Observations on the feeding behaviour of Paratrichodorus anemones in relation to tobravirus transmission.

Feeding by P. anemones, an efficient vector of tobacco rattle virus (TRV), was investigated by video-enhanced interference light microscopy. Four stages were observed after transfer of individual nematodes, extracted from soil, to Nicotiana tabacum seedling roots in agar: i) acclimatisation; ii) approach and scrutiny; iii) preparation; and iv) feeding. Prior to commencement of stage 'iv' about 4 cells perforated by rapid onchiostyle thrusting remained alive, each having been almost immediately abandoned by the nematode. During the stage iv) approximately 5% of perforated cells remained alive. Feeding on individual cells was similar to that previously reported for Trichodorus similis: cells from which cytoplasm was ingested after a prolonged period of salivation were invariably killed, with adjacent cells being unaffected. During feeding a number of cells perforated but soon afterwards abandoned by P. anemones remained alive, providing an effective pathway for successful transmission of TRV to plants by the nematode.