VIEW ARTICLE

Vector Relations

Transmission of Spiroplasma citri Lines and Their Ability to Cross Gut and Salivary Gland Barriers Within the Leafhopper Vector Circulifer tenellus. Astri C. Wayadande, Department of Plant Pathology, 110 Noble Research Center, Oklahoma State University, Stillwater 74078; Jacqueline Fletcher, Department of Plant Pathology, 110 Noble Research Center, Oklahoma State University, Stillwater 74078. Phytopathology 85:1256-1259. Accepted for publication 20 July 1995. Copyright 1995 The American Phytopathological Society. DOI: 10.1094/Phyto-85-1256.

Spiroplasma citri lines all derived from a single phytopathogenic strain, BR3-3X, but differing in subculturing or maintenance history, were tested for transmission to a susceptible plant host after injection into the leafhopper vector Circulifer tenellus and for their ability to cross both the gut and salivary gland barriers in the insect. BR3-T (a line maintained in turnips by leafhopper transmission) was detected in leafhoppers 18 days after injection and in plants exposed to injected leafhoppers. Plants exposed to leafhoppers injected with BR3-P (a line subcultured in artificial medium more than 130 times) and BR3-G (a line maintained in periwinkle over 8 years by graft transmission) did not become diseased. However, like BR3-T, both of these lines were detected in leafhoppers 18 days after injection. In a separate experiment, a fourth line, BR3-M, that had been passed in liquid culture 43 times, retained insect transmissibility. After leafhoppers fed on suspensions of spiroplasmas, BR3-T was readily recovered from the hemolymph after a 6-wk latent period, whereas BR3-P was rarely recovered and BR3-G was never recovered. Similarly, BR3-T was recovered from solutions fed upon by injected insects after a 14-day latent period, whereas BR3-P was rarely recovered and BR3-G was never recovered. Thus, although all lines multiply within the hemocoel, the ability to traverse insect gut and salivary gland barriers has been lost in BR3-G and significantly impaired in BR3-P.