VIEW ARTICLE

Vector Relations

Transmission of Spiroplasma citri by Circulifer tenellus. Hsing- Yeh Liu, Postdoctoral research plant pathologist, Department of Plant Pathology, University of California, Riverside 92521; D. J. Gumpf(2), G. N. Oldfield(3), and E. C. Calavan(4). (2)(4)Associate professor, and professor emeritus, respectively, Department of Plant Pathology, University of California, Riverside 92521; (3)Research entomologist, Agricultural Research Service, U.S. Department of Agriculture, Western Region, Boyden Entomology Laboratory, Riverside, CA 92521. Phytopathology 73:582-585. Accepted for publication 21 October 1982. Copyright 1983 The American Phytopathological Society. DOI: 10.1094/Phyto-73-582.

The beet leafhopper, Circulifer tenellus, can transmit Spiroplasma citri isolate MV101 acquired either by injection, membrane feeding, or feeding directly on host plants infected with S. citri; however, minimum length of the latent period varied with the three methods. Minimum latent periods were 10, 16, and 24 days for injection, feeding on plants infected with S. citri, and membrane feeding, respectively. The minimum acquisition access period for transmission was 6 hr; one of 16 test plants became infected. During a 48-hr period, the transmission rate did not increase with longer acquisition access periods. The minimum transmission time was 2 hr, when one of 16 test plants had become infected. Transmission increased with increased transmission periods to a maximum after 48 hr when 12 of 16 test plants had become infected. Number of leafhoppers also affected the transmission of S. citri. When a single insect was used, 2- 4% of the test plants became infected. For groups of 2, 5, 10, and 20 leafhoppers, the percentage of infected plants was 14- 18%, 20- 25%, 66- 75%, and 70- 80%, respectively. Transmission data showed that after the fourth transfer in a culture medium, S. citri isolate MV101 lost pathogenicity and/or transmissibility. No transovarial transmission of S. citri by C. tenellus could be demonstrated.