Selective Predation Research Articles

False Exclusion: A Case to Embed Predator Performance in Classical Population Models.

We argue that predator-prey dynamics, a cornerstone of ecology, can be driven by insufficiently explored aspects of predator performance that are inherently prey dependent: that is, these have been falsely excluded. Classical (Lotka-Volterra-based) models tend to consider only prey-dependent ingestion rate. We highlight three other prey-dependent responses and provide empirically derived functions to describe them. These functions introduce neglected nonlinearities and threshold behaviors into dynamic models, leading to unexpected outcomes: specifically, as prey abundance increases predators (1) become less efficient at using prey; (2) initially allocate resources toward survival and then allocate resources toward reproduction; and (3) are less likely to die. Based on experiments using model zooplankton, we explore the consequences of including these functions in the classical structure and show that they alter qualitative and quantitative dynamics of an empirically informed generic predator-prey model. Through bifurcation analysis, our revised structure predicts (1) predator extinctions, where the classical structure allows persistence; (2) predator survival, where the classical structure drives predators toward extinction; and (3) greater stability through smaller amplitude of cycles, relative to the classical structure. Then, by exploring parameter space, we show how these responses alter predictions of predator-prey stability and competition between predators. In light of our results, we suggest that classical assumptions about predator responses to prey abundance should be reevaluated.

Selective insecticides secure natural enemies action in cotton pest management

Cotton hosts a variety of arthropod pests requiring intensive control mostly with insecticides, which in turn may impact beneficial insects and the environment. Therefore, insect control in cotton fields preconizes the use of selective insecticides that offer pest control but conserve natural enemies. In this work, we measured the impact of recommended insecticides on the abundance of predatory insects and predation upon sentinel preys in the field. Further, the survival of four key selected predatory insects of cotton ecosystem, representing chewing and sucking feeding habits and different pest species attacked [Chrysoperla externa Hagen, Eriopis connexa (Germar), Podisus nigrispinus (Dallas) and Orius insidiosus (Say)], were assessed when exposed to the dried residues of the tested insecticides. Mortality of sentinel prey caused by natural enemies was higher in areas treated with selective insecticides relative to the non-selective ones, and most of time similar to the untreated areas. Furthermore, areas treated with non-selective insecticides experienced prolonged impact between sprays depending on the insecticide applied. Seasonal abundance of predatory insects was 2× greater in fields under selective and untreated fields compared to those under non-selective recommendation. Survival of predators exposed to the dried residues of the selective insecticides pymetrozine, chlorantraniliprole, pyriproxyfen, and cyantraniliprole were greater than when exposed to the non-selective lambda-cyhalothrin, malathion, dimethoate, and thiamethoxam. Among the non-selective insecticides, malathion and dimethoate exhibited shorter residual time compared to the thiamethoxam and lambda-cyhalothrin + thiamethoxam. Therefore, the recommendation of selective insecticides provides benefits for cotton pest management by maintaining the action of the natural enemies present in the field.

Bacterial and Archaeal Specific-Predation in the North Atlantic Basin

Stable isotope probing (SIP) was used to track prokaryotic and eukaryotic carbon uptake along a meridional transect (Long. 52˚W) in the North Atlantic to assess if 13C-resource partitioning between bacteria and archaea and 13C-labeled eukaryotic predators could be detected. One-liter SIP microcosms were amended with 13C-acetate or 13C-urea and incubated for 48 hours. Our data indicated archaea often outcompeted bacteria for 13C-urea while both archaea and bacteria could incorporate 13C-acetate. This 13C label could also be tracked into eukaryotic microbes. The largest number of 13C-labeled eukaryotic OTUs, and the greatest percentage of eukaryotic 13C signal, were observed in conjunction with both archaeal and bacterial 13C incorporation, suggesting that most eukaryotic predators do not distinguish between archaeal and bacterial prey. However, other 13C-eukaryotic OTUs were exclusively associated with either 13C-archaeal or 13C-bacterial OTUs. These archaeal-specific and bacterial-specific 13C-eukaryotic OTUs were related to known bactivorous predators including Ancyromonas, Amastigomonas, Cafeteria, and Caecitellus. Our SIP findings suggest both resource partitioning between bacteria and TACK (Thaumarchaeota, Aigarchaeota, Crenarchaeota, and Korearechaeota) archaea and selective predation by eukaryotic predators. Determining the equalizing mechanisms for co-existence in the marine environment can help map predator/prey interactions to better estimate carbon flow in the deep ocean.

