Predation risk affects egg mortality and carry over effects in the larval stages in damselflies

Abstract

The non‐consumptive predator effect may incur physiological costs that affect growth and development and ultimately survival. While studies have shown that the effect can affect development and growth in organisms with complex life cycles, we have limited knowledge on the effect in the egg and early larval stage. Here, we used a laboratory experiment to examine how the presence of chemical cues, a non‐consumptive predator effect, from an aquatic predator, perch, affected hatching success of larvae in three species of damselfly, Ischnura elegans, Coenagrion pulchellum, and Enallagma cyathigerum. In addition, we examined how exposure to predation risk in the early larval stages affected growth in the late larval stages of I. elegans. We found that the presence of chemical predator cues (1) increased egg mortality in all three species, (2) caused earlier hatching of eggs in one species, no change in a second species and a delay in egg hatching in a third species. We also found that predator cues have the potential to cause a carryover effect from early larval stages to late larval stages in terms of larval growth rate. The addition of non‐consumptive predator cues in the form of fish water caused higher algal growth than in the control experimental containers, and we suggest that this algal growth has the potential to confound predator stress cues. Our results show that the non‐consumptive predator effects affect survival and growth, and hence they have the potential to affect predator–prey dynamics in natural systems. Future studies on such effects in aquatic systems should consider confounding stressors, such as algae, fungi, oxygen, and nutrients levels, that might come with the addition of predation cues in water and thus add additional stress.

Effects of predator cues carry over from egg and larval stage to adult life-history traits in a damselfly

“…For example, Baranowski and Preisser (2018) found that the non-consumptive exposure of luna moth larvae to predatory wasps resulted in increased luna moth mortality, McCauley et al (2011) showed a strong nonconsumptive lethal effect of fishes or predatory insects on dragonfly larvae, and Ower and Juliano (2019) showed that presence of chemical cues of the predacious elephant mosquito decreased eastern tree hole mosquito survivorship until emergence. Short-term behavioral and life-history studies often show that organisms are affected by fish cues (Silberbush et al 2019, Sniegula et al 2019a), but other studies have shown that the effects on behavior and growth decline over the long term (Dalesman et al 2015). Here, we showed that the effects of fish cues experienced during either or both egg and larval stages persisted until emergence because survival up to emergence was reduced, suggesting that the non-consumptive effects come with high costs in terms of mortality.…”

“…We caught adult I. elegans females at Płaszów Pond, Poland (50702 0 26 00 N, 19758 0 15 00 E) on 20 July 2018 using standard methods (Sniegula et al 2019a). The species has an aquatic egg and larval stage followed by a terrestrial adult stage.…”

“…The species has an aquatic egg and larval stage followed by a terrestrial adult stage. Eggs and larvae commonly share habitat with fishes (Corbet 1999, Le Gall et al 2017, Sniegula et al 2019a. Fishes present at Płaszów Pond include European Perch (Perca fluviatilis Linnaeus, 1758).…”

“…To provide constant predatory cues for the perch treatment groups (Van Buskirk et al 2014, Sniegula et al 2019a, every other day we replaced ¼ of the water in the experimental containers holding damselfly eggs and larvae with water from an aquarium (55 Â 35 Â 45 cm) holding 3 perch (age 11 y). In the control group, we replaced the same amount of water with aged tap water (Fig.…”

“…However, few studies have focused on how predation risk during the egg stage affects the later larval and adult stages and whether a switch from high predation risk to low predation risk over ontogeny can be compensated for in later ontogenetic stages. Nevertheless, prey can detect predator cues in the egg stage and show earlier or later hatching in response to predation risk during this stage (Warkentin 1995, 2011, Moore et al 1996, Sniegula et al 2019a.…”