Chapter 16 - Shifting Equilibrium of Pest and Diseases in Agriculture

Abstract

Current estimates of changes in climate indicate an increase in global mean annual temperatures of 1°C by 2025 and 3°C by the end of the next century. These changes could profoundly affect the status of insect pests, diseases, weeds and nematode of crops. These may arise not only as a result of direct effects on the distribution and abundance of pest populations, but also as a result of indirect effects on the pests’ host plants, competitors and natural enemies. Some pests which are already present but only occur in small areas or at low densities may be able to exploit the changing conditions by spreading more widely and reaching damaging population densities. Changes in climatic parameters in terms of increased temperature, humidity and carbon dioxide may result in changes in geographical distribution, increased over-wintering, changes in population growth rates, increases in the number of generations, extension of the development season, changes in crop pest synchrony of phenology, changes in interspecific interactions and increased risk of invasion by migrant pests. A number of priorities for future research into the effects of climatic changes on agricultural pests are suggested with the case examples.