In vitro rearing of Perkinsiella saccharicida and the use of leaf segments to assay Fiji disease virus transmission.

Fiji leaf gall (FLG) is caused by the Reovirus, Fiji disease virus (FDV), which is transmitted to sugarcane by planthoppers of the genus Perkinsiella. Low vector transmission rates and slow disease symptom development make experimentation within the FDV-Perkinsiella-sugarcane system inherently difficult. A laboratory-based technique was devised to rear the vector using sugarcane leaves as a food source. Planthoppers were reared on sugarcane leaf segments embedded in agarose enclosed within plastic containers. To provide a nondestructive assay for determination of the inoculation potential of planthoppers, FDV was detected by reverse transcription-polymerase chain reaction (RT-PCR) in newly infected sugarcane leaf segments following exposure to viruliferous planthoppers. Leaf segment inoculation correlated with development of FLG symptoms in whole plants that were fed on by the same planthoppers. Analysis of FDV RNAs within the planthopper, measured by quantitative RT-PCR (qRT-PCR), indicated that FDV RNA concentration was associated with successful inoculation of the leaf segment, transmission of FDV to sugarcane and subsequent development of FLG in plants. Quantification of FDV RNA within planthoppers provided an additional measure to assess vector competence in individuals.