Intraspecific competition: The role of lags between attack and death in host-parasitoid interactions

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Intraspecific competition: The role of lags between attack and death in host-parasitoid interactions. / Cameron, T. C.; Metcalfe, Dan; Beckerman, A. P.; Sait, S. M.

In: Ecology, Vol. 88, No. 5, 2007, p. 1225-1231.

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Cameron, T. C. ; Metcalfe, Dan ; Beckerman, A. P. ; Sait, S. M. / Intraspecific competition: The role of lags between attack and death in host-parasitoid interactions. In: Ecology. 2007 ; Vol. 88, No. 5. pp. 1225-1231.

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TY - JOUR

T1 - Intraspecific competition: The role of lags between attack and death in host-parasitoid interactions

AU - Cameron, T. C.

AU - Metcalfe, Dan

AU - Beckerman, A. P.

AU - Sait, S. M.

PY - 2007

Y1 - 2007

N2 - 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.

AB - 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.

KW - parasitized competitors

KW - purasitoid-host dynamics

KW - Plodia

KW - interpunctella

KW - resource competition

KW - Venturia canescens

U2 - 10.1890/06-0661

DO - 10.1890/06-0661

M3 - Article

VL - 88

SP - 1225

EP - 1231

JO - Ecology

JF - Ecology

SN - 0012-9658

IS - 5

ER -