Abstract
Tobacco rattle virus (TRV) has been detected in its natural vectors (Trichodorus spp.) by cutting up batches of infective nematodes in a drop of water and inoculating the suspension to herbaceous test plants (Sänger, Allen & Gold, 1962); the characteristic rod-shaped particles of TRV have also been seen in such preparations with the aid of the electron microscope. However, these results merely show that infective sap is ingested and are not necessarily indicative of any specific relationship between virus and vector as TRV has similarly been detected in Xiphinema and Pratylenchus nematodes which do not transmit the virus (van Hoof, 1967). Longidorus elongatus likewise ingests viruses which it does not transmit (Taylor, 1968) but in L. elongatus carrying raspberry ringspot or tomato black ring, two viruses of which it is the natural vector, we have found virus-like particles apparently specifically adsorbed on to the cuticular stylet guiding sheath (Taylor & Robertson, 1969).