A koinobiont parasitoid mediates competition and generates additive mortality in healthy host populations

Cameron, Tom C.; Wearing, Helen J.; Rohani, Pejman; Sait, Steven M.

doi:10.1111/j.0030-1299.2005.13964.x

Cited by 12 publications

(19 citation statements)

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“…Thus, as unparasitized larvae, which consume the greatest resource volume , Cameron et al 2005, are less likely to survive competition in high parasitism populations, the remaining parasitized and unparasitized individuals may develop faster as they are released from competition when unparasitized competitors perish. Thus, as unparasitized larvae, which consume the greatest resource volume , Cameron et al 2005, are less likely to survive competition in high parasitism populations, the remaining parasitized and unparasitized individuals may develop faster as they are released from competition when unparasitized competitors perish.…”

Section: Discussionmentioning

confidence: 99%

“…A previous study had found a negative correlation between the number of surviving unparasitized hosts and increasing densities of parasitized hosts (Cameron et al 2005). A previous study had found a negative correlation between the number of surviving unparasitized hosts and increasing densities of parasitized hosts (Cameron et al 2005).…”

Section: Introductionmentioning

confidence: 90%

“…We argue that infected competitors represent an indirect effect of infection on a host population's reproductive fitness. While many of these risks have received attention, few empirical systems have addressed the competitive ability of infected hosts (but see Tien et al 2001, Bernstein et al 2002, Sisterson and Averill 2003, Cameron et al 2005, and fewer still have asked what the dynamical consequences of infected competitors are for host-parasitoid dynamics (Bernstein 1986, Spataro andBernstein 2004). Such an enemy-victim scenario may take the form of a parasite population that will continually reduce host fitness over some period, but only kill a host when the parasite load exceeds some threshold.…”

Section: Introductionmentioning

confidence: 99%

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Intraspecific Competition: The Role of Lags Between Attack and Death in Host–parasitoid Interactions

Cameron

Metcalfe

Beckerman

et al. 2007

Ecology

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Many natural enemies do not immediately kill their host, and the lag this creates between attack and host death results in mixed populations of uninfected and infected hosts. Both competition and parasitism are known to be major structuring forces in ecological communities; however, surprisingly little is known about how the competitive nature of infected hosts could affect the survival and dynamics of remaining uninfected host populations. Using a laboratory system comprising the Indian meal moth, Plodia interpunctella, and a solitary koinobiont parasitoid, Venturia canescens, we address this question by conducting replicated competition experiments between the unparasitized and parasitized classes of host larvae. For varying proportions of parasitized host larvae and competitor densities, we consider the effects of competition within (intraclass) and between (interclass) unparasitized and parasitized larvae on the survival, development time, and size of adult moths and parasitoid wasps. The greatest effects were on survival: increased competitor densities reduced survival of both parasitized and unparasitized larvae. However, unparasitized larvae survival, but not parasitized larvae survival, was reduced by increasing interclass competition. To our knowledge, this is the first experimental demonstration of the competitive superiority of parasitized over unparasitized hosts for limiting resources. We discuss possible mechanisms for this phenomenon, why it may have evolved, and its possible influence on the stability of host-parasite dynamics.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 90%

Section: Introductionmentioning

confidence: 99%

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Intraspecific Competition: The Role of Lags Between Attack and Death in Host–parasitoid Interactions

Cameron

Metcalfe

Beckerman

et al. 2007

Ecology

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“…Overall, fluctuating temperatures led to lower parasitoid abundance and to transient differences in host abundance between temperature treatments at all levels of resource degradation. Transient changes in the intensity of intraspecific competition (Cameron, Metcalfe, et al, ; Cameron, Wearing, Rohani, & Sait, ), coupled with resource and temperature‐dependent differences in host and parasitoid juvenile development and in parasitoid adult life span, most likely contributed to the complex patterns of population dynamics we observed in this trait‐dependent trophic interaction (Belarde & Railsback, ; de Sassi et al, ). In koinobiont parasitoids with a shorter window of host suitability than Venturia or in idiobiont parasitoids, which only attack discrete host stages (e.g.…”

