Xylella fastidiosa is a bacterial plant pathogen that causes many plant diseases, among those Pierce’s disease of grapevines. X. fastidiosa is naturally disseminated by sharpshooter leafhoppers (Hemiptera, Cicadellidae) vectors. Although the basic mechanism of pathogen transmission is not understood, it is known that the bacterium inoculum source is located on the foregut of infected insects, since infective nymphs loose transmissibility after molting and there is no latent period required for transmission. We studied the spatial distribution of X. fastidiosa on the precibarium area of the foregut of vectors that had access to infected plants. We found that cells attached polarly to the insect’s cuticle, and were distributed thoroughly the precibarium, with few exceptions on both pharynges. X. fastidiosa was not present on top of the precibarial valve, but interestingly cells were observed within the valve’s pit. In a transmission experiment with long inoculation access period, all infective insects transmitted X. fastidiosa to healthy grapevines; individuals free of bacteria on the precibarium did not vector the pathogen.
Species 1: Homoptera Cicadellidae Graphocephala atropunctata
Keywords: disease transmission, vectors
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