Prey size and predator density modify impacts by natural enemies towards mosquitoes

Dalal, A., Cuthbert, R. N., Dick, J. T.A., Sentis, A., Laverty, C., Barrios‐O'Neill, D., Perea, N. O., Callaghan, A. ORCID: https://orcid.org/0000-0002-2731-3352 and Gupta, S. (2020) Prey size and predator density modify impacts by natural enemies towards mosquitoes. Ecological Entomology. pp. 423-433. ISSN 0307-6946 doi: 10.1111/een.12807

Abstract/Summary

1. Interactions between multiple predators can modify prey risk and profoundly alter ecological community dynamics. Further, ontogenic prey size changes are known to mediate prey risk through refuge effects. Understandings of these biotic factors is important for robust quantifications of natural enemy effects on target species, yet their combined influence lacks investigation. 2. Functional responses were used to quantify the predatory impacts of Notonecta glauca (water boatman; Ng) and Gammarus pulex (river shrimp; Gp) towards four different larval instars of Culex pipiens in container‐style habitats. Using conspecific pairs of predators, multiple predator effects (MPEs) of both predator species were examined across larval prey sizes, and prey preference tests were applied to examine prey selectivity across predator–prey body size ratios. 3. Both predators were able to feed on C. pipiens across their larval ontogeny; however, Ng consumed significantly more larvae than Gp. Functional responses of Ng were typically Type IIs, whereas Gp trended towards sigmoidal Type IIIs. Predation by pairs of Ng and Gp showed independent MPEs towards first‐, third‐, and fourth‐instar stages (except predation by Gp at higher densities of fourth‐instar) stages, whereas, for second‐instar stages, Ng showed synergistic MPEs and Gp showed antagonistic MPEs. Both predators preferred late instar mosquitoes (Ng: fourth instar; Gp: third instar). These preferences reflected predator:prey weight–length ratios, showing that relative sizes of predators and prey are important factors in prey selectivity. 4. The results obtained in the present study demonstrate that MPEs, combined with intraspecific prey preferences, may modulate trophic interactions within ecosystems. Therefore, such effects should be increasingly considered to further the understanding of agent efficacies.

Item Type	Article
URI	https://reading-clone.eprints-hosting.org/id/eprint/90501
Item Type	Article
Refereed	Yes
Divisions	Life Sciences > School of Biological Sciences > Ecology and Evolutionary Biology
Publisher	Wiley-Blackwell
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