Planktivorous fish positively select Daphnia bearing advanced embryos

The top-down effect of fish predation on reproduction success of Daphnia females was investigated in an outdoor mesocosm experiment with natural (oligotrophic) food conditions. The planktivorous fish, sunbleak (Leucaspius delineatus, 4.9 individuals m–3) was introduced into a half of mesocosms after the first sampling of zooplankton to compare daphnid life-history traits with and without fish predators. Our results showed selective fish predation on the daphnid females with advanced developmental stages of embryos. The Daphnia populations exposed to fish exhibited a lower proportion of females with advanced embryos over those with earlier embryonal stages. Fish predators obviously were attracted to more visible females bearing larger embryos, with well-developed pigmented eyes. Simultaneously, we found a smaller daphnid body length in the mesocosms with fish than in those that were fishless. However, the daphnid clutch size did not reflect their body-length pattern and, surprisingly, decreased regardless of fish presence or absence since the first sampling day, probably owing to deterioration of food quality (mean seston carbon:phosphorus ratio ~238). Nevertheless, this selective elimination of the females with advanced embryos, together with the overall decrease in daphnid fitness, can strengthen the deceleration of its population growth under fish predation.

Phenotypic selection by kelp gulls against pear-shaped shells of the Antarctic limpet Nacella concinna

Abstract The Antarctic limpet (Nacella concinna) presents two ecotypes related to different water depths: littoral individuals have a robust and taller shell while sublittoral individuals are thinner and flatter. Among the environmental factors possibly causing this divergence, avian predation upon littoral individuals has been mooted but has received little research attention. The kelp gull (Larus dominicanus) is the principal consumer of littoral limpets in the study area. We used shells from littoral and sublittoral zones, and from gull middens to examine – through linear morphometrics and elliptic Fourier analysis – whether selective predation exists, and to evaluate the mode of selection that could be operating on different traits. We found that limpet individuals with the apex displaced towards the anterior side were more likely to be predated. However, a remarkable result was that gulls select dorsal pear-shaped rather than elliptical shells and that there is a directional selection against pear-shaped limpets. However, in contrast to previous studies, we did not find that the proportions of elliptical or pear-shaped individuals differed between the littoral and sublittoral zones. This discrepancy could be related to variations in predatory intensity in different locations. These results suggest that where gulls have a strong influence, their effect could be a key factor in dorsal differentiation in limpet shells.

Dynamic of a Delayed Predator-Prey Model with Application to Network\u2019 Users\u2019 Data Forwarding

In most situations where entities interact by sharing limited resources, controlling populations’ density is crucial to maintain ecosystem sustainability. This is the case in a predator-prey type interaction when predator survival relies on its ability to harvest and consume resources. In this article, we analyzed a modified predator-prey model based on Rosenzweig-MacArthur characterized by a delayed conversion of prey into resources and applied the proposed model to network users’ data forwarding at a bottleneck node. We discuss system fixed points behaviour and prove that delaying the handling time has a significant impact on the dynamic of interaction and system bifurcates, exhibits chaotic behaviour and is highly responsive to small perturbations.

CONCH FRITTERS THROUGH TIME: HUMAN PREDATION AND POPULATION DEMOGRAPHICS OF LOBATUS GIGAS ON SAN SALVADOR ISLAND, THE BAHAMAS

ABSTRACTLobatus gigas, the queen conch, is a central component of Caribbean cuisine but over-fishing of juveniles has threatened the stability of wild populations. Strombid gastropods, upon reaching sexual maturity, cease growing along the shell length axis and continue growing in width via a flared and thickened shell lip. This morphology serves as a useful indicator of an individual's sexual maturity. Here we examine temporal trends in population demographics, size, and morphology of harvested L. gigas individuals over the last ∼1 ky from San Salvador Island, the Bahamas to quantify the dynamics of human-induced stress on the local queen conch fishery. We collected 284 human-harvested individuals from shell middens at seven localities, measured seven morphological variables, and classified the specimens as either adult or juvenile. We randomly selected 64 of these shells for rapid AMS radiocarbon dating in order to establish three geochronological bins: Lucayan (Pre-European invasion, 1492 CE), Modern (∼102 y), and Global (∼101 y). The proportion of juveniles harvested increased significantly from 47% (Lucayan) to 61% (Modern) to 68% (Global) suggesting increasing pressure on the fishery through time. Patterns in body size and morphology diverge between adults and juveniles and are likely the result of an increase in the proportion of harvested juveniles, the selection of smaller juveniles through time, and possibly changes in fishing methods. This size selective predation did not result in the suppression of adult body size as found in other studies. Geohistorical data, such as these, are vital for providing long term ecological context for addressing anthropogenic ecological degradation and are central to the conservation paleobiology approach.

