Human Activity Played a Key Role in Rice Stripe Disease Epidemics: From an Empirical Evaluation of over a 10-Year Period

Paddy is an artificial ecosystem driven by human activities, such as adjustment of cropping systems, deployment of resistant varieties and pesticides use. Inappropriate human intervention aggravated the disruption of ecosystems, which resulted in rice viral disease epidemics characterized by fulminant, migrating and intermittent outbreaks. Rice stripe disease (RSD), lasting for over 10 years from 2000, was modeled for exploring better management strategies of plant viral disease transmitted by insect vectors. In eight counties of Jiangsu province, China, the biotic, abiotic and human factors between 2000 and 2012 were monitored to determine key factors of human activities related to RSD epidemics. RSD severity was significantly related to resistance, the interval of wheat harvest and rice sowing (WHRS) and inconsecutive interval of wheat sowing and rice harvest (WSRH). The relationship between human activities and the small brown planthopper (SBPH) showed that the resistance was more significantly associated with SBPH viruliferous rate in the preceding year than that of the current year but not correlated with SBPH density. Resistance could impact the SBPH viruliferous rate in the preceding year indirectly through transmission probability and, thereafter, the continuing disease epidemics. The insignificant interactive effects among resistance, WHRS and WSRH on disease severity meant that these three factors could be taken into consideration separately in agricultural practice according to rice chronological order. The quantitative field study conducted in Jiangsu province presented a good example of plant viral disease management, guided by which could not only avoid pointless actions but, most importantly, generate more efficient and economic returns. Therefore, in order to improve the management of RSD, it should focus on the adjustment of these human factors independently and sequentially in combination with the forecast of RSD.