Are terrestrial isopods able to use stridulation and vibrational communication as forms of intra and interspecific signaling and defense strategies as insects do? A preliminary study in Armadillo officinalis

Abstract

The capability of producing sounds and vibrations is well known in insects and is thought to be a form of intra-and interspecific communication. Sounds and vibrations are used and modulated for several aims such as interacting with conspecifics, getting information from the environment, and defending against predators. This phenomenon is less known but also present in other arthropods, including a few roller-type terrestrial isopods. In this study, we used a Y-shape test apparatus to investigate the behavior of adult individuals of Armadillo officinalis Duméril, 1816 (Crustacea: Isopoda: Oniscidea) when exposed to two particular vibrational stimuli, namely species-specific stridulations and non-specific substrate-borne vibrations. Our results showed that adults of A. officinalis significantly react to the presence of both types of vibrational stimuli, by moving away from the vibrational source as if they experienced these vibrations as a sign of danger or disturbance. A. officinalis can produce stridulations only when it rolls into a ball during the so-called conglobation, a possible defense mechanism against predators. Stridulation might thus be a secondary form of defense used during conglobation to deter a predator following contact with it and might be experienced as an alert by conspecifics nearby. The high sensitivity to non-specific substrate-borne vibrations might provide A. officinalis with the possibility to anticipate dangers and adverse conditions, giving it a better chance of survival.

Biotremology in arthropods

“…We have found evidence suggesting that A. officinalis might use typical behavioral processes—that is, turn alternation (Cividini & Montesanto, 2018a , 2018b ), aggregation (Cividini & Montesanto, 2018c ), and stridulation (Cividini, Sfenthourakis, & Montesanto, 2020 )—as potential defense strategies against predators. These behavioral dynamics, mediated by substrate vibrations, might also allow individuals to anticipate and avoid disturbance and injury before encountering the sources of them.…”

“…Armadillo officinalis can produce stridulations only when it assumes the typical ball shape during conglobation, a mechanism mainly considered as a potential antipredator strategy (Caruso & Costa, 1976;Cazzolla Gatti et al, 2019;Schmalfuss, 1984;Taiti et al, 1998;Tuf et al, 2015;Witz, 1990). As with many species of insects (Kowalski, Lakes-Harlan, Lehmann, & Strauß, 2014;Masters, 1979Masters, , 1980, production of sounds during conglobation could be a secondary form of defense b a s e d o n a n a c o u s t i c w a r n i n g , a n d u s e d b y A. officinalis to deter a predator following contact (Cividini et al, 2020). For this reason, conspecifics might interpret species-specific stridulations as an alarm signal, moving away from the source of disturbance (Cividini et al, 2020).…”

“…As with many species of insects (Kowalski, Lakes-Harlan, Lehmann, & Strauß, 2014;Masters, 1979Masters, , 1980, production of sounds during conglobation could be a secondary form of defense b a s e d o n a n a c o u s t i c w a r n i n g , a n d u s e d b y A. officinalis to deter a predator following contact (Cividini et al, 2020). For this reason, conspecifics might interpret species-specific stridulations as an alarm signal, moving away from the source of disturbance (Cividini et al, 2020). The high sensitivity to nonspecific substrate-borne vibrations has been further demonstrated and might provide A. officinalis with a better chance of survival thanks to the ability to anticipate dangers and adverse conditions (Cividini et al, 2020).…”

“…The presence of substrate-borne waves might be interpreted as a source of disturbance or imminent danger, leading animals to increase turn alternation to escape from unfavorable environmental conditions (Cividini & Montesanto, 2018a , 2018b ). Thanks to its ability to produce stridulations, A. officinalis might perceive, utilize, and manage substrate-borne vibrations better than other nonstridulating species and for multiple aims (Cividini & Montesanto, 2018a , 2018b ; Cividini et al, 2020 )—for example, defense mechanisms (also through eavesdropping) and intraspecific and interspecific communication.…”

“…The graphs were created using the Signal Analyzer App in MATLAB R2018b (9.5) (The MathWorks Inc., Natick, MA, USA). From Cividini et al ( 2020 ; http://creativecommons.org/licenses/by/4.0/). (Color figure online) …”