Section: Discussionmentioning

confidence: 95%

Environmental degradation amplifies species’ responses to temperature variation in a trophic interaction

Mugabo

Gilljam

Petteway

et al. 2019

Journal of Animal Ecology

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Land‐use and climate change are two of the primary drivers of the current biodiversity crisis. However, we lack understanding of how single‐species and multispecies associations are affected by interactions between multiple environmental stressors.We address this gap by examining how environmental degradation interacts with daily stochastic temperature variation to affect individual life history and population dynamics in a host–parasitoid trophic interaction, using the Indian meal moth, Plodia interpunctella, and its parasitoid wasp Venturia canescens.We carried out a single‐generation individual life‐history experiment and a multigeneration microcosm experiment during which individuals and microcosms were maintained at a mean temperature of 26°C that was either kept constant or varied stochastically, at four levels of host resource degradation, in the presence or absence of parasitoids.At the individual level, resource degradation increased juvenile development time and decreased adult body size in both species. Parasitoids were more sensitive to temperature variation than their hosts, with a shorter juvenile stage duration than in constant temperatures and a longer adult life span in moderately degraded environments. Resource degradation also altered the host's response to temperature variation, leading to a longer juvenile development time at high resource degradation. At the population level, moderate resource degradation amplified the effects of temperature variation on host and parasitoid populations compared with no or high resource degradation and parasitoid overall abundance was lower in fluctuating temperatures. Top‐down regulation by the parasitoid and bottom‐up regulation driven by resource degradation contributed to more than 50% of host and parasitoid population responses to temperature variation.Our results demonstrate that environmental degradation can strongly affect how species in a trophic interaction respond to short‐term temperature fluctuations through direct and indirect trait‐mediated effects. These effects are driven by species differences in sensitivity to environmental conditions and modulate top‐down (parasitism) and bottom‐up (resource) regulation. This study highlights the need to account for differences in the sensitivity of species’ traits to environmental stressors to understand how interacting species will respond to simultaneous anthropogenic changes.

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“…For example, increased interactions with, and prolonged exposure to, hosts (Plodia interpunctella) parasitized by its parasitoid Venturia canescens reduced the survivorship of unparasitized hosts (Cameron et al 2005). Such effects could have destabilizing delay effects on host population dynamics.…”

Section: Discussionmentioning

confidence: 99%

Egg dispersion is more important than competition type for herbivores attacked by a parasitoid

2010

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Herbivore fitness can be altered by a combination of interacting organisms, such as its food plant, conspecifics, and predators/parasitoids. Here, we tested relative effects of plant species, herbivore intraspecific competition type, and spatial distribution of the herbivore among plant units on herbivore survival and whether parasitoids modified these effects. We used an endophagous bruchine seed predator Callosobruchus maculatus for the herbivore, and a braconid wasp Heterospilus prosopidis for the parasitoid. The survival rate of C. maculatus was measured for each of 16 combinations of two plants (bean species, Vigna unguiculata and V. radiata), two competition types of C. maculatus larvae (contest and scramble), two spatial distributions of hosts [sparse (1 C. maculatus larva per seed over 20 seeds) and dense (2 C. maculatus larvae per seed over ten seeds)], and with/without a parasitoid pair. In the absence of the parasitoid, C. maculatus survival rate was lower with V. radiata and in the contest type. With the parasitoid, the proportion parasitized hosts was independent of total host density. Neither the proportion of parasitized hosts nor host survival rate was affected by plant species or host strain, but they were affected by host spatial distribution. When host distribution was dense, a higher proportion of hosts were parasitized, and C. maculatus survival rate was lower. Here we discuss parasitoid potential as a selective agent for the sparse within-pod distribution of its hosts in the field.

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A koinobiont parasitoid mediates competition and generates additive mortality in healthy host populations

Cited by 12 publications

References 50 publications

Intraspecific Competition: The Role of Lags Between Attack and Death in Host–parasitoid Interactions

Intraspecific Competition: The Role of Lags Between Attack and Death in Host–parasitoid Interactions

Environmental degradation amplifies species’ responses to temperature variation in a trophic interaction

Egg dispersion is more important than competition type for herbivores attacked by a parasitoid

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