Vibration detection and discrimination in the masked birch caterpillar (Drepana arcuata)

Abstract

Leaf-borne vibrations are potentially important to caterpillars for communication and risk assessment. Yet, little is known about the vibratory environment of caterpillars, or how they detect and discriminate between vibrations from relevant and non-relevant sources. We measured the vibratory ‘landscape’ of the territorial masked birch caterpillar Drepana arcuata (Drepanidae), and assessed its ability to detect and respond to vibrations generated by conspecific and predatory intruders, wind and rain. Residents of leaf shelters were shown to respond to low amplitude vibrations generated by a crawling conspecific intruder, since removal of the vibrations through leaf incision prevented the resident’s response. Residents did not respond to large amplitude, low frequency disturbances caused by wind and rain alone, but did respond to approaching conspecifics under windy conditions, indicating an ability to discriminate between these sources. Residents also responded differently in the presence of vibrations generated by approaching predators (Podisus) and conspecifics. An analysis of vibration characteristics suggests that despite significant overlap between vibrations from different sources, there are differences in frequency and amplitude characteristics that caterpillars may use to discriminate between sources. Caterpillars live in a vibration-rich environment that we argue forms a prominent part of the sensory world of substrate bound holometabolous larvae.

Substrate-Borne Vibrations Induce Behavioral Responses in the Leaf-Dwelling Cerambycid, Paraglenea fortunei

“…Such freezing is presumed to be advantageous for detecting vibrations as well as visual and olfactory information necessary for recognizing conspecifics or predators. The freeze response has also been demonstrated in a territorial leafdwelling caterpillar, D. arcuata (Yack et al, 2001;Guedes et al, 2012); the caterpillars stop feeding and constructing shelters (i.e., freeze) in response to vibrations from approaching intruders and begin signaling as intruders approach (Guedes et al, 2012). Similar to caterpillars, beetles can receive vibrational information from approaching con-or heterospecifics and determine the next behavioral step, such as walking or flight for escape, preceding freeze and/or startle responses.…”

“…An increasing number of studies have shown that arthropods inhabiting plants detect approaching predators, prey, or conspecifics through substrate-borne vibrations (Ota and Č okl, 1991;Bacher et al, 1997;Djemai et al, 2001;Yack et al, 2001;Djemai et al, 2004;Castellanos and Barbosa, 2006;McNett et al, 2010;Eriksson et al, 2011;Guedes et al, 2012). Michelsen et al (1982) noted that plant stems and leaves serve as channels for transmitting and receiving vibrational information.…”

“…Such discrimination can be achieved by detecting differences in vibrational characteristics including frequency, amplitude, and temporal patterns. For example, the ability of a caterpillar (Drepana arcuata) to discriminate among vibrations allows it to respond selectively to conspecifics and predators (Guedes et al, 2012). Because responding to approaching predators or conspecific intruders is often costly (Ruxton et al, 2004), it is advantageous for insects to avoid responding to abiotic stimulation.…”

Functional Morphology and Evolutionary Diversity of Vibration Receptors in Insects

“…In crickets or tettigoniid, species-specific vibratory signals can facilitate orientation in a complex 3D habitat, like bushes, toward conspecifics (Latimer and Schatral 1983;Stiedl and Kalmring 1989;Weidemann and Keuper 1987). Holometabolous caterpillars can detect and discriminate vibratory signals occurring on leaves with so far unidentified sense organs (Guedes et al 2012).These exemplary observations show the ability of various species to locate vibrational stimuli.…”

Vibratory noise in anthropogenic habitats and its effect on prey detection in a web-building spider

“…It is known that natural sources of vibratory noise, such as those caused by rain, wind and animal songs, play important roles in modulating the aforementioned behaviours. Some organisms can discriminate between noise and 'biological' cues even when both contain overlapping spectra (Caldwell, McDaniel, & Warkentin, 2009Guedes, Matheson, Frei, Smith, & Yack, 2012). However, many other organisms are subject to vibratory noise interference.…”