Prey perception of predation risk: volatile chemical cues mediate non-consumptive effects of a predator on a herbivorous insect

Abstract

Predators can affect prey in two ways-by reducing their density (consumptive effects) or by changing their behavior, physiology or other phenotypic traits (non-consumptive effects). Understanding the cues and sensory modalities prey use to detect predators is critical for predicting the strength of non-consumptive effects and the outcome of predator-prey encounters. While predator-associated cues have been well studied in aquatic systems, less is known about how terrestrial prey, particularly insect larvae, detect their predators. We evaluated how Colorado potato beetle, Leptinotarsa decemlineata, larvae perceive predation risk by isolating cues from its stink bug predator, the spined soldier bug, Podisus maculiventris. When exposed to male "risk" predators that were surgically manipulated so they could hunt but not kill, beetles reduced feeding 29% compared to controls. Exposure to risk females caused an intermediate response. Beetles ate 24% less on leaves pre-exposed to predators compared to leaves never exposed to predators, indicating that tactile and visual cues are not required for the prey's response. Volatile odor cues from predators reduced beetle feeding by 10% overall, although male predators caused a stronger reduction than females. Finally, visual cues from the predator had a weak effect on beetle feeding. Because multiple cues appear to be involved in prey perception of risk, and because male and female predators have differential effects, beetle larvae likely experience tremendous variation in the information about risk from their local environment.

Ecophysiological effects of predation risk; an integration across disciplines

“…Prey organisms rely on visual, chemical, and mechanical cues from predators and, as a general rule from behavioral studies, the stronger and riskier the cue detected, the stronger the resulting antipredator response (Relyea 2003). In this issue, Hermann and Thaler (2014) show that a terrestrial beetle uses olfactory cues and other information to detect predators and that the olfactory cues differ for male and female predators. Interestingly, beetles find male predators "smellier" than females even though females are more lethal, potentially creating a disjunct between information and actual risk.…”

Behavioural responses of pine weevils to non‐consumptive interactions with red wood ants

“…The prey may respond to the presence of predators using different types of cues, for example tactile, chemical and visual cues (Rypstra & Buddle, ; Hermann & Thaler, ). Volatile chemicals produced by ants, for example have previously been shown to affect movement behaviour of spiders (Mestre, Bucher & Entling, ).…”

“…Ants are known to behave aggressively, and insects they attack either try to escape (run, fly away or drop off plants) or adopt defensive behaviour, for example retract body parts and press their body to the surface (Messina, ; Völkl, ; Majerus et al ., ). In addition to physical contact, recent research has shown that reductions in insect herbivory can be mediated through non‐consumptive effects induced by several other kinds of cues from predators, for example visual or chemical (Rypstra & Buddle, ; Hermann & Thaler, ).…”

A meta‐analysis of non‐consumptive predator effects in arthropods: the influence of organismal and environmental characteristics

“…Prey may respond to predation threat with immediate behavioral changes such as reduction in activity or feeding to become less conspicuous to predators (Bernays , Hermann and Thaler ), or with physiological changes such as altered development or growth (Hawlena et al , Thaler et al ). For example, Manduca sexta larvae alter behavior (feeding rate) and physiology (assimilation efficiency and glycogen levels) in response to predation risk.…”