Evaluation of predation risk by a caterpillar using substrate-borne vibrations

SUMMARY Substrate-borne vibration for locating mates, predators and prey is widespread in the animal kingdown. Antlion larvae dig funnel-shaped traps to catch ants and they are totally immersed in dry sand. We used a playback setup reproducing an ant walking on sand to clearly demonstrate that antlions use sand-borne vibrations to locate their prey. Half the tested animals moved towards the stimulus source. The shoot angle of sand tossing was very close to the target angle, indicating excellent ability to perceive stimulus direction. We also discuss orientation mechanisms in sand, a medium with highly unusual wave propagation properties.

Section: Introductionmentioning

confidence: 99%

Orientation towards prey in antlions: efficient use of wave propagation in sand

Fertin

Casas

2007

“…Risk assessment by frog embryos We examined information sampling by frog embryos that use substrate-borne vibrations to assess predation risk. Vibrational sensitivity is evolutionarily ancient and phylogenetically widespread (Hill, 2001), and a diverse range of prey use vibrations to cue antipredator behavior (Tautz and Markl, 1978;Bacher et al, 1997;Burger, 1998;Warkentin, 2005;Castellanos and Barbosa, 2006). Some show immediate defensive responses to vibrations, and the behaviors involved, such as ceasing to call (Lewis and Narins, 1985;Narins, 1990), freezing (Burger, 1998) or changing posture (Gnatzy and Kämper, 1990), appear low cost.…”

Section: Introductionmentioning

confidence: 99%

Flexible information sampling in vibrational assessment of predation risk by red-eyed treefrog embryos

Warkentin

Caldwell

Siok

et al. 2007

and have probably evolved multiple times. Some embryos respond to chemical cues (e.g. Chivers et al., 2001;Johnson et al., 2003) and others to vibrational cues from predators (Warkentin, 2005). These responses provide a natural context in which to examine the sensory and information-processing capacity of embryos. We examined information sampling by frog embryos that use substrate-borne vibrations to cue behaviorally mediated premature hatching.Risk assessment is critical for inducible defenses (Tollrian and Harvell, 1999) and requires that animals distinguish predator cues from benign-source stimuli (noise). This is fundamentally a signal detection problem (Bradbury and Vehrencamp, 1998;Macmillan and Creelman, 2005). For any cue property that an animal could assess, overlap is likely between the value of that property in predator cues and noise. Such overlap occurs in

“…Sound production and hearing have evolved multiple times in adult Lepidoptera (moths and butterflies), and research on the topic has contributed to the fields of neuroethology, ecology and animal behaviour (Conner, 1999;Minet and Surlykke, 2003;Yack, 2004 2001; Castellanos and Barbosa, 2006;Fletcher et al, 2006;Scott et al, 2010). Although naturalists have described the defensive sounds produced by silk and hawkmoth (Bombycoidea) caterpillars (reviewed in Brown et al, 2007), the function and mechanism of sound production in these caterpillars remain largely unknown.…”

Section: Discussionmentioning

confidence: 99%

Whistling in caterpillars (Amorpha juglandis, Bombycoidea): sound-producing mechanism and function

Bura

Rohwer

Martin

et al. 2011

SUMMARY Caterpillar defenses have been researched extensively, and, although most studies focus on visually communicated signals, little is known about the role that sounds play in defense. We report on whistling, a novel form of sound production for caterpillars and rare for insects in general. The North American walnut sphinx (Amorpha juglandis) produces whistle ‘trains’ ranging from 44 to 2060 ms in duration and comprising one to eight whistles. Sounds were categorized into three types: broadband, pure whistles and multi-harmonic plus broadband, with mean dominant frequencies at 15 kHz, 9 kHz and 22 kHz, respectively. The mechanism of sound production was determined by selectively obstructing abdominal spiracles, monitoring air flow at different spiracles using a laser vibrometer and recording body movements associated with sound production using high-speed video. Contractions of the anterior body segments always accompanied sound production, forcing air through a pair of enlarged spiracles on the eighth abdominal segment. We tested the hypothesis that sounds function in defense using simulated attacks with blunt forceps and natural attacks with an avian predator – the yellow warbler (Dendroica petechia). In simulated attacks, 94% of caterpillars responded with whistle trains that were frequently accompanied by directed thrashing but no obvious chemical defense. In predator trials, all birds readily attacked the caterpillar, eliciting whistle trains each time. Birds responded to whistling by hesitating, jumping back or diving away from the sound source. We conclude that caterpillar whistles are defensive and propose that they function specifically as acoustic ‘eye spots’ to startle predators.