Southern rice black-streaked dwarf virus (SRBSDV) threatens rice production in China and Vietnam. The virus is vectored by the migrating white-backed planthopper (WBPH, Sogatella furcifera) in a circulative, propagative, and persistent manner. A persistently-transmitted plant virus might affect its vector's development and fecundity directly by infecting the vector itself and/or indirectly altering the host plant. This study evaluated the direct and indirect effects of SRBSDV on WBPH performance to better understand the virus-vector-host plant relationship in terms of its effects on the biological parameters of the vector.
Three experimental WBPH populations were established. Viruliferous and non-viruliferous populations were fed on SRBSDV-infected rice seedlings for 48 h as first-instar nymphs; infection status was confirmed by RT-PCR after they died. The control population was fed on healthy rice. Each insect was individually transferred to a healthy rice plant grown in a glass tube at 20°C, 25°C, or 28°C. Life parameters, including nymphal duration, survival rate, adult sex ratio, macropterous proportion, longevity, and oviposition amounts, of each population were measured at each temperature.
The life parameter data indicated that SRBSDV and infected rice plants adversely influenced WBPH; the effects were temperature dependent. Compared with the control population, viruliferous populations showed significant changes, including prolonged nymphal stages and reduced survival rates at 20°C, while the non-viruliferous population had higher survival rates at 20°C and lower rates at 28°C compared with the control. Both populations had significantly shorter adult life spans at 25°C and lower oviposition amounts at 28°C relative to the control.
Both SRBSDV-infection and feeding on infected rice plants affected vector performance. Although a longer nymphal period benefits viral acquisition and transmission by nymphs and might increase rice infection rate, in general, SRBSDV infection of the vectors and host plants was unfavorable to WBPH population expansion.