Phage-Resistant Phase-Variant Sub-populations Mediate Herd Immunity Against Bacteriophage Invasion of Bacterial Meta-Populations.

Hypermutable loci are widespread in bacteria as mechanisms for rapid generation of phenotypic diversity within a population that enables survival of fluctuating, often antagonistic, selection pressures. Localized hypermutation can mediate phase variation and enable survival of bacteriophage predation due to high frequency, reversible alterations in the expression of phage receptors. As phase variation can also generate population-to-population heterogeneity, we hypothesized that this phenomenon may facilitate survival of spatially-separated bacterial populations from phage invasion in a manner analogous to herd immunity to infectious diseases in human populations. The lic2A gene of Haemophilus influenzae is subject to “ON” and “OFF” switches in expression mediated by mutations in a 5′CAAT repeat tract present within the reading frame. The enzyme encoded by lic2A mediates addition of a galactose moiety of the lipopolysaccharide. This moiety is required for attachment of the HP1C1 phage such that the ON state of the lic2A gene is associated with HP1c1 susceptibility while the OFF state is resistant to infection. We developed an “oscillating prey assay” to examine phage spread through a series of sub-populations of Haemophilus influenzae whose phage receptor is in an ON or OFF state. Phage extinction was frequently observed when the proportion of phage-resistant sub-populations exceeded 34%. In silico modeling indicated that phage extinction was interdependent on phage loss during transfer between sub-populations and the frequency of resistant sub-populations. In a fixed-area oscillating prey assay, heterogeneity in phage resistance was observed to generate vast differences in phage densities across a meta-population of multiple bacterial sub-populations resulting in protective quarantining of some sub-populations from phage attack. We conclude that phase-variable hypermutable loci produce bacterial “herd immunity” with resistant intermediary-populations acting as a barricade to reduce the viral load faced by phage-susceptible sub-populations. This paradigm of meta-population protection is applicable to evolution of hypermutable loci in multiple bacteria-phage and host-pathogen interactions.

First record of body colour polymorphism in giant African snail Achatina fulica (Bowdich, 1822) - a comparative study using mitochondrial cytochrome oxidase subunit I (COI) gene

The presence of the body colour polymorphism in the tropical invasive pest giant African snail is reported for the first time from South India. Three different body colour polymorphs were recognised viz. grey, black and white. The grey body colour is the most common polymorph. The black and white colour polymorphs are found to be in almost equal proportions in the reported localities with the grey counterparts. The cytochrome oxidase subunit I (COI) sequences of the three colour polymorphs are found to be identical. The presence of the body colour polymorphism in south India may be attributed to the avian predation and other selection pressures.

Cultural selection and human food preferences

Genes and culture co-evolve to determine variations in dietary habits. Our evolutionary heritage regarding food choice and food preferences is responsible for the mismatch with the food environments we have created, which leads to problems such as overweight and obesity. Several hypotheses have attempted to explain the high rate of obesity present in today’s world. The thrifty genotype hypothesis suggested that obesity today is a throwback to our ancestors having undergone positive selection for genes that favored energy storage. The drifty genotype hypothesis contends that the prevalence of thrifty genes is not a result of positive selection for energy-storage genes but, rather, is attributable to genetic drift resulting from the removal of predatory selection pressures. Both hypotheses focus on environmental changes over time, positive selection and genetic drift. While genetics plays a significant role, we believe that cultural selection is also responsible for the spread of obesogenic phenomena in Albania. The high rates of overweight and obesity among Albanians today can be explained as a mismatch between our evolutionary past and maladaptive behaviors.

