Communication Dans Un Congrès Année : 2025

How many prey does a predator eat in a day?

Résumé

Very few interactions are as decisive as trophic interactions to understand the structure and dynamics of ecological communities. Initiated as such in the early days of ecological research [Elton 1927, Lindeman 1942, Odum 1968], works on food webs have recently benefited from the development of molecular analyses [Pereira et al. 2023], especially DNA-based analyses such as PCR-diagnostic or Metabarcoding. Applied to gut content or faeces indeed, molecular analyses greatly facilitate the description of food webs, and can provide novel insights on diet diversity and food references. However, despite commendable efforts [e.g. Zhang et al. 2007a], molecular analyses remain largely qualitative (presence/absence of prey) [Furlong et al. 2015]. Furthermore, molecular evidences of prey consumption decay at a different rate for each predator-prey pair, which impedes the quantification of prey consumption rates based on prey detection frequency. Previous works circumvented this issue by adjusting detection frequencies with prey DNA half-lives [Greenstone et al. 2010, Uuiterwaal et al. 2020] calibrated on voracity experiments [Greenstone et al. 2014], allowing the inference of relative consumption rates. In line with those works, we propose a Hierarchical Bayesian Model that integrates field detection frequencies and voracity data in a novel mechanistic framework to infer posterior probability distributions of key parameters encompassing possible uncertainties. By explicitely discriminating predation and digestion, the model provides an estimate of the slope and intercept of the digestion curve and an estimate of the number of preys consumed by a predator in a day, hereby referred to as predation intensity. At second order of hierarchy, moreover, each parameter is broken down into a prey, a predator and a pair effect which allows information to be leveraged from widely observed species to inform and improve estimates on rare species. Through a case study with 27 carabid beetles’ species preying on 5 types of preys in agricultural fields (wheat and beet), we use our model to investigate the main drivers of predation intensity at species scale (i.e. traits such as predator diet or size) and at community scale (i.e. characteristics such as community size or alpha diversity).

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Dates et versions

hal-05302460 , version 1 (07-10-2025)

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  • HAL Id : hal-05302460 , version 1

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Abel Louis Masson, Kévan Rastello, Marie-Pierre Etienne, Ambre Sacco--Martret de Préville, Elsa Canard, et al.. How many prey does a predator eat in a day?. 27th International Congress of Entomology (ICE2024 Kyoto), Aug 2025, Kyoto (Japan), Japan. ⟨hal-05302460⟩
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