The Influence of Sogatella furcifera (Hemiptera: Delphacidae) Migratory Events on the Southern Rice Black-Streaked Dwarf Virus Epidemics.

Southern rice black-streaked dwarf virus (SRBSDV) caused serious rice losses. After the first outbreak in 2009 in northern Vietnam and southern China, the virus ravaged crops again on enormous scales in 2010, but infections have decreased sharply since 2011. We presumed that the sudden epidemics and fadeout of SRBSDV would be closely related to the migratory events of the insect vector, Sogatella furcifera. This study sought the source area of SRBSDV using the trajectory analysis method, and revealed the relationship between SRBSDV dynamics and migration of S. furcifera populations via an in-depth analysis of meteorological background of S. furcifera migration fields. The results showed that Northern Vietnam was the direct virus source area of the SRBSDV infection in China, and South Central Coast of Vietnam was the original source area of SRBSDV. Southwesterly winds were prevalent in spring of 2010 and carried large numbers of viruliferous S. furcifera to China from northern Vietnam. This infestation of S. furcifera was the direct cause of the SRBSDV outbreak in China in 2010. In 2011, the winter-spring temperatures were abnormally low and southeasterly and easterly winds dominated; therefore, the number of viruliferous S. furcifera that entered China was small, and consequently, the occurrence area of SRBSDV was rapidly reduced. The return of viruliferous S. furcifera to South Central Coast of Vietnam was an important factor that affected the occurrence scale of SRBSDV in the following year.