Virus-induced plant volatiles modulate insect vector conditional preference to enhance viral transmission

Insect vectors that transmit persistent plant viruses mostly show a conditional preference, wherein non-viruliferous vectors prefer virus-infected hosts over virus-free ones, and once the vector acquires the virus, this preference is reversed. Nevertheless, the precise timing of when vectors change this conditional preference, and whether virus-induced plant volatiles influence this initiation process remains largely unexplored.

Working with the insect vector green rice leafhoppers (GRLHs), rice dwarf virus (RDV) and rice plants, we observed that GRLHs did not consistently show conditional preference during RDV replication and proliferation in rice plants. When rice was infected with RDV for 30 days, GRLHs began to exhibit conditional preference, which persisted for a period of 5 days. During the period when GRLHs exhibited conditional preference, RDV infection significantly induced the emission of 2-heptanone, 2-heptanol and α-cedrene by rice plants. Non-viruliferous GRLHs are attracted to 2-heptanone and viruliferous GRLHs are repelled, whereas α-cedrene does not affect non-viruliferous GRLHs but viruliferous GRLHs are attracted. Furthermore, the combination of all three volatiles attracted non-viruliferous GRLHs feeding on RDV-infected plants, while repelling viruliferous GRLHs feeding on RDV-free plants.

These novel findings illustrate that GRLHs only exhibit conditional preference during specific stages of viral infection, and the resulting blend of volatiles modify the behavior of GRLHs and promotes RDV acquisition and transmission. They will provide a critical window period for controlling the transmission of the virus through manipulation of plant volatiles to regulate insect vector populations. © 2025 Society of Chemical Industry.