings suggest that the acoustic dimension may have profound implications for farmers because reducing the reproductive success of C. suppressalis could also lead to a significant decline in crop damage and yield loss, thereby increasing farmers' economic savings. Promoting stable bat populations in agrosystems can be highly beneficial since, in addition to suppressing harmful insects by predation, they likely reduce pest levels simply by emitting ultrasounds into the environment. © 2025 Society of Chemical Industry.