Rice dwarf virus infection alters green rice leafhopper host preference and feeding behavior.

Host plants, pathogens and their herbivore vectors systems have complex relationships via direct and indirect interactions. Although there are substantial gaps in understanding these systems, the dynamics of the relationships may influence the processes of virus transmission and plant disease epidemics. Rice dwarf virus (RDV) is mainly vectored by green rice leafhoppers (GRLHs), Nephotettix cincticeps (Uhler) (Hemiptera: Cicadellidae) in a persistently circulative manner. In this study, host plant selection preferences of non-viruliferous and viruliferous (carrying RDV) GRLHs between RDV-free and RDV-infected plants were tested. Non-viruliferous GRLHs preferred RDV-infected rice plants over RDV-free rice plants, and viruliferous GRLHs preferred RDV-free rice plants over RDV-infected rice plants. In odor selection preference bioassay using a four-field olfactometer, non-viruliferous GRLHs preferred odors of RDV-infected rice plants over healthy rice and viruliferous GRLHs preferred odors of RDV-free rice plants over RDV-infected ones. In 6 h plant penetration behavior bioassay using electrical penetration graphs, non-viruliferous GRLHs spent shorter time in non-penetration and much longer time in xylem feeding on RDV-infected, compared to RDV-free rice plants. Viruliferous GRLHs exhibited more salivation and stylet movement on RDV-free rice plants than on RDV-infected rice plants. We infer from these findings that RDV influences these vector behaviors by altering host plant physiology to promote viral transmission.