Monday, December 10, 2007 - 9:17 AM

Salivary secretions of the glassy-winged sharpshooter, Homalodisca vitripennis: Novel method of collection and protein profile

Hasan Alhaddad, fadak@csufresno.edu1, Elaine Backus, ebackus@fresno.ars.usda.gov2, and Fred E. Schreiber, freds@csufresno.edu1. (1) California State University, Fresno, Biology, 2555 East San Ramon ave, Fresno, CA, (2) USDA San Joaquin Valley Agricultural Research Center, 9611 S. Riverbend Ave, Parlier, CA

The glassy-winged sharpshooter, Homalodisca vitripennis Takiya (Hemiptera: Cicadellidae) is a xylophagous leafhopper that efficiently transmits Xylella fastidiosa, causative agent of a variety of scorch diseases such as Pierce’s Disease of grapes. The transmission mechanism of X. fastidiosa by the sharpshooter is presently unknown, but recent research suggests that salivation during feeding may be involved. The objective of this study was to begin biochemical investigation of the salivary secretions, by first developing a novel method of collection and subsequently analyzing the profile of collected salivary proteins. The new collection method involved brushing the sharpshooter’s labrum and clypeus using a camel hair brush and collecting the secreted salivary bubble using glass fiber paper. The collected salivary secretion samples compared with the total extract of dissected salivary glands were analyzed using SDS-PAGE, stained with Coomassie blue or silver stains. The saliva collection method proved to be more efficient than traditional techniques using an artificial diet as a medium to collect saliva. Also this method allowed observation in real time of the separation of the salivary sheath and watery saliva, by gradual solidification of part of the salivary secretion while another part remained liquid. In addition, small portions of solid sheath solubilized when more salivary secretions were produced. The SDS-PAGE revealed that the salivary secretion is a large mixture of proteins. The molecular weight of the band in highest concentration band was found to have a molecular weight of 12kD. Research is underway to characterize the major protein components of the salivary secretions.

Species 1: Hemiptera Cicadellidae Homalodisca vitripennis (glassy-winged sharpshooter)