Vector relationships and other characteristics of barley yellow striate mosaic virus (BYSMV)

Abstract

SUMMARYBarley yellow striate mosaic virus (BYSMV) was inoculated by its planthopper vector Laodelphax striatellus (Homoptera, Delphacidae) to 44 species of Gramineae, 26 of which in eight tribes were infected. The virus was not transmitted through wheat seed nor did it infect five dicotyledonous hosts of other rhabdoviruses. The most susceptible species were in the tribes Festuceae and Hordeae. Barley, Bromus spp., oats, Phalaris canariensis, Setaria italica, Sorghum spp., and sweet corn cv. Golden were diagnostic hosts. Electron microscopy of crude sap was also a sensitive diagnostic method. Properties of BYSMV were determined by injecting L. striatellus with crude sap from infected barley. Sap was infectious after 10 min at 50–55 °C but not after 10 min at 60 °C, when diluted with buffer to 10‐‐2 but not to 10‐‐3, when stored for 2 but not 4 days at 5 °C or when kept for 1 but not 2 days at 22 °C.The planthopper Javesella pellucida was an experimental vector of BYSMV but the virus was not transmitted by the leafhoppers Macrosteles sexnotatus or Psammotettix striatus (Homoptera, Cicadellidae). The latent period of BYSMV in L. striatellus was most commonly 15 or 16 days (minimum, 9 days; maximum, 29 days). The minimum acquisition access period for transmission was between 1 h and 5 h, and the minimum inoculation feeding time was 15 min. After 24 h and 8 day acquisition feeds, 30.4% and 42.8% respectively of L. striatellus transmitted BYSMV. When transferred daily, infective hoppers transmitted virus intermittently. The maximum retention of infectivity by L. striatellus was 36 days.Two of five infective females transmitted BYSMV transovarially. Larvae became infective in the second wk after hatching and transmitted for up to 3 wk.