Agriculture is affected by climate change, with particularly adverse effects in developing countries. Climate change also influences the ecology of weeds, pests and disease, with possible implications for crop protection and pesticide use. Elevated atmospheric carbon dioxide (CO2) influences plant growth and the nutritional quality of most plant species, with potential bottom up effects. Increased temperature causes migration of species northwards and into higher latitudes, while in the tropics higher temperatures might adversely affect specific pest species. However, an agro-ecosystem consists of more than the crops and the pests, natural enemies play a critical role in crop protection, and so far climate change research has largely neglected them.
This paper reviews existing scientific literature about the ecological consequences of climate change and elevated atmospheric carbon dioxide on weeds, pests (insects, mites, slugs and nematodes), diseases and their natural enemies (parasitoids, pathogens and predators). The objective was to investigate if there is any observable trend that could imply that pressure from weeds, pests and diseases might increase due to climate change and elevated carbon dioxide (CO2).
The results show a clear research bias towards elevated carbon dioxide and insect herbivory in temperate regions, therefore, available information applies mostly to these areas. Although increased temperature might outweight some effects of elevated CO2, experiments combining both parameters have been rare. Little research has been conducted on weeds and plant diseases under climate change. When it comes to natural enemies, it seems climate change ecology research still remains in the 1980s, where scientists never looked beyond the second trophic level. The conclusion regarding crop protection is that anything can happen. However, crop protection has always been dynamic and climate change might increase the speed of changes. Farmers can cope with these changes when considering five basic measures. When it comes to pesticide use, climate as influencing factor plays a minor role, economy, policy, education and agronomy are the main drivers of pesticide use.