Detection and analysis of Xylella fastidiosa in glassy-winged sharpshooter (Homalodisca vitripennis) populations in Texas

The glassy-winged sharpshooter, Homalodisca vitripennis (H. vitripennis), (Germar) is a xylophagous insect that is an endemic pest of several economically important plants in Texas. H. vitripennis is the main vector of Xylella fastidiosa (Wells), the bacterium that causes Pierce's disease and is capable of traveling long distances putting much of the Texas grape production at risk. Understanding the movement of H. vitripennis populations capable of transmitting X. fastidiosa into Pierce’s disease-free areas is critical for developing a management program for the disease. To that end, 49 vineyards across Texas were sampled during 2005 and 2006 over the months of May, June and July. From eight vineyards in different regions of Texas, H. vitripennis were recovered from yellow sticky traps and tested for the presence of X. fastidiosa. The foregut contents were vacuum extracted and analyzed using Quantitative Real-Time PCR (QRT-PCR) to determine the percentage of H. vitripennis within each population that harbor X. fastidiosa and have the potential to transmit this pathogen. With only three individual exceptions, H. vitripennis testing positive for X. fastidiosa were found in vineyards known to have sustained PD infection.