Impact of Temperature and Rainfall Change on Epidemics caused by Plant viruses

Abstract

Plant virus diseases are one of the limiting factors to crop productivity by diminishing the quantity, quality and responsible for significant economic losses worldwide. The Epidemic of plant virus diseases is the result of interactions between virus, host plant, vector, and environmental factors. Changes in host plants and insect vector dynamics that result from temperature and rainfall change could have an influence on the spread of plant viruses. The rising of temperature and heat stress increase the susceptibility of host plants to virus infection and accelerates the fitness of viruses to cause disease. The increasing temperature also changes insect vector population dynamics by accelerating insect phenology, causing earlier and prolonged colonization because it makes appropriate environmental conditions for the insect vectors. Insect populations of most virus vectors build up more rapidly in areas with high temperatures and high relative humidity and decline at low temperature. In addition, the rising temperatures can increase the efficiency of virus transmission from infected to healthy plants by insect vectors. An increasing frequency of heavy rainfall events is likely to slow the virus prevalence and incidence by washing insect vectors, thus reducing vector density. Flooding within annual crop growing period enhances the subsequent growth of weed and volunteer crop plant which act as reservoirs of insect vectors and the viruses, and its occurrence outside growing seasons increases subsequent growth of such reservoirs.