Studies on the transmission of sugar-beet yellows virus by the aphis, Myzus persicae (Sulz.)

Previous studies on the relationship between plant viruses and their insect vectors have been carried out which viruses which are easily mechanically transmissible and whose vectors lose their infectivity within a few hours of removal from the source of infection. This type of virus has been called (Watson and Roberts 1939) non-persistent, for it was observed that the property in which viruses of this type resemble each other, and differ from those viruses whose vectors retain their infectivity for long periods, namely, the persistent viruses. It seems that these differences must lie in the nature of the viruses themselves, for viruses of both types can be transmitted by the same vector. Sugar-beet yellows virus (Petherbridge and Stirrup 1935) seems to be a member of the persistent class, for its vector, Myzus persicae, the same insect as was used in previous work on non-persistent viruses (Watson 1936, 1938; Watson and Roberts 1939), remains infective for several days after removal from the source of infection (Roland 1939). Also it is not transmissible mechanically by any of the usual methods (Quanjer 1934, 1936). The present paper, therefore, describes some studies on the vector-virus relationships of this virus by the methods which have been used previously only on the non-persistent types.