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Temperature and Transmission of the Western X-Disease Agent by Colladonus montanus. D. D. Jensen, Professor, Division of Entomology, University of California, Berkeley 94720; Phytopathology 62:452-456. Accepted for publication 29 November 1971. DOI: 10.1094/Phyto-62-452.

Previously noninfective Colladonus montanus leafhoppers were injected with extract from leafhoppers infected with the Western X-disease agent (WXA). The leafhoppers were then caged singly on small celery plants used as disease indicators, and kept at constant temperatures ranging from 10 to 30 C. Another group of insects was maintained in a plant growth chamber programmed to run alternately at 15 and 30 C for 12 hr during each 24-hr period. Test insects were transferred to new plants weekly or twice weekly. The median incubation period of WXA in leafhoppers kept at constant temperatures was shortest (26 days) at 25 C, and longer at either higher (38 days at 30 C) or lower (125 days at 15 C) temperatures. Only one of 83 insects held at 10 C transmitted WXA. The most favorable constant temperature for the development of infectivity in injected insects was 20 C. Only 4 and 24% of the insects injected as nymphs became infective at 30 and 15 C, respectively. However, 75% of the insects maintained alternately at 15 and 30 C became infective. Therefore, variable temperatures, even some that are unfavorable when held constant, may be more conducive to vector efficiency than are constant temperatures. Retention of WXA by C. montanus and insect longevity were, in general, inversely proportional to the temperatures at which the insects were held.

Additional keywords: mycoplasma, virus, leafhopper vectors.