Characterizing a novel predator\u2013prey relationship between native Diplonychus esakii (Heteroptera: Belostomatidae) and invasive Gambusia affinis (Teleostei: Poeciliidae) in central China

Xu Ouyang,Martin Plath,Hong Ji,Jiancao Gao,Zaizhao Wang,Bojian Chen

doi:10.1007/s40071-017-0163-4

Abstract

A considerable body of the literature considers the potential impact of exotic predators on native prey organisms, while comparatively, few studies have asked whether and how native predators include novel prey types into their diet spectrum. Here, we asked whether the native aquatic heteropteran Diplonychus esakii preys on the highly invasive western mosquitofish (Gambusia affinis), which has been introduced to southern China and threatens native fish species through competition and predation on their fry. We conducted 48-h prey choice experiments under semi-natural conditions. In a ‘no-choice’ experiment (one predator and one potential prey; n = 200), we found the heteropterans to prey more on large-bodied fish, a pattern that was also described for other belostomatids, while prey sex had no effect on capture rates. Moreover, large-bodied heteropterans caught more fish than small-bodied individuals. However, overall capture rates in our study were low (11.5–30%) compared to studies on other belostomatids, which explains why subsequent binary prey choice experiments using one predator and two prey—either large and small females or male and female (with smaller sample sizes of n = 20 and 30, respectively)—did not confirm the results of our first experiment. Our study exemplifies how a pattern of body size-dependent predation can arise in a novel (not coevolved) predator–prey interaction. We tentatively argue that the observed pattern could be driven by intrinsic features of the predator, namely, altered prey preferences with increasing age coupled with a general preference for large-bodied prey, or changing nutritional needs at different developmental stages.

Highlights

Biological invasions challenge the conservation of native biodiversity and can have profound impacts on ecological processes and evolutionary dynamics (Gurevitch and Padilla 2004; Kistner and Dybdahl 2013; Stuart et al 2014)
In contrast to the aforementioned system involving coevolved predatory and prey species, our current study focused on a novel predator–prey relationship between the belostomatine D. esakii and their potential exotic prey, Western mosquitofish, Gambusia affinis
We conducted two types of experiments: (a) a ‘no-choice’ predation experiment used randomly assigned combinations of water bugs and mosquitofish to establish general patterns of body size- and sex-dependent predation. (b) In the latter experiment, we found large individuals to prey more on mosquitofish than small-bodied individuals; we conducted binary prey choice experiments with only large-bodied D. esakii to verify the effect of prey body size, and we tested if an effect of prey sex might become apparent in this experimental situation

Summary

Introduction

Biological invasions challenge the conservation of native biodiversity and can have profound impacts on ecological processes and evolutionary dynamics (Gurevitch and Padilla 2004; Kistner and Dybdahl 2013; Stuart et al 2014). Several studies focused on the question of whether and how invasive predators affect native prey species (Gerard et al 2014; Nunes et al 2014). Predation experiments by Błonska et al (2015) demonstrated that the Ponto–Caspian racer goby Babka gymnotrachelus preys more on the native. Plath College of Animal Science and Technology, Northwest A&F University, Yangling 712100, Shaanxi, People’s Republic of China

Methods

Results

Conclusion