ArticlePublisher preview available

Stridulation can suppress cannibalism in a specialised araneophagous predator

July 2018
Behavioral Ecology and Sociobiology 72(8)

DOI:10.1007/s00265-018-2541-3

Authors:

Eva Líznarová

Masaryk University

Lenka Sentenská

University of Toronto

Frantisek Stahlavsky

Charles University in Prague

Stano Pekar

Masaryk University

Acoustic signalling is widespread in arthropods and appears to be common in spiders, but the function is still unknown in many species. Acoustic signals have several functions and can be used both in interspecific (e.g., to threaten potential predators) and intraspecific (during courtship) communication. In our study, we investigated the intraspecific role of stridulation in the araneophagous Palpimanus spider (Araneae: Palpimanidae). These spiders are specialised in hunting other spiders at all ontogenetic stages. We hypothesised that stridulation is used to avoid cannibalism. We investigated the morphology of the stridulatory apparatus, analysed the acoustic signals that various stages produce, and found two types of stridulation, low- and high-intensity stridulation. Then, we investigated the presence of cannibalism between individuals of variable body size and the use of stridulation during interactions. We found that cannibalism occurred only when the prosoma size difference between the two opponents was more than 200%. Then, we paired conspecific large control Palpimanus with smaller control individual or with individual whose stridulatory organs were impaired and found that impaired spiders suffered significantly higher cannibalism than the control spiders. Our study reveals a novel role of acoustic communication in the conspecific recognition of araneophagous spiders. Significance statement Cannibalism is widespread among predatory animals. However, cannibalism might not be an optimal strategy for several reasons and should be a less preferred option for predators. Palpimanus spiders are prey specialised predators preying primarily on other spiders thus the risk of cannibalism is even higher than in generalist predators. These spiders possess stridulatory apparatus and they often stridulate following a contact with conspecifics. We found that cannibalism occasionally occurred during contact with conspecifics and that the probability of cannibalism increased with the size difference between the interacting individuals. When the spiders were not able to stridulate during contact, the probability of cannibalism increased significantly. Our results thus show that Palpimanus spiders use stridulation to reduce cannibalism among unequally sized individuals.

Interaction between two Palpimanus gibbulus individuals, an adult female (on the left) and a juvenile (on the right). Notice the extended forelegs in both individuals

…

SEM of the stridulatory apparatus of P. gibbulus. a A file on the chelicera of a juvenile. b Palpal femur of a juvenile with a plectrum (a couple of teeth marked with an arrow). c A file on the chelicera of an adult female. d Palpal femur of an adult female with a plectrum (a couple teeth marked with an arrow)

…

Time and frequency domains of sample low (a–c) and high (d–f) intensity stridulation by P. gibbulus. The sonogram (a) including two syllables, oscillogram (b), and power spectrum (c) of the first syllable are shown. Sonogram (d) including five syllables, oscillogram (e) and power spectrum (f) of the fourth syllable are shown

…

Relationship between the probability of cannibalism and the prosoma size ratio of Palpimanus spiders. Data from all trials in which unmanipulated Palpimanus spiders were used are combined. The estimated logit model is shown

…

Kinematic diagram of behaviour performed by the smaller Palpimanus individuals (58 trials). The transition probabilities between particular behavioural events are indicated by the width of the lines and by the numbers next to the lines

…

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ORIGINAL ARTICLE

Stridulation can suppress cannibalism in a specialised

araneophagous predator

Eva Líznarová

&Lenka Sentenská

&František Šťáhlavský

&Stano Pekár

Received: 31 January 2018 /Revised: 20 June 2018 /Accepted: 29 June 2018 /Published online: 10 July 2018

#Springer-Verlag GmbH Germany, part of Springer Nature 2018

Abstract

Acoustic signalling is widespread in arthropods and appears to be common in spiders, but the function is still unknown in many

species. Acoustic signals have several functions and can be used both in interspecific (e.g., to threaten potential predators) and

intraspecific (during courtship) communication. In our study, we investigated the intraspecific role of stridulation in the

araneophagous Palpimanus spider (Araneae: Palpimanidae). These spiders are specialised in hunting other spiders at all onto-

genetic stages. We hypothesised that stridulation is used to avoid cannibalism. We investigatedthe morphology of the stridulatory

apparatus, analysed the acoustic signals that various stages produce, and found two types of stridulation, low- and high-intensity

stridulation. Then, we investigated the presence of cannibalism between individuals of variable body size and the use of

stridulation during interactions. We found that cannibalism occurred only when the prosoma size difference between the two

opponents was more than 200%. Then, we paired conspecific large control Palpimanus with smaller control individual or with

individual whose stridulatory organs were impaired and found that impaired spiders suffered significantly higher cannibalism

than the control spiders. Our study reveals a novel role of acoustic communication in the conspecific recognition of

araneophagous spiders.

Significance statement

Cannibalism is widespread among predatory animals. However, cannibalism might not be an optimal strategy for several reasons

and should be a less preferred option for predators. Palpimanus spiders are prey specialised predators preying primarily on other

spiders thus the risk of cannibalism is even higher than in generalist predators. These spiders possess stridulatory apparatus and

they often stridulate following a contact with conspecifics. We found that cannibalism occasionally occurred during contact with

conspecifics and that the probability of cannibalism increased with the size difference between the interacting individuals. When

the spiders were not able to stridulate during contact, the probability of cannibalism increased significantly. Our results thus show

that Palpimanus spiders use stridulation to reduce cannibalism among unequally sized individuals.

Keywords Acoustic signal .Araneophagy .Defence .Intraspecific interaction .Predation .Spider

Introduction

Animals communicate via visual, chemical, tactile, vibratory,

and acoustic signals. Acoustic communication is widespread

and diverse not only among vertebrates but in arthropods too

(Alexander 1967); yet, the biological significance of sounds in

arthropods is often elusive (Lazzari et al. 2006; Wessel 2006).

Acoustic signals are employed in interspecific interactions,

e.g. to deter potential enemies (Alexander 1960;Masters

1979;UetzandStratton1982;Marshalletal.1995;Lazzari

et al. 2006), to locate prey (e.g. Jones 2005; Surlykke and

Kalko 2008), or in intraspecific communication, particularly

during courtship and copulation (Gwynne and Dadour 1985;

Maddison and Stratton 1988;UhlandSchmitt1996).

Communicated by J. Pruitt

Electronic supplementary material The online version of this article

(https://doi.org/10.1007/s00265-018-2541-3) contains supplementary

material, which is available to authorized users.

*Eva Líznarová

liznarovaeva@centrum.cz

Department of Botany and Zoology, Faculty of Science, Masaryk

University, Kotlářská 2, 611 37 Brno, Czech Republic

Department of Zoology, Faculty of Sciences, Charles University,

Vin ičná 7, Praha 128 43, Czech Republic

Behavioral Ecology and Sociobiology (2018) 72: 127

https://doi.org/10.1007/s00265-018-2541-3

Content courtesy of Springer Nature, terms of use apply. Rights reserved.

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