Physiological variation of insects in agricultural landscapes: potential impacts of climate change

Understanding the physiological and behavioural responses of insects to climate variation is critical, for several reasons, of which three are perhaps most important. First, developing a deeper understanding of pest population dynamics and postharvest control requires information on thermal (and other environmental) traits. Second, invasion of new and emerging pests into novel environments requires some knowledge of the basics of environmental physiology. Finally, to predict and manage aspects of efficacy in control programmes through the release of laboratory- or mass-reared insects typically hinges on some information from phenotype- environment interactions. Here, we provide an overview of how climate and landscape environmental opportunities vary spatially and temporally in order to quantify better ecologically meaningful microclimates for insects and to understand better behavioural opportunities in agricultural landscapes. Then, we describe several key biogeographic patterns that may be significant from an insect pest/climate change perspective, and then discuss briefly possible mechanisms associated with variation in the physiological tolerance and performance of insects. We review and discuss issues surrounding the prediction of climate change and insect physiological and behavioural responses, and consider how insect pests might be impacted by changes in climate in the future via physiological tolerances. Next, we consider movement and dispersal in agricultural landscapes, and what this may mean for recolonization potential or introduction to novel environments under climate change scenarios, especially given how many of these processes are influenced by climatic factors. Finally, this chapter examines interactions between hosts and biocontrol agents, and how climate may influence the outcome of these interactions. The chapter concludes with a summary and discussion of possible areas for future research and key themes emerging from this review of physiological variation in agricultural landscapes and the potential impacts of climate change.