The simple ears of noctuoid moths are tuned to the calls of their sympatric bat community

Hannah M. ter Hofstede*, Holger R. Goerlitz, John M. Ratcliffe, Marc W. Holderied, Annemarie Surlykke

*Corresponding author for this work

Research output: Contribution to journalArticle (Academic Journal)

20 Citations (Scopus)

Abstract

Insects with bat-detecting ears are ideal animals for investigating sensory system adaptations to predator cues. Noctuid moths have two auditory receptors (A1 and A2) sensitive to the ultrasonic echolocation calls of insectivorous bats. Larger moths are detected at greater distances by bats than smaller moths. Larger moths also have lower A1 best thresholds, allowing them to detect bats at greater distances and possibly compensating for their increased conspicuousness. Interestingly, the sound frequency at the lowest threshold is lower in larger than in smaller moths, suggesting that the relationship between threshold and size might vary across frequencies used by different bat species. Here, we demonstrate that the relationships between threshold and size in moths were only significant at some frequencies, and these frequencies differed between three locations (UK, Canada and Denmark). The relationships were more likely to be significant at call frequencies used by proportionately more bat species in the moths' specific bat community, suggesting an association between the tuning of moth ears and the cues provided by sympatric predators. Additionally, we found that the best threshold and best frequency of the less sensitive A2 receptor are also related to size, and that these relationships hold when controlling for evolutionary relationships. The slopes of best threshold versus size differ, however, such that the difference in threshold between A1 and A2 is greater for larger than for smaller moths. The shorter time from A1 to A2 excitation in smaller than in larger moths could potentially compensate for shorter absolute detection distances in smaller moths.

Original languageEnglish
Pages (from-to)3954-3962
Number of pages9
JournalJournal of Experimental Biology
Volume216
Issue number21
DOIs
Publication statusPublished - Nov 2013

Keywords

  • sensory ecology
  • constant-frequency echolocation
  • horseshoe bats
  • predator-prey interactions
  • allotonic frequency hypothesis
  • ALLOTONIC FREQUENCY HYPOTHESIS
  • LASIURUS-CINEREUS-SEMOTUS
  • INSECTIVOROUS BATS
  • ECHOLOCATION CALLS
  • FIELD IDENTIFICATION
  • HEARING
  • PREDATION
  • RECOGNITION
  • LEPIDOPTERA
  • CHIROPTERA

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