Frequency of some serotypes of viruses causing agent of yellow dwarf disease and seasonal changes in their vectors population in wheat and barley in Shahrekord

Viral diseases with natural vector in Chahar Mahal va Bakhtiari province in most occasions cause economic damage. During 2006-2008, Rhopalosiphum padi, Schizaphis graminum, Sipha elegans, Sitobion avenae, Rhopalosiphum maidis and Metopolophium dirhodum in order of frequency, respectively, were identified as the most important vectors of barley yellowdwarfvirus and cerealyellowdwarfviruses in Shahrekord. barley yellow dwarf virus-PAV (PAV), barley yellow dwarf virus-MAV (MAV) and cereal yellow dwarf virus-RPV (RPV) serotypes, respectively, were abundant. Aphid populations increased from late September and reached to the peak in mid-October. With the onset of early fall frosts,, nymph of some species moved to crown and roots of wheat and barley but none of the species were capable of overwintering in wheat and barley. There were relationships between incidence of serotypes PAV, MAV and RPV in wheat, barley and aphid vector population due to vector-serotype specificity. Under greenhouse conditions, based on symptoms and ELISA, were shown PAV by R. padi, S. avenae, M. dirhodum and S. graminum, MAV by S. graminum, R. maidis, R. padi and M. dirhodum and RPV by R. padi and S. avenae were transmitted.