Potential Risks of Poaceous Plants as Infectious Sources of Rice Black-Streaked Dwarf Virus Transmitted by the Small Brown Planthopper, Laodelphax striatellus

The recent reemergence of rice black-streaked dwarf virus (RBSDV) has caused severe rice yield losses in several areas of East Asia. To identify the most important infectious sources of RBSDV, we compared the susceptibility of major poaceous plants to RBSDV infection and survival and the RBSDV acquisition efficiency of a vector insect, the small brown planthopper Laodelphax striatellus. RBSDV infection and survival rates of L. striatellus were significantly high in wheat (Triticum aestivum 'Norin61') and rice (Oryza sativa 'Reiho'), indicating that these crops can be important sources of RBSDV. Our results also showed that RBSDV can complete its infection cycle between Italian ryegrass (Lolium multiflorum 'Hataaoba') and L. striatellus. These results indicate that control of RBSDV and L. striatellus on winter-spring crops of wheat and Italian ryegrass may avoid an RBSDV epidemic on rice during the following summer. In addition to infections of wheat and Italian ryegrass, RBSDV infections were detected in Avena fatua, Avena sterilis subsp. ludoviciana, Cynosurus echinatus, Festuca arundinacea, Festuca pratensis, Lolium perenne, and Vulpia myuros var. megalura, although the infection efficiency varied.