Recent Rice stripe virus Epidemics in Zhejiang Province, China, and Experiments on Sowing Date, Disease–Yield Loss Relationships, and Seedling Susceptibility

Abstract

Rice stripe virus, transmitted by the small brown planthopper Laodelphax striatellus, has recently reemerged as a major disease in Zhejiang province, eastern China. Intensive surveys during 2003 to 2006 demonstrated how the disease has spread rapidly from the northern to central and eastern regions with increasing incidence each year. In bioassays, the highest proportions of viruliferous vectors were from regions where the disease was most severe. The greatest disease incidence was in the earliest sown plants, and substantial control could be achieved by delaying planting from late May to mid-June. In experiments where different proportions of infected plants were established (by inoculation or varying the sowing date), average yield losses were 0.8% for every 1% increase in disease incidence. In inoculation experiments, young seedlings, particularly those at the three- to five-leaf stage, were the most susceptible, whereas ≤1% of plants inoculated at or after the elongation stage developed symptoms. Recent epidemics appear to have resulted from large populations of viruliferous vectors colonizing rice seedlings at the most susceptible stage. This is probably because of changes in cropping practice, recent warmer winters in Zhejiang province, and the development of resistance or tolerance to the insecticides widely used (triazophos, synthetic pyrethroids, and Imidacloprid).

The 2008 overseas mass migration of the small brown planthopper, Laodelphax striatellus, and subsequent outbreak of rice stripe disease in western Japan

“…In conclusion, the severe occurrence of L. striatellus with high viruliferous rates continues in Jiangsu Province (Zhu, personal communication), and the incidence of rice stripe disease in Zhejiang Province has spread from the northern to southern part (Wang et al, 2008). If the density of viruliferous L. striatellus in southeastern Chinese provinces remains high in the future, overseas migrations similar to the 2008 case could occur repeatedly.…”

Differences in Rice stripe virus transmission abilities of Laodelphax striatellus (Homoptera: Delphacidae) from four geographical populations

“…japonica is grown. Severe crop losses caused by rice stripe disease in 2001, 2003, 2004, and 2006 in Jiangsu, Zhejiang, Shandong, Anhui and Henan provinces have been reported (Zhou et al, 2004;Sang et al, 2006;Zhang et al, 2007;Wang et al, 2008).…”

Recent Status of Insecticide Resistance in Asian Rice Planthoppers

“…In addition to the two rice planthoppers, outbreaks of the small brown planthopper (SBPH), Laodelphax striatellus (Fallén), and rice striped virus (RSV) have occurred in China since the early 2000s 19 . The outbreaks of SBPH and RSV also occurred in Japan in 2008 11,14 .…”