Responses of larval dragonflies to conspecific and heterospecific predator cues

Abstract

1. In cannibalistic populations, smaller individuals are subject to predation by larger conspecifics, and small individuals commonly alter their behaviour in response to cannibals. Little is known, however, about the underlying cues that trigger such responses and how the behavioural responses to conspecific cannibals differ from heterospecific predators. 2. This study tests which cues are used for the detection of conspecific predators in the larva of the dragonfly Plathemis lydia and how the behavioural response to cannibals differed from the response to heterospecific predators. 3. Individuals were exposed to chemical cues, visual cues, and a combination of both cues from conspecifics as well as no predator and heterospecific predator controls during which their activity and feeding rates were observed. 4. Individuals increased their activity, spatial movement and feeding behaviour in response to either visual or chemical cues from conspecific predators, which was opposite to responses displayed with cues from heterospecific predators. Interestingly, the responses to visual and chemical cues from conspecifics combined were weaker than to either cue in isolation and similar to the no cue control. 5. The results clearly indicate that individuals are able to use chemical and visual cues to detect even very subtle differences in phenotype of conspecific predators. 6. The opposite response in behaviour when exposed to conspecific cannibals vs. heterospecific predators suggests that the presence of cannibals will increase the mortality risk of small individuals due to heterospecific predation. This risk‐enhancement is likely to have important consequences for the dynamics of predator–prey interactions.

Predator chemical cues affect prey feeding activity differently in juveniles and adults

“…Our results are thus similar to those found for a freshwater predator-prey system, in which anuran larvae of different ages reacted differently to larval dragonfly predatory cues in terms of foraging behaviour (Peacor and Werner 2000). Although exceptions exist , other types of response to predation risk have also been found to vary with age for several prey species confronted with chemical cues from predators (Mathis et al 2003;Harvey and Brown 2004;Crumrine 2006;Ferris and Rudolf 2007;Brown et al 2011). Thus, this body of evidence suggests that the nonconsumptive effects of predators on prey need to be fully understood under consideration of the possible ontogenetic changes in prey responses to predator cues.…”

Ontogenetic Shift in Efficacy of Antipredator Mechanisms in a Top Aquatic Predator, Anax junius (Odonata: Aeshnidae)

“…In fishless aquatic ecosystems, predator–prey systems are dominated by large carnivorous invertebrates. These organisms have traditionally been classified as ‘top aquatic predators’ (Hopper 2001), and numerous studies have examined their ecology and behavior in this role (e.g., Hopper 2001; Crumrine 2006; Ferris & Rudolf 2007). For example, insects from the orders Coleoptera, Hemiptera, and Odonata possess voracious predatory species that can consume invertebrate or vertebrate prey larger than the predator itself (e.g., Brodie & Formanowicz 1983, 1987).…”

“…2006; Ferris & Rudolf 2007). The common green darner, Anax junius , is a large aeshnid, which, in its nymph stage, has traditionally been classified in this role (Crumrine 2006; Ferris & Rudolf 2007). In aquatic habitats, it is a known predator of a variety of organisms, ranging from invertebrates (Hopper 2001) to small fish (Walker 1953) and amphibian larvae (e.g., Walker 1953; Caldwell et al.…”

Nature of Predation Risk Cues in Container Systems: Mosquito Responses to Solid Residues from Predation

“…The cues by which aquatic prey perceive the risk of predation are often chemical and can originate with the predator itself (Chivers and Smith 1998, Wisenden 2000, Tollrian and Heibl 2004, Gyssels and Stoks 2006, Ferris and Rudolf 2007) or can be created by the act of predation, including alarm cues that arise when prey are damaged (Chivers and Smith 1998, Relyea 2001), and dietary cues that originate only after consumed prey are digested (Chivers and Smith 1998). Understanding the source and nature of the cues to predation is central for understanding the proximate mechanisms of adaptive behavior, and may help in understanding specificity of predator detection mechanisms, the potential costs of antipredatory behavior, and ultimately the evolutionary origin of prey responses to predators.…”