Phytoseiid mites prey effectively on thrips eggs: Evidence from predation trials and molecular analyses

It is generally assumed that predation by phytoseiid mites (Acarina: Phytoseiidae) on thrips is mainly limited to the first and, to a lesser extent, the second thrips instars. Thrips eggs are imbedded in plant tissue and are supposed to be out of reach of most predators. Using a dual approach combining feeding trials with molecular gut content analysis, we confirmed that eggs of the western flower thrips, Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae), can be vulnerable to attack by a subset of phytoseiid species. Of the five species investigated, the generalist predators Amblyseius largoensis and Amblyseius swirskii were shown to most readily feed on thrips eggs, followed by Neoseiulus californicus, which is classified as a selective predator of tetranychid mites. Neoseiulus longispinosus and Proprioseiopsis lenis did not or very rarely consume thrips eggs. As substantial reductions of hatching (up to 30%) were observed, predation on eggs should not be ignored when assessing the efficacy of phytoseiids as biological control agents against thrips.

Spatiotemporal dynamics of predators and survival of marine fish early life stages: Atlantic cod (Gadus morhua) in the North Sea

Predation is one of the principle factors regulating the survival of early-life stages and recruitment success of marine fishes. Although challenging, it is important to understand how predation mortality varies in space and how this spatial variability affects the temporal dynamics of fish recruitment. We investigated the spatiotemporal variability in the magnitude of predation mortality and survival of Atlantic cod (Gadus morhua) in the North Sea by combining a Lagrangian individual-based model of cod early-life stages (eggs, larvae and age-0 juveniles) with an Eulerian representation of its fish predators based on field data collected quarterly from 1991 to 1997. The mean and variance (spatial and inter-annual) in survival of cod were different between simulations using homogeneous and heterogeneous spatial distributions of predators. Survival of cod through its early-life period was 1 order of magnitude higher in simulations using heterogeneous versus homogenous predator distributions, mainly due to reduced mortality of eggs and larvae in the former simulation. Our model predicted markedly different year-to-year changes in cod survival, when heterogeneous predator fields were implemented. In the heterogeneous simulation, Atlantic herring (Clupea harengus) and grey gurnard (Eutrigla gurnadus) emerged as the most important predators comprising, respectively, 68% and 13% of the predation mortality caused by 7 predators included in our study. A low (<0.1%) survival was predicted for cod progeny originating from known spawning grounds in the central and south-eastern North Sea while considerably higher survival (between 0.8 and 1%) was predicted for northern spawning areas and in the Southern Bight. Numerical sensitivity experiments indicated that seasonal and annual changes in the spatial distribution of predators were more important to the inter-annual variability in the modelled cod survival (52% of the mean survival) than annual changes in the biomass of predators (23%) and the variability of the North Sea hydrography (19%) with the relative importance of these factors depending on the life stage of cod. We argue that including spatial dynamics of predators will advance the predictive capacity of fish early-life stage models enabling more robust, science-based advice for spatially-explicit fishery management and marine spatial planning.

Trait‐mediated foraging drives patterns of selective predation by native and invasive coral‐reef fishes

AbstractAs the geographic ranges of species are increasingly altered by forces such as biological invasion and climate change, when and where will strong biotic interactions arise within reassembling communities? Prey selectivity data are often of limited use for predicting future consumptive interactions because they are specific to the identity and relative abundance of species in past assemblages. Here, we investigate whether the strength of consumptive interactions can be predicted based on a priori knowledge of behavioral traits that are hypothesized to affect the predation process and recur across species. To test this approach, we conducted multi‐species foraging trials with coral‐reef fishes in the Bahamas, a diverse, trait‐rich fauna for which interactions are likely shifting rapidly due to the introduction of predatory Indo‐Pacific lionfish. We evaluated predictions about the combined effects of three behavioral traits—water column position of both predator and prey, anti‐predator aggregation behavior of prey, and hunting strategy of predators—on successive phases of the predation process and ultimately the strength of predator–prey interactions. Tracking predator and prey behaviors revealed that inter‐specific variation in traits mediated relative encounter, attack, and capture rates between different predators and prey. Behaviorally driven bottlenecks at different stages of the process underpinned selective consumption by each predator species, resulting in large differences in total mortality rates among prey species. Our analysis also suggests that unique behaviors exhibited by invasive lionfish, rather than naïve responses by prey, mediate their high foraging success relative to native predators. Our results illustrate how incorporating a priori knowledge about foraging and anti‐predator traits can improve predictions of the strength of emergent consumptive interactions caused by global change.

The Impact of Selective Predation on Host-Parasite SIS Dynamics.

