Habitat heterogeneity stabilizes the spatial and temporal interactions between cereal aphids and parasitic wasps06 October 2015
Although it is widely recognized that landscape heterogeneity (LH) can enhance the activity of natural enemies, little is known about the effect of LH on the spatial and temporal stability of pests and their natural enemies. Here, we designed a gradient of LH in agro-ecosystems and examined experimentally the relationship between LH and the spatial and temporal stability of cereal aphids and their parasitic wasps from 2009 to 2012. Stability was measured by the reciprocal of the spatial and temporal coefficients of variation of the population density. Results showed that LH can significantly homogenize the distribution of cereal aphids and their parasitic wasps, thus enhancing the spatial stability of the system. Increasing LH further dampened the fluctuation of the populations of primary parasitoids and hyperparasitoids, thus enhancing the temporal stability of the system. The stability of parasitism and hyperparasitism was also improved with the increase of LH, with the hyperparasitism being more sensitive to the heterogeneity change. Consequently, integrated pest management in agro-ecosystems could be better studied from a multi-trophic food-web perspective.