ROLE OF BACTERIAL ATTACHMENT IN TRANSMISSION OF XYLELLA FASTIDIOSA BY THE GLASSY-WINGED SHARPSHOOTER,AND OTHER FACTORS AFFECTING TRANSMISSION EFFICIENCY

• Author(s): Purcell, Alexander; Almeida, Rodrigo; Lindow, Steven; Newman, Karyn;
• Abstract: Although it is known that Xylella fastidiosa (Xf) is located on the foregut of infected insects (infective nymphs loose transmissibility after molting and there is no latent period required for transmission), the exact location in the foregut from which the bacterium Xf is transmitted by sharpshooter leafhoppers is not known. We examined the spatial distribution of Xf in the precibarium of vectors that had been fed on infected grapevines. Xf cells attached on end to the insects cuticle and were distributed throughout the precibarium, with few exceptions, on both pharynges. Xf was not present on top of the precibarial valve, but interestingly cells were observed within the valves pit. In a transmission experiment with long inoculation access period, all infective insects transmitted Xf to healthy grapevines; individuals free of Xf on the precibarium did not vector the pathogen. An ancillary objective was to determine if the relatively low transmission rates (5-15% daily) by the glassy-winged sharpshooter (GWSS) were influenced by the plant tissue inoculated: stem or leaf. On grape, adult GWSS feed mainly on stems. In an initial experiment with low transmission rates (less than 7% per GWSS adult) there were no differences among treatments (stem only, leaf only, stem and leaf). This will be repeated with more insects per plant and longer exposure for inoculation, but these initial results suggest that feeding site on green tissues are not a major factor.
• Publication Date: Aug 2003
• Journal: 2003 Pierce's Disease Research Symposium