While models of host-parasite interactions are widespread in the theoretical literature, we still have limited understanding of the impact of community dynamics on infectious disease dynamics. When the wider host ecology is taken into account, the underlying inter-species feedbacks can lead to counter-intuitive results. For example, the 'healthy herd' hypothesis posits that the removal of a predator species may not be beneficial for a prey population infected by an endemic disease. In this work, we focus on the effects of including a predator species in a susceptible-infected-susceptible model. Specifically, a key role is played by predator selectivity for either healthy or infected prey. We explored both cases and found important differences in the asymptotic behaviours of the system. Independently from selectivity, large portions of parameter space allow for the coexistence of the three species. However, when predators feed mainly on susceptible prey we find that a fold bifurcation can occur, leading to a region of bi-stability between coexistence and parasite extinction. Conversely, when predator selection is strongly towards infected prey, total prey population density can be maximal when the three species coexist, consistent with the 'healthy herd' hypothesis. Our work further highlights the importance of community interactions to infectious disease dynamics.

Bistability and Bifurcations in Modified Nicholson-Bailey Model with Age-Structure for Prey

The paper investigates dynamic modes of the predator-prey model with age structure for prey. We use a slight modification of the Nicholson-Bailey model to describe the interaction between predator and prey. We assume the population size is regulated by decreasing juvenile survival rate with growth of age class sizes. Conditions for sustainable coexistence of interacting species are described. It is shown that the coexistence of species becomes possible if there are a transcritical or saddle-node (tangential) bifurcations. Due to the saddle-node bifurcation there is bistability in the system of interacting species: predator either coexists with prey or dies depending on the initial conditions. It is shown that the range of demographic parameters, for which the prey and predator coexist, can significantly increase with growth of survival of adult prey or the proportion of predators born or the prey consumption rate of the predator. We studied the oscillation scenarios of interacting population, influences of reproduction, survival and self-regulation rates of population prey and age-dependent predation as well as variations in the current number on transitions between different dynamic modes. It is shown that an increase in the birth rate of the prey under intraspecific competition can lead to a dynamics destabilization and to oscillations appearance in numbers. Age-dependent predation is shown to be a stabilizing influence. At the same time, with a high birth rate of the prey, the system stability is ensured by the high survival rate of adult prey. It was found that in the model parametric space, both bistability and multistability arises, which are not related to each other. Consequently, even a small variation of the current population size leads to more complex behavior of the interacting species, and can give a significant change in both the observed dynamic mode and the coexistence scenario of the species.

Comparison of Acyrthosiphon pisum (Homoptera: Aphididae) and Frankliniella occidentalis (Thysanoptera: Thripidae) as prey for the development and survival of Chrysopa pallens (Neuroptera: Chrysopidae)

Abstract The effects of two different prey species on the pre-imaginal development and survival of the green lacewing, Chrysopa pallens were determined under laboratory conditions. The developmental duration from first instar to adult emergence was shorter when larvae were fed on Acyrthosiphon pisum (22.56 ± 0.39 d) than on Frankliniella occidentalis (29 ± 0.45 d). The survival rate of lacewings from first instar to adult emergence was 22.6% higher when they were fed on A. pisum than when fed on F. occidentalis. The possible implications of these findings are applicable to mass-rearing of C. pallens and for understanding predator's biology and survival capacity in the presence of prey species evaluated and could be used in the development of an effective biological control program.

Extending r/K selection with a maternal risk-management model that classifies animal species into divergent natural selection categories

Reproduction is a defining process of biological systems. Every generation, across all species, breeding females repopulate ecosystems with offspring. r/K selection was the first theory to classify animal species by linking the rates with which breeding females repopulated ecosystems, to the stability of ecosystems. Here, I introduce a species classification scheme that extends the reach of r-K selection and CSR selection by linking breeder investments in offspring quantity, quality, and diversity to specific natural selection pressures. The species classification scheme is predicated on the assumption that high rates of predation favor breeders that invest more in offspring quantity than quality; and that spatiotemporal scarcity favors breeders that investment more in offspring quality than quantity. I present equations that convert the species classification scheme into a maternal risk-management model. Thereafter, using the equations, I classify eighty-seven animal species into the model’s natural selection categories. Species of reptiles, fish, and marine invertebrates clustered in the predation selection category. Species of birds and mammals clustered in the scarcity selection category. Several species of apex predators clustered in the weak selection category. Several species of social insects and social mammals clustered in the convergent selection category. In summary, by acknowledging breeding females as the individuals upon which natural selection acts to repopulate ecosystems with offspring, the proposed maternal risk-management model offers a testable, theoretical framework for the field of ecology.

