Temporal resource continuity increases predator abundance in a metapopulation model: insights for conservation and biocontrol

Abstract

The amount of habitat in a landscape is an important metric for evaluating the effects of land cover and land use on biodiversity and ecosystem services, yet it fails to capture complex temporal dimensions of resource availability that could be consequential for species population dynamics. If ephemeral resources across multiple habitat patches are synchronously available, resource gaps could be detrimental to population growth. In contrast, asynchronously available resources create a mosaic of temporally complementary resources that mobile organisms can track across the landscape. Knowledge is especially lacking on the relevance of temporal complementation for tri-trophic interactions and biological pest control. Here we use a spatially-explicit predator-prey metapopulation model to test the effect of different spatiotemporal resource patterns on insect predators and their prey. We examined prey and predator responses in model landscapes that varied in both the amount and temporal variability of basal vegetation resources. Further, we examined cases where prey comprised either a single generalist species or two specialist species that use different resources available either early or late in the growing season. We found that predators and generalist prey benefitted from lower temporal variance of basal resources, which increased both of their landscape-scale abundances.However, increasing the amount of basal resources also increased the variability of generalist prey populations, resulting in a negative correlation between basal resource amount and predator abundance. Specialist prey, on the other hand, did not benefit from less temporally variable in basal resources, since they were restricted by habitat type while also suffering greater predation.Predators feeding on specialists achieved greater prey suppression in landscapes with less temporally variable resources. Our simulations demonstrate the joint importance of Spiesman et al. 3 landscape-scale temporal dynamics of resources and resource amount in understanding how landscape heterogeneity influences biodiversity and ecosystem services such as the biological control of agricultural pests.

Temporal Resource (Dis)continuity for Conservation Biological Control: From Field to Landscape Scales

“…In other words, temporal separation in the presence of alternative prey and primary pests may contribute to "apparent competition" between prey species (Langer and Hance, 2004;Blitzer and Welter, 2011), mitigating the negative effect of preferential feeding on non-pests. Similarly, a modeling study by Spiesman et al (2020) showed that fields or landscapes that…”

“…The challenge for agroecologists is to improve the scientific basis for habitat management while accounting for the context-dependency of pest and natural enemy dynamics (Settele and Settle, 2018). Temporal resource patterns are increasingly recognized as a crucial aspect of agroecosystem context, with many calling for more rigorous consideration in CBC research (Welch and Harwood, 2014;Schellhorn et al, 2015;Haan et al, 2020;Spiesman et al, 2020).…”