Transmission of Rice Stripe Virus by Laodelphax striatellus Fallén

Abstract

Microscopic examination of salivary sheaths, which were produced as stylet tracks by allowing small brown planthopper, Laodelphax striatellus Fallén, to feed on agar film, revealed that the salivary sheath is generally shaped like a sword and varies in length and in number of branches according to instars and adult sex of the hopper tested. Observation on point of feeding and path of penetration in rice leaf, differentially stained by erythrosine, indicated that the hoppers prefer the veins and paths of the inserted stylets direct mostly toward the vascular tissue. Furtheron the access of salivary sheaths to sieve tube and to vessel were in the ratio of 73 to 27 in leaf blade and 67 to 33 in leaf sheath, respectively. Thus the stylet punctures by small brown planthopper are found to terminate mostly in vascular bundles, particularly in phloem, accompanied with several branchings. The hoppers formed far less stylet tracks on the epidermis of leaf sheath in stripe-resistant varieties than in susceptible varieties. From living or frozen pieces of leaf sheath on which viruliferous hoppers had been fed for 1 to 6 hours, another species of planthopper. Unkanodes albifascia Matsumura, featuring outstanding compatibility with stripe virus, could recover the virus. Equality in heat-stability of the virus given off from viruliferous hoppers with that in diseased leaf blade and other evidence suggest that the virus is of protein coated.