Delphacodes haywardi Muir, a New Natural Vector of Mal de Río Cuarto virus in Argentina

Mal de Rı´o Cuarto virus (MRCV; Fijivirus) causes one of the principal diseases of maize in Argentina and also infects a wide range of cultivated and wild species of the Gramineae.Its spread in the Argentine maizegrowing area coincides largely with the geographical distribution of Delphacodes kuscheli, its only previously known vector.Neverthele ss, the presence of MRCV in regions where D. kuscheli has not been detected, or is found only infrequently, led to the study of another delphacid species (D. haywardi) as a possible transmitter of the virus.Spe cimens of D. haywardi were collected from crops and pastures in the province of Entre Rı´os (Argentina).MRCV was transmitted by naturally infected individuals from the field, and also in experimental transmission trials with laboratory-reared populations of the same species.Virus in the D. haywardi samples was detected and identified with molecular hybridization probes, and in infected plants by observation of symptomatology, serological tests, electrophoresis of dsRNA and electron microscopy.The vector capacity of D. haywardi has very important implications in the epidemiology of this disease