The glassy-winged sharpshooter (GWSS), Homalodisca coagulata (Hemiptera, Cicadellidae), has become an important vector of Xylella fastidiosa to grape, almond and oleander in California. We characterized GWSS transmission of X. fastidiosa from and to grapevines, in which the pathogen causes Pierce's disease (PD). We studied the effects on transmission of acquisition and inoculation access periods; molting; and access to green shoots, two-year old woody tissues, or dormant wood. Insects acquired X. fastidiosa from infected plants within 1 hour of access. GWSS inoculation was successful after 6 hours, but not 1 hour. The transmission rate was about 50% with 48 hours of inoculation access. Nymphs of various instars transmitted the pathogen, but lost infectivity after molting, suggesting that the source of inoculum is lost with the shed cuticle of the sharpshooter nymphs. GWSS inoculