Parasitoids and hyperparasitoids ofZeiraphera diniana [Lep., Tortricidae] and their pole in population control in outbreak areas

Delucchi, V.

doi:10.1007/bf02371940

Cited by 23 publications

(33 citation statements)

References 17 publications

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“…Thus, contrary to previous studies, we find that parasitoid-budmoth interaction appears to be the dominant factor driving the budmoth cycle. The fact that parasitism does not peak until budmoth is already in decline was previously taken as evidence against the parasitism hypothesis (Delucchi 1982). However, our model shows that this phase lag is consistent with parasitism driving the cycles (Fig.…”

Section: Summary Of Lbm Resultssupporting

confidence: 67%

“…The density of budmoth larvae (third instar) is expressed in number per unit of 1 kg of branches with foliage. For the period of 1952-1976 (with one year, 1968, missing) we have data on the percentage of larvae parasitized, also averaged over multiple sites (Delucchi 1982) omitting several data points that were interpolated by the author. Although numerous parasitoids are associated with larch budmoth, parasitism is dominated by the ichneumonid Phytodietus griseanae and three eulophid species, whose fluctuations are correlated (R 2 ϭ 0.94 between log Phytodietus abundance and log eulophid abundance, P Ͻ 0.001).…”

Section: Sources Of Datamentioning

confidence: 99%

“…Measured parasitism rates vary between lows of 1-5% and highs of 80-90% (Delucchi 1982), and maximum parasitism rates are achieved ϳ2 yr after budmoth peaks. Previous studies concluded that mortality by parasitoid wasps does not cause the cycle, but merely tracks the budmoth population (Delucchi 1982, Baltensweiler andFischlin 1988).…”

Section: Introductionmentioning

confidence: 99%

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Dynamical Effects of Plant Quality and Parasitism on Population Cycles of Larch Budmoth

Turchin

Wood²,

Ellner

et al. 2003

Ecology

141

149

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Abstract. Population cycles have been remarkably resistant to explanation, in part because crucial experiments are rarely possible on appropriate spatial and temporal scales. Here we show how new approaches to nonlinear time-series analysis can distinguish between competing hypotheses for population cycles of larch budmoth in the Swiss Alps: delayed effects of budmoth density on food quality, and budmoth-parasitoid interactions. We reexamined data on budmoth density, plant quality, and parasitism rates. Our results suggest that the effect of plant quality on budmoth density is weak. By contrast, a simple model of budmoth-parasitoid interaction accounts for 90% of the variance in budmoth population growth rates. Thus, contrary to previous studies, we find that parasitoid-budmoth interaction appears to be the dominant factor driving the budmoth cycle.

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Section: Summary Of Lbm Resultssupporting

confidence: 67%

Section: Sources Of Datamentioning

confidence: 99%

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Dynamical Effects of Plant Quality and Parasitism on Population Cycles of Larch Budmoth

Turchin

Wood²,

Ellner

et al. 2003

Ecology

141

149

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“…The first three instars feed between larch needles, late third and fourth instars create tubular cases by spinning needles together, and fifth instars move freely among branches. In the summer, fifth instar larvae descend to the forest floor to pupate in mineral and leaf litter (26). Adults eclose in the fall, at which time they mate, disperse, lay eggs, and die before winter (13); thus, generations are nonoverlapping.…”

Section: Systemmentioning

confidence: 99%

“…Mortality rates caused by parasitoids attacking LBM can reach levels as high as 90% (26). Of the more than 100 parasitoid species associated with LBM, only a small subset significantly affects LBM population dynamics.…”

Section: Systemmentioning

confidence: 99%

Climatic warming disrupts recurrent Alpine insect outbreaks

Johnson

Büntgen

Frank

et al. 2010

Proc. Natl. Acad. Sci. U.S.A.

