Limits...
Host plant quality, spatial heterogeneity, and the stability of mite predator-prey dynamics.

Daugherty MP - Exp. Appl. Acarol. (2010)

Bottom Line: However, the highest level of plant quality did not produce the least stable dynamics, which is inconsistent with the "paradox of enrichment".Heterogeneity in plant productivity had modest effects on stability, with the only significant difference being less variable T. urticae densities in the heterogeneous compared to the corresponding homogeneous treatment.These results are generally congruent with metapopulation theory and other models for spatially segregated populations, which predict that stability should be governed largely by relative movement rates of predators and prey--rather than patch quality.

View Article: PubMed Central - PubMed

Affiliation: Department of Integrative Biology, University of California, Berkeley, CA 94720, USA. matt.daugherty@ucr.edu

ABSTRACT
Population dynamics models suggest that both the over-all level of resource productivity and spatial variability in productivity can play important roles in community dynamics. Higher productivity environments are predicted to destabilize consumer-resource dynamics. Conversely, greater heterogeneity in resource productivity is expected to contribute to stability. Yet the importance of these two factors for the dynamics of arthropod communities has been largely overlooked. I manipulated nutrient availability for strawberry plants in a multi-patch experiment, and measured effects of overall plant quality and heterogeneity in plant quality on the stability of interactions between the phytophagous mite Tetranychus urticae and its predator Phytoseiulus persimilis. Plant size, leaf N content and T. urticae population growth increased monotonically with increasing soil nitrogen availability. This gradient in plant quality affected two correlates of mite population stability, population variability over time (i.e., coefficient of variation) and population persistence (i.e., proportion of plant patches colonized). However, the highest level of plant quality did not produce the least stable dynamics, which is inconsistent with the "paradox of enrichment". Heterogeneity in plant productivity had modest effects on stability, with the only significant difference being less variable T. urticae densities in the heterogeneous compared to the corresponding homogeneous treatment. These results are generally congruent with metapopulation theory and other models for spatially segregated populations, which predict that stability should be governed largely by relative movement rates of predators and prey--rather than patch quality.

Show MeSH
Mean (±SE) change in Tetranychus urticae density of all stages combined among fertilizer levels between the first and fifth censuses. Points with different letters denote significant differences
© Copyright Policy
Related In: Results  -  Collection


getmorefigures.php?uid=PMC3040825&req=5

Fig1: Mean (±SE) change in Tetranychus urticae density of all stages combined among fertilizer levels between the first and fifth censuses. Points with different letters denote significant differences

Mentions: The change in T. urticae population density between the first and fifth censuses differed significantly among fertilizer levels (F4,21 = 7.287, P = 0.0008). Mite population density failed to increase at the lowest fertilizer level, but was increasingly positive at higher fertilizer levels (Fig. 1). T. urticae densities at the final census showed a similar pattern, with mean densities (±SE) of 1.17 (±0.46), 7.44 (±2.35), 13.61 (±2.61), 13.32 (±2.35), and 17.61 (±2.86) mites/cm2 at 0, 5, 10, 20, and 40 mM N, respectively. These results suggest that fertilizer levels of 0, 5, and 15 mM N would provide a near-linear gradient of plant quality on which to study T. urticae–P. persimilis interactions.Fig. 1


Host plant quality, spatial heterogeneity, and the stability of mite predator-prey dynamics.

Daugherty MP - Exp. Appl. Acarol. (2010)

Mean (±SE) change in Tetranychus urticae density of all stages combined among fertilizer levels between the first and fifth censuses. Points with different letters denote significant differences
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3040825&req=5

Fig1: Mean (±SE) change in Tetranychus urticae density of all stages combined among fertilizer levels between the first and fifth censuses. Points with different letters denote significant differences
Mentions: The change in T. urticae population density between the first and fifth censuses differed significantly among fertilizer levels (F4,21 = 7.287, P = 0.0008). Mite population density failed to increase at the lowest fertilizer level, but was increasingly positive at higher fertilizer levels (Fig. 1). T. urticae densities at the final census showed a similar pattern, with mean densities (±SE) of 1.17 (±0.46), 7.44 (±2.35), 13.61 (±2.61), 13.32 (±2.35), and 17.61 (±2.86) mites/cm2 at 0, 5, 10, 20, and 40 mM N, respectively. These results suggest that fertilizer levels of 0, 5, and 15 mM N would provide a near-linear gradient of plant quality on which to study T. urticae–P. persimilis interactions.Fig. 1

Bottom Line: However, the highest level of plant quality did not produce the least stable dynamics, which is inconsistent with the "paradox of enrichment".Heterogeneity in plant productivity had modest effects on stability, with the only significant difference being less variable T. urticae densities in the heterogeneous compared to the corresponding homogeneous treatment.These results are generally congruent with metapopulation theory and other models for spatially segregated populations, which predict that stability should be governed largely by relative movement rates of predators and prey--rather than patch quality.

View Article: PubMed Central - PubMed

Affiliation: Department of Integrative Biology, University of California, Berkeley, CA 94720, USA. matt.daugherty@ucr.edu

ABSTRACT
Population dynamics models suggest that both the over-all level of resource productivity and spatial variability in productivity can play important roles in community dynamics. Higher productivity environments are predicted to destabilize consumer-resource dynamics. Conversely, greater heterogeneity in resource productivity is expected to contribute to stability. Yet the importance of these two factors for the dynamics of arthropod communities has been largely overlooked. I manipulated nutrient availability for strawberry plants in a multi-patch experiment, and measured effects of overall plant quality and heterogeneity in plant quality on the stability of interactions between the phytophagous mite Tetranychus urticae and its predator Phytoseiulus persimilis. Plant size, leaf N content and T. urticae population growth increased monotonically with increasing soil nitrogen availability. This gradient in plant quality affected two correlates of mite population stability, population variability over time (i.e., coefficient of variation) and population persistence (i.e., proportion of plant patches colonized). However, the highest level of plant quality did not produce the least stable dynamics, which is inconsistent with the "paradox of enrichment". Heterogeneity in plant productivity had modest effects on stability, with the only significant difference being less variable T. urticae densities in the heterogeneous compared to the corresponding homogeneous treatment. These results are generally congruent with metapopulation theory and other models for spatially segregated populations, which predict that stability should be governed largely by relative movement rates of predators and prey--rather than patch quality.

Show MeSH