Estimating predation pressure in ecological studies: controlling bias imposed by using sentinel plasticine prey

Nimalrathna, Thilina S.; Solina, Inda Dwi; Mon, Aye Mya; Pomoim, Nirunrut; Bhadra, Sreetama; Zvereva, Elena L.; Sam, Kateřina

doi:10.1111/eea.13249

Cited by 13 publications

(10 citation statements)

References 56 publications

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“…Concerns about using plasticine models for assessing predation risk, especially for measuring invertebrate predation, have been expressed in several publications (Greenop et al, 2019;Nimalrathna et al, 2023;Vet & Dicke, 1992;, but our study experimentally demonstrates the limitations and caveats of this method. We have shown (Table 1) that the use of plasticine prey models can lead to wrong conclusions about T A B L E 1 Overview of experiments and their results.…”

Section: Discussionmentioning

confidence: 75%

“…The importance for ants of being able to pick up prey is overlooked in most studies of ant predation on sentinel prey, because experimental prey, even when alive, are usually fixed to some surface (e.g., Drozdov a et al, 2013;Nimalrathna et al, 2023). We therefore conclude that plasticine models are badly suited for quantifying invertebrate predation because, at least in some habitats, some important groups of predators do not attack plasticine models.…”

Section: Invertebrate Predationmentioning

confidence: 90%

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Predation risk estimated on live and artificial insect prey follows different patterns

Zvereva

Kozlov

2023

Ecology

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Models mimicking prey organisms are increasingly used in ecological studies, including testing fundamental ecological and evolutionary theories. The general consensus is that predation risk estimated on artificial models may not quantitatively correspond to predation pressure on live prey, but it still can be used in various comparisons. We tested whether the use of live and artificial prey reveals the same patterns of variation in predation risk. We exposed live prey (blowfly larvae and puparia) and plasticine models of blowfly puparia in two boreal forest sites, both openly and in ant‐ and bird‐exclusion treatments, and we quantified attacks by both avian and invertebrate predators. Bird attack rates were always higher on live puparia than on their plasticine models, but the magnitude of this difference declined from 8.4‐fold in early summer to 2‐fold in mid‐ and late‐summer. We attribute these changes to different responses to prey by experienced adult birds that dominate the bird communities in early summer versus explorative juvenile birds that are abundant later in the season. Invertebrate daily predation rates on maggots decreased from 56% in early summer to 28% in late summer, but invertebrate attacks on plasticine models showed no seasonal changes. Overall, invertebrate predation on maggots was 67‐fold greater than their predation on models. Observations showed that wood ants did not attack plasticine models and did not leave on them any damage marks. Estimates based on artificial prey indicate a much greater role of bird predation than invertebrate predation, while estimates based on live prey suggest the opposite pattern. Thus, using live and artificial prey may lead to different conclusions about relative importance of different predator groups in a locality. Moreover, for both avian and invertebrate predators, predation risk based on artificial and live prey shows different seasonal changes and may potentially demonstrate different spatial patterns.

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Section: Discussionmentioning

confidence: 75%

Section: Invertebrate Predationmentioning

confidence: 90%

Predation risk estimated on live and artificial insect prey follows different patterns

Zvereva

Kozlov

2023

Ecology

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“…In the case of our predator assay, clay caterpillars are certainly of lower nutritional value to birds. Although the use of clay caterpillars is widespread, the method comes with explicit biases in that the lack of chemical and behavioral cues drives the underestimation of predation rates as compared with live sentinel prey (Nimalrathna et al, 2023; Zvereva & Kozlov, 2023). Even though the intensity of predation is likely underestimated in our study, we believe this method to be as informative of predator behavior as if using real prey, acknowledging that actual predation may be at a higher rate (Lövei & Ferrante, 2017).…”

Section: Discussionmentioning

confidence: 99%

Decomposing an elevational gradient in predation by insectivorous birds

Dean,

Vázquez‐González,

Hellwitz

et al. 2024

Ecosphere

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Insectivorous birds have ecologically important effects on prey abundance, behavior, and evolution, and through top‐down control, birds indirectly reduce herbivory and promote plant growth. While several studies sought to characterize biogeographic patterns in top‐down control by birds, variation in bird predation along elevational gradients is not well characterized in terms of both its commonness and the mechanisms underlying such variation. Here, we characterized variation in bird predation along a 700‐m montane elevation gradient using artificial clay caterpillars, assessing the roles of variation in aridity, other elevational effects not associated with aridity (e.g., most notably growing season length), and bird abundance and diversity. Multivariate models revealed increasing attack rates with aridity (when controlling for the effects of elevation) and elevation (when controlling for aridity). Because aridity declines with elevation, elevational patterns were not detectable in a univariate analysis. Bird abundance (but not diversity) decreased with elevation (but not aridity) and did not provide an explanation for our results, suggesting that the underlying mechanisms were behaviorally based. We speculate that the declining abundance of insect prey with elevation and aridity leads to increased bird foraging efforts and thus the likelihood of attacking clay caterpillars. If widespread, these dynamics have important consequences for both the interpretation of predation bioassays generally and our understanding of the multivariate drivers of variation in top‐down control by predators and predation risks experienced by prey.

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“…Some predators respond similarly to live and plasticine sentinel prey (Ferrante et al, 2017), but in general, attack rates on plasticine sentinels tend to be lower (Lövei & Ferrante, 2017). Two new studies have also found artificial prey can underestimate attacks by invertebrates more severely than those by vertebrates (Nimalrathna et al, 2023; Zvereva & Kozlov, 2022). Disparities between attack rates on live prey vs. artificial sentinels can also change strongly within a season and do so inconsistently depending on the predator group in question, leading to misleading conclusions about the relative importance of various predator groups.…”

Section: Discussionmentioning

confidence: 99%