Responses of Insect Pests and Plant Diseases to Changing and Variable Climate: A Review

Natural and anthropogenic factors have resulted in altered environmental conditions that influence changes in abundance and diversity of insect pests. Global climate change projections focus on crop yields and adaptation strategies to declining yields and ignore the likely impact of a changing climate on insect pests and plant diseases. In this research paper, we review the effects of climate variables namely temperature, carbon dioxide (CO2), precipitation and extreme weather events on insect pests and plant diseases incidence. Elevated temperatures, CO2 and extreme weather events have been shown to alter the distribution, reproductive potential, the incidence and abundance of plant insects and diseases in temperate regions because of the dependence of insects and diseases on environmental conditions. There is limited information on the influence of temperature and carbon dioxide as well as their interaction on the incidence and severity of insect pests, bacterial and viral diseases in the tropical regions. Information on the influence of altered precipitation patterns is also limited but could be of importance in insect distribution studies in a changing climate. Some tropical insects pests are most likely to suffer from extreme heat, resulting in death and hence pest extinction. Future research should focus on the interaction of elevated temperature and CO2, determine the influence of supra optimal summer temperatures, temperature variability, precipitation variability and the corresponding viral and bacterial diseases.