Changes in resistance of graminaceous plants to Delphacid planthoppers induced by maize rough dwarf virus (MRDV).
The following is substantially the authors' summary of this account of studies carried out in Israel on changes brought about by the maize rough dwarf virus (MRDV) in the relations between three species of Delphacids and certain plants [cf. also RAE A 48 419]. Laodelphax striatella (Fall.), which is the principal vector of MRDV in Israel [55 2004, etc.], cannot survive on healthy Bermuda grass (Cynodon dactylon) for more than four days. However, when the grass was infected with MRDV, the vector developed and bred on it at a rate equal to that on wheat, oats and barley, which are its natural food-plants. Merely the presence of MRDV in the vector enabled it to adapt itself to Bermuda grass. The same was true in the case of sorghum, not a normal food-plant of L. striatella, though the adaptation was only partial. Toya (Delphacodes) propinqua (Fieb.) does not normally survive on wheat, barley or oats for more than 3-7 days, but the nymphs were able to complete their development (though this was prolonged) when confined on plants infected with MRDV; the resulting adults were stunted and infertile. Sogatella vibix (Haupt) normally breeds on wheat [cf. 55 2004]. When it was caged on wheat severely infected with MRDV, most of the individuals died within three days, apparently owing to a toxic agent in the sap of the infected plants.