Temporal change in vegetation productivity in grain production landscapes: linking landscape complexity with pest and natural enemy communities

Abstract

1. Strategies to enhance the ecosystem service of pest control in agricultural landscapes often rely on manipulating the structure of the landscape to reduce pest population build‐up or facilitate natural enemy activity. For highly mobile and polyphagous invertebrate pest species the agricultural landscape represents a continually changing mosaic of resources and habitats that at certain points in time may be conducive to high population productivity and therefore pest outbreaks. Deciding which features of the landscape we need to measure and monitor to understand this process is the first step in developing intervention strategies. Previous studies have focused on static measures of landscape composition and have generally ignored landscape configuration and change across time.2. In this study we sampled invertebrate pests and predatory natural enemies repeatedly over two years from crop, pasture and semi‐natural habitats (up to 36 sites per landscape) in multiple agricultural landscapes (14km diameter circles) across Australia's grain production regions. The temporal pattern in vegetation productivity was quantified (using remote‐sensed Normalized Differential Vegetation Index) at the landscape‐scale and related to the pest and natural enemy density data.3. Metrics derived from the vegetation show variation across time and highlight transition points in the landscape that might represent important shifts in resources for higher trophic levels. The landscape metrics that were related to pest density were different in each landscape, but generally characterized connectivity of vegetation classes (more than configuration or composition). How connected or dis‐aggregated vegetation productivity classes were appears important for pest dynamics in these landscapes.