Within-generation consequences of postsettlement mortality for trait composition in wild populations: An experimental test.

There is a critical need to understand patterns and causes of intraspecific variation in physiological performance in order to predict the distribution and dynamics of wild populations under natural and human‐induced environmental change. However, the usual explanation for trait differences, local adaptation, fails to account for the small‐scale phenotypic and genetic divergence observed in fishes and other species with dispersive early life stages. We tested the hypothesis that local‐scale variation in the strength of selective mortality in early life mediates the trait composition in later life stages. Through in situ experiments, we manipulated exposure to predators in the coral reef damselfish Dascyllus aruanus and examined consequences for subsequent growth performance under common garden conditions. Groups of 20 recently settled D. aruanus were outplanted to experimental coral colonies in Moorea lagoon and either exposed to natural predation mortality (52% mortality in three days) or protected from predators with cages for three days. After postsettlement mortality, predator‐exposed groups were shorter than predator‐protected ones, while groups with lower survival were in better condition, suggesting that predators removed the longer, thinner individuals. Growth of both treatment groups was subsequently compared under common conditions. We did not detect consequences of predator exposure for subsequent growth performance: Growth over the following 37 days was not affected by the prior predator treatment or survival. Genotyping at 10 microsatellite loci did indicate, however, that predator exposure significantly influenced the genetic composition of groups. We conclude that postsettlement mortality did not have carryover effects on the subsequent growth performance of cohorts in this instance, despite evidence for directional selection during the initial mortality phase.

A hyperiid amphipod acts as a trophic link between a scyphozoan medusa and juvenile Chinook Salmon

Gelatinous zooplankton (GZ) can impact productivity of marine ecosystems through competition with small pelagic fish and predation on early life history stages of species from multiple trophic levels. Nevertheless, GZ do not always represent ‘trophic dead ends.’ Some predators directly consume GZ, and many species host parasitoids which in turn are prey for other organisms. We characterized trophic relationships between the fried-egg jellyfish Phacellophora camtschatica, its hyperiid amphipod parasite (Hyperia medusarum), and juvenile Chinook Salmon Oncorhynchus tshawytscha in the Salish Sea. Hyperia medusarum occurred in 29–47% of Chinook Salmon stomachs over 3 years and were observed in high abundance on P. camtschatica medusae (mean = 428 individuals per medusa). Light and transmission electron microscopy confirmed the presence of morphologically similar nematocysts in the foreguts of H. medusarum from both medusae and Chinook Salmon stomachs. Occurrence of H. medusarum in Chinook Salmon diets was also positively related to an index of P. camtschatica abundance. Chinook Salmon stomachs contained almost exclusively mature female H. medusarum while males and juveniles were common on medusae. Size and sex ratio differences between hyperiids in Chinook Salmon diets and on medusae could reflect predator selectivity or sex and/or life-stage specific differences in H. medusarum behavior. Our results support previous speculation that GZ abundance may facilitate predation on hyperiids by Pacific Salmon. Hyperiid-mediated energy flow from GZ to fish is not limited to medusa-associated fish species and should be considered in studies of marine food webs.

The omnivorous predator Macrolophus pygmaeus, a good candidate for the control of both greenhouse whitefly and poinsettia thrips on gerbera plants.

The poinsettia thrips Echinothrips americanus Morgan is a relatively new pest that has spread rapidly worldwide and causes serious damage in both vegetable and ornamental plants. In this study, we investigated if and how effective this pest can be controlled in gerbera by the omnivorous predator Macrolophus pygmaeus (Rambur). Because herbivores on plants can interact through a shared predator, we also investigated how poinsettia thrips control is affected by the presence of the greenhouse whitefly Trialeurodes vaporariorum (Westwood), a pest that commonly coexists with E. americanus in gerbera. In laboratory studies, we found that the predator M. pygmaeus fed on both pests when offered together. Olfactometer tests showed a clear preference of the predators for plants infested by whiteflies but not by thrips. In a greenhouse experiment, densities of both pests on single gerbera plants were reduced to very low levels by the predator, either with both pests present together or alone. Hence, predator‐mediated effects between whiteflies and thrips played only a minor role. The plant feeding of the shared predator probably reduced the dependence of predator survival and reproduction on the densities of the two pests, thereby weakening potential predator‐mediated effects. Thus, M. pygmaeus is a good candidate for biological control of both pests in gerbera. However, further research is needed to investigate pest control at larger scales, when the pests can occur on different plants.