Early erratic flight response of the lucerne moth to the quiet echolocation calls of distant bats

PLoS One. 2018 Aug 20;13(8):e0202679. doi: 10.1371/journal.pone.0202679. eCollection 2018.

Abstract

Nocturnal insects have evolved ultrasound-sensitive hearing in response to predation pressures from echolocating insectivorous bats. Flying tympanate moths take various evasive actions when they detect bat cries, including turning away, performing a steering/zigzagging flight and ceasing flight. In general, infrequent ultrasonic pulses with low sound intensities that are emitted by distant bats evoke slight turns, whereas frequent and loud ultrasonic pulses of nearby bats evoke erratic or rapid unpredictable changes in the flight path of a moth. Flight cessation, which is a freezing response that causes the moth to passively dive (drop) to the ground, is considered the ultimate last-ditch evasive behaviour against approaching bats where there is a high predation threat. Here, we found that the crambid moth Nomophila nearctica never performed passive dives in response to frequent and loud ultrasonic pulses of >60 dB sound pressure level (SPL) that simulated the attacking echolocation call sequence of the predominant sympatric insectivorous bat Eptesicus fuscus, but rather turned away or flew erratically, regardless of the temporal structure of the stimulus. Consequently, N. nearctica is likely to survive predation by bats by taking early evasive action even when it detects the echolocation calls of sympatric bats hunting other insects at a distance. Since aerially hawking bats can track and catch erratically flying moths after targeting their prey, this early escape strategy may be common among night-flying tympanate insects.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acoustic Stimulation
  • Animals
  • Chiroptera / physiology*
  • Echolocation / physiology
  • Escape Reaction
  • Female
  • Flight, Animal / physiology*
  • Locomotion
  • Male
  • Moths / physiology*
  • Predatory Behavior

Grants and funding

RN was supported by the Japan Society for the Promotion of Science Postdoctoral Fellowships for Research Abroad 26132 (http://www.jsps.go.jp/english/index.html) and the Council for Science, Technology and Innovation (CSTI) Cross-Ministerial Strategic Innovation Promotion Program (‘Technologies for creating next-generation agriculture, forestry and fisheries’) (http://www8.cao.go.jp/cstp/panhu/sip_english/sip_en.html). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.