Detail and the devil of on-farm parasite control under climate change

Levels and seasonal patterns of parasite challenge to livestock are likely to be affected by climate change, through direct effects on life cycle stages outside the definitive host and through alterations in management that affect exposure and susceptibility. Net effects and options for adapting to them will depend very strongly on details of the system under consideration. This short paper is not a comprehensive review of climate change effects on parasites, but rather seeks to identify key areas in which detail is important and arguably under-recognized in supporting farmer adaptation. I argue that useful predictions should take fuller account of system-specific properties that influence disease emergence, and not just the effects of climatic variables on parasite biology. At the same time, excessive complexity is ill-suited to useful farm-level decision support. Dealing effectively with the 'devil of detail' in this area will depend on finding the right balance, and will determine our success in applying science to climate change adaptation by farmers.