Analysis of the bacterial community in glassy-winged sharpshooter heads

The glassy‐winged sharpshooter (GWSS), Homalodisca vitripennis, is an important vector of various strains of Xylella fastidiosa, which cause disease in a variety of economically important plants. These diseases include citrus variegated chlorosis, oleander leaf scorch and Pierce's Disease of grapevines. Symbiotic control (SC) is a new strategy that uses symbiotic endophytes as biological control agents to antagonize or displace the pathogenic strains of X. fastidiosa. Candidate endophytes for use in SC must occupy the xylem of host plants and attach to the pre‐cibarium and cibarium of sharpshooter insects in order to have access to the pathogen. The study of the bacterial community of GWSS heads by isolation and denaturing gradient gel electrophoresis (DGGE) revealed the presence of species that may be suitable for use in SC. In addition, the results indicated that two important factors, insect age and choice of host plant, affect the composition of the bacterial community in GWSS heads. The main bacterial genera isolated as colonizers of GWSS heads were identified, using partial 16S rRNA gene sequencing, as Bacillus, Pseudomonas, Pedobacter and Methylobacterium, as well as the species Curtobacterium flaccumfaciens. DGGE patterns revealed a diversity of endophytic species able to colonize the GWSS head. The main genera isolated in culture were also identified using this technique. Principal component analysis (PCA) from polymerase chain reaction (PCR)‐DGGE patterns indicated that the bacteria inhabiting the GWSS head are similar to those found as endophytes inside the host plants, and that insect developmental stage and preferential feeding on one host plant species over another are important factors in determining the composition of the bacterial community in the GWSS head. However, a shift in host plants for a small period of time did not cause changes in the compositions of these communities.