133

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Climate change has been identified as a causal factor for diverse ecological changes worldwide. Warming trends over the last couple of decades have coincided with the collapse of long-term population cycles in a broad range of taxa, although causal mechanisms are not well-understood. Larch budmoth (LBM) population dynamics across the European Alps, a classic example of regular outbreaks, inexplicably changed sometime during the 1980s after 1,200 y of nearly uninterrupted periodic outbreak cycles. Herein, analysis of perhaps the most extensive spatiotemporal dataset of population dynamics and reconstructed Alpine-wide LBM defoliation records reveals elevational shifts in LBM outbreak epicenters that coincide with temperature fluctuations over two centuries. A population model supports the hypothesis that temperature-mediated shifting of the optimal elevation for LBM population growth is the mechanism for elevational epicenter changes. Increases in the optimal elevation for population growth over the warming period of the last century to near the distributional limit of host larch likely dampened population cycles, thereby causing the collapse of a millennium-long outbreak cycle. The threshold-like change in LBM outbreak pattern highlights how interacting species with differential response rates to climate change can result in dramatic ecological changes.traveling wave | tree rings | tri-trophic | Lepidoptera | parasitoids C limate change affects biotic systems in a number of ways, including elevational species range shifts (1), changes in phenology (2), extinction (3), and altered results of biotic interactions such as with competitors and natural enemies (4, 5). Global warming has recently been implicated in elevational range shifts of plants (1, 6) and animals (7, 8) at various spatiotemporal scales (9). Range shifts are often slow and may lag behind climate changes, and thus, effects of recent warming may not yet be observable (10). Patterns of population dynamics within an established range, however, should respond more quickly to external forcing, sometimes within several generations. Over the last few decades, regional scale warming trends have coincided with the collapse of population cycles across a broad range of taxa, leading to the hypothesis that such collapses are the result of climatic forcing (11,12). However, a mechanistic understanding of cycle collapses has proven to be challenging because of limited long-term data on cyclical populations. Most such records are restricted to only a few population cycles-too few to robustly confirm changes in dynamical behavior and attribute them to causal factors.Larch budmoth [LBM; Zeiraphera diniana Gn. (Lepidoptera: Torticidae)] population dynamics are a classic example of regular population cycles (13), because outbreaks have occurred periodically, almost without fail, every 8-10 y since A.D. 800 (14). The oscillations span a remarkable five orders of magnitude between population density peaks and troughs (13). Spatiotemporal patterns of 20th century LBM out...

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Parasite‐mediated selection on host phenology

MacDonald

Brisson

2023

Ecology and Evolution

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The timing of seasonal activity, or phenology, is an adaptive trait that maximizes individual fitness by timing key life events to coincide with favorable abiotic factors and biotic interactions. Studies on the biotic interactions that determine optimal phenology have focused on temporal overlaps among positively‐interacting species such as mutualisms. Less well understood is the extent that negative interactions such as parasitism impact the evolution of host phenology. Here, we present a mathematical model demonstrating the evolution of host phenological patterns in response to sterilizing parasites. Environments with parasites favor hosts with shortened activity periods or greater distributions in emergence timing, both of which reduce the temporal overlap between hosts and parasites and thus reduce infection risk. Although host populations with these altered phenological patterns are less likely to mature and reproduce, the fitness advantage of parasite avoidance can be greater than the cost of reduced reproduction. These results illustrate the impact of parasitism on the evolution of host phenology and suggest that shifts in host phenology could serve as a strategy to mitigate the risk of infection.

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Parasitoids and hyperparasitoids ofZeiraphera diniana [Lep., Tortricidae] and their pole in population control in outbreak areas

Cited by 23 publications

References 17 publications

Dynamical Effects of Plant Quality and Parasitism on Population Cycles of Larch Budmoth

Dynamical Effects of Plant Quality and Parasitism on Population Cycles of Larch Budmoth

Climatic warming disrupts recurrent Alpine insect outbreaks

Parasite‐mediated selection on host phenology

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