Modelling the dynamic spatio‐temporal response of predators to transient prey patches in the field

Abstract

The spatio‐temporal dynamics of two aphid species (Metopolophium dirhodum and Sitobion avenae) and a generalist predator (Pterostichus melanarius) were observed in a field‐scale study using a grid of 256 sampling locations with a 12‐m spacing. Using Spatial Analysis by Distance Indices we demonstrate that populations show ephemeral spatial pattern at the field scale. We observed a positive, lagged beetle response to this aphid pattern; conversely, the aphids displayed a negative, lagged response to beetle spatial pattern. Examination of the local structure of the spatio‐temporal dynamics revealed a strong response by the beetle population to aphid patches. The temporal structure of spatial associations between the species shows a strong correspondence with those from a conceptual model of predator–prey spatial interaction. The spatially coupled dynamics were sufficiently strong for the predator to have a negative effect on the intrinsic rate of increase of their prey.

Spatiotemporal Analysis of Spread of Infections by Verticillium dahliae Pathotypes Within a High Tree Density Olive Orchard in Southern Spain

“…The spatial association between pairs of time periods was analyzed using SADIE as described by Winder et al (51). Local association was investigated using the index X k based on the similarity between clustering indices of two given time periods.…”

“…Overall spatial association X k was calculated as the mean of individual local values. Significance of X k was tested by randomizations, with cluster indices reassigned amongst the quadrats after allowance for small-scale spatial autocorrelation in the cluster indices from either population (51). The maximum number of 9,999 randomizations was performed and a two-tailed test was used to assess significance.…”

“…The maximum number of 9,999 randomizations was performed and a two-tailed test was used to assess significance. For this test, a null hypothesis of no association was used (51). Local association was calculated for each of the six possible combinations of pairs of consecutive crop seasons over the period of the study from the year 1999 to 2003.…”

Relationship between rust mitesCalepitrimerus vitis(Nalepa), bud mitesColomerus vitis(Pagenstecher) (Acari: Eriophyidae) and short shootsyndrome in Oregon vineyards

“…This index was used to measure the degree of clustering of data into areas with above-average density, or patches, or areas with below-average density, or gaps (Perry, 1995). The v indices indicate where clustering occurs, where a clustering patch is indicated by large positive values of v i (larger than 1.5) and a gap by large negative values for v i (smaller than -1.5) (Winder et al, 2001;Maestre and Cortina, 2002). Values of v i equal to 1 and v j equal to -1, indicate randomness (Winder et al, 2001;Perry and Dixon, 2002).…”

“…The v indices indicate where clustering occurs, where a clustering patch is indicated by large positive values of v i (larger than 1.5) and a gap by large negative values for v i (smaller than -1.5) (Winder et al, 2001;Maestre and Cortina, 2002). Values of v i equal to 1 and v j equal to -1, indicate randomness (Winder et al, 2001;Perry and Dixon, 2002). To test for non-randomness, the mean values of the clustering indices, v i and v j were used.…”