Light might suppress both types of sound‐evoked antipredator flight in moths

Abstract

Urbanization exposes wild animals to increased levels of light, affecting particularly nocturnal animals. Artificial light at night might shift the balance of predator-prey interactions, for example, of nocturnal echolocating bats and eared moths. Moths exposed to light show less last-ditch maneuvers in response to attacking close-by bats. In contrast, the extent to which negative phonotaxis, moths' first line of defense against distant bats, is affected by light is unclear. Here, we aimed to quantify the overall effect of light on both types of sound-evoked antipredator flight, last-ditch maneuvers and negative phonotaxis. We caught moths at two light traps, which were alternately equipped with loudspeakers that presented ultrasonic playbacks to simulate hunting bats. The light field was omnidirectional to attract moths equally from all directions. In contrast, the sound field was directional and thus, depending on the moth's approach direction, elicited either only negative phonotaxis, or negative phonotaxis and last-ditch maneuvers. We did not observe an effect of sound playback on the number of caught moths, suggesting that light might suppress both types of antipredator flight, as either type would have caused a decline in the number of caught moths. As control, we confirmed that our playback was able to elicit evasive flight in moths in a dark flight room. Showing no effect of a treatment, however, is difficult. We discuss potential alternative explanations for our results, and call for further studies to investigate how light interferes with animal behavior.

Bats in the spotlight : Spatiotemporal response of foraging and commuting bats to anthropogenic light at night

“…These results are consistent with previous studies corroborating the attraction-by-insects hypothesis instead of the attraction-by-artificial-light hypothesis (Rowse et al, 2018;Spoelstra et al, 2017). Moreover, artificial light reduces the efficiency of antipredator flight in moths (Hügel and Goerlitz, 2020;Wakefield et al, 2015). Pipistrelles may take advantage of the fact that moths are not able to escape around light sources and therefore increase the predation pressure, as suggested by the stronger positive phototaxis when emitting a feeding buzz.…”

“…Smaller moth species and indivuals with reduced mobility due to smaller wings are also less attracted to light (Van de Schoot et al, 2024;van Langevelde et al, 2011). Besides, moths display less antipredator behaviours when exposed to light (Hügel and Goerlitz, 2020;Wakefield et al, 2015), adding to the accessibility of insects as prey for bats. Catching larger and more vulnerable prey around light sources would be energetically beneficial for bats, but this could also results in morphometric adaptation in bats (Tomassini et al, 2014).…”

Effecten van nachtelijke verlichting op biodiversiteit: Een literatuurstudie voor beleidsondersteuning

“…Verlichting zorgt niet alleen dat er grote densiteiten aan prooien zijn voor insectivoren, maar ook dat deze makkelijker te vangen zijn. Zo verstoort licht het anti-predator gedrag (ontwijkende vluchtbewegingen) dat nachtvlinders in duisternis vertonen als reactie op vleermuizengeluiden [92][93][94][95] .…”

“…Verlichting zorgt voor gewijzigde interacties tussen vleermuizen en insecten. Niet alleen zijn insecten aangetrokken tot licht in grote densiteiten aanwezig, maar licht verstoort ok het antipredator gedrag (ontwijkende vluchtbewegingen) die nachtvlinders in duisternis vertonen als reactie op vleermuizengeluiden [92][93][94][95] .…”

Artificial light affects the foraging behavior in greater white‐toothed shrews (CROCIDURA RUSSULA)

“…The resulting light pollution affects animals of a wide range of taxa, by altering different aspects of their ecology, behavior, and physiology (Beier, 2006; Gaston et al, 2013). Examples are reported effects in daily activity and seasonal breeding patterns (Dominoni et al, 2013; Letallec et al, 2015), development and life history traits (Dananay & Benard, 2018; Van Geffen et al, 2014), movement, orientation, and migration (Cabrera‐Cruz et al, 2018; Horváth et al, 2009; Justice & Justice, 2016), predator–prey interactions (Hügel & Goerlitz, 2020), competition (so called night light niche ‐ Russ et al, 2015) and foraging behavior (Gaston et al, 2013; Horváth et al, 2009; Longcore & Rich, 2004).…”