Predation and noise in communication networks of neotropical katydids

Lang, Alexander; Ingeborg, Teppner; Hartbauer, Manfred; Römer, Heiner

doi:10.1017/cbo9780511610363.011

Cited by 35 publications

(42 citation statements)

References 17 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…We have chosen to study solutions for a cocktail party-like problem in an insect, where signal detection is extremely difficult, because the signal (the chirp) shares most of the frequency spectrum with the long-lasting, intense masking trill of a competing species in the same habitat, in addition to the general high acoustic background in the nocturnal rainforest (Lang et al, 2005). We would expect to find robust solutions to the masking problem in the afferent processing of sensory information in insects with their limited number of neurons available (Schmidt and Römer, 2011;Hildebrandt et al, 2015).…”

Section: Discussionmentioning

confidence: 99%

Neural Mechanisms for Acoustic Signal Detection under Strong Masking in an Insect

Kostarakos

Römer

2015

Journal of Neuroscience

View full text Add to dashboard Cite

Communication is fundamental for our understanding of behavior. In the acoustic modality, natural scenes for communication in humans and animals are often very noisy, decreasing the chances for signal detection and discrimination. We investigated the mechanisms enabling selective hearing under natural noisy conditions for auditory receptors and interneurons of an insect. In the studied katydid Mecopoda elongata species-specific calling songs (chirps) are strongly masked by signals of another species, both communicating in sympatry. The spectral properties of the two signals are similar and differ only in a small frequency band at 2 kHz present in the chirping species. Receptors sharply tuned to 2 kHz are completely unaffected by the masking signal of the other species, whereas receptors tuned to higher audio and ultrasonic frequencies show complete masking. Intracellular recordings of identified interneurons revealed two mechanisms providing response selectivity to the chirp. (1) Response selectivity is when several identified interneurons exhibit remarkably selective responses to the chirps, even at signal-to-noise ratios of Ϫ21 dB, since they are sharply tuned to 2 kHz. Their dendritic arborizations indicate selective connectivity with low-frequency receptors tuned to 2 kHz. (2) Novelty detection is when a second group of interneurons is broadly tuned but, because of strong stimulus-specific adaptation to the masker spectrum and "novelty detection" to the 2 kHz band present only in the conspecific signal, these interneurons start to respond selectively to the chirp shortly after the onset of the continuous masker. Both mechanisms provide the sensory basis for hearing at unfavorable signal-to-noise ratios.

show abstract

Section: Discussionmentioning

confidence: 99%

Neural Mechanisms for Acoustic Signal Detection under Strong Masking in an Insect

Kostarakos

Römer

2015

Journal of Neuroscience

View full text Add to dashboard Cite

show abstract

“…This species is more active and communicates mainly by singing during new moon nights. Near full moon, it moves less, avoids moonlit spots, and signals predominantly by tremulation (Lang et al 2005). Consequently, bats such as L. silvicolum searching for katydids by passive listening (Belwood 1988;Kalko et al 1999) would be much less efficient around full moon.…”

Section: Discussionmentioning

confidence: 99%

“…Singing is correlated with general activity, such as feeding, walking or flying, and should be a direct indicator of predator avoidance behavior (Lang et al 2005). Noise-levels were recorded from late October to early December 2001, as well as in February, May and June 2002.…”

Section: Katydid Activitymentioning

confidence: 99%

Activity levels of bats and katydids in relation to the lunar cycle

et al. 2005

Self Cite

View full text Add to dashboard Cite

Animals are exposed to many conflicting ecological pressures, and the effect of one may often obscure that of another. A likely example of this is the so-called ''lunar phobia'' or reduced activity of bats during full moon. The main reason for lunar phobia was thought to be that bats adjust their activity to avoid predators. However, bats can be prey, but many are carnivorous and therefore predators themselves. Thus, they are likely to be influenced by prey availability as well as predation risk. We investigated the activity patterns of the perchhunting Lophostoma silvicolum and one of its main types of prey, katydids, to assess the influence of the former during different phases of the lunar cycle on a gleaning insectivorous bat. To avoid sampling bias, we used sound recordings and two different capture methods for the katydids, as well as video monitoring and radiotelemetry for the bats. Both, bats and katydids were significantly more active during the dark periods associated with new moon compared to bright periods around the full moon. We conclude that foraging activity of L. silvicolum is probably influenced by prey availability to a large extent and argue that generally the causes of lunar phobia are species-specific.

show abstract

“…Many tropical animals use sound for communication, including various insects, such as orthopterans (crickets and katydids) and hemipterans (cicadas), as well as various nonavian vertebrates including frogs and mammals. Many insect sounds are loud, exhibit frequency overlap with some bird sounds and vary temporally with a peak at night and cessation at sunrise (Diwakar & Balakrishnan, 2007;Lang, Teppner, Hartbauer, & R€ omer, 2005). Such nonavian noise has considerable potential to interfere with avian communication at dawn but has received comparatively little study.…”

mentioning

confidence: 99%