Striate mosaic of cereals in Europe and its transmission by Delphacodes pellucida (Fab.)

A virus disease that resembles wheat striate mosaic was found affecting up to 5 % of the plants in English wheat fields in 1956. Symptoms on wheat included fine chlorotic striae, followed by stunting, general chlorosis, and death of plants. Other hosts included oats, barley, rye, perennial rye grass and Italian rye grass. The virus was transmitted by Delphacodes pellucida (Fabricius) (Homoptera, Delphacidae). A few of the insects were already infective when caught in the field. The percentage of infective individuals was increased by feeding the insects for 24 hr. or longer on diseased plants, and up to 56 % became infective after feeding on diseased plants for 3 days. Non-infective. e insects were unable to transmit the virus until from 8 to 36 days after they first fed on diseased plants, but they frequently remained infective for the remainder of their lives, up to 10 weeks after feeding on a diseased plant. Infective insects seldom transmitted the virus during test feeds as short as 30 min. When fed for I or more days on each test plant, some insects infected many plants in succession, others seldom infected test plants even if they fed as long as 7 days on each. The virus was transmitted through the eggs to as many as 88% of the progeny of infective females, and to some of the progeny of a few females that had failed to infect wheat test plants.