Transmission of California aster-yellows virus by leafhopper species in Thamnotettix group

Abstract does not appear. First page follows.

Introduction

According to (Ball (1936)),3 the tree- and shrub-inhabiting leafhoppers have been referred in the past to the genus Thamnotettix, but are widely separated from the type of the genus and belong to a number of distinct genera. He divided the genus into nine genera.

Some years ago three leafhopper species (Severin, 1929), (1934) and a biological race (Severin, 1940) of one of these species were reported to transmit California aster-yellows virus. In recent papers (Severin, 1945), (1946), (1947a), (1947b) thirteen more species have been added to the list of vectors of this virus. The present paper deals with nine species and one variety of leafhoppers in the Thamnotettix group, two of which have been previously recorded in the literature (Severin, 1934). All were tested for transmission of California aster-yellows virus and some for transmission of the viruses of curly top and Pierce’s disease of the grapevine. The companion paper in this issue (DeLong and Severin, 1948) discusses the characters, distribution, and food plants of eight of these leafhopper species.

Methods

The cages used and the methods of transferring leafhoppers in a dark chamber were the same as in previous investigations (Severin, 1930), (1931).

The food plants used in maintaining large populations of the geminate leafhopper, Colladonus geminatus (Van Duzee), and the mountain leafhopper, C. montanus (Van Duzee), have been recorded in previous papers (Severin, 1934), (1942). Infective Idiodonus heidemanni (Ball) was reared on diseased celery and asters and noninfective leafhoppers on healthy celery and asters. The other six species and the one variety in the Thamnotettix group were collected on their natural host plants. They were not reared on celery and asters, and no attempt was made to breed them on their natural host plants.

Idiodonus Heidemanni (Ball)

Transmission of Virus to Celery. To determine the efficiency of Idiodonus heidemanni (Ball) (= Thamnotettix heidemanni Ball) in transmitting California aster-yellows virus, 50 males and 50 females that had completed the nymphal stages on infected celery were transferred singly to healthy celery plants. As table 1 shows, 12 per cent of the males and 20 per cent of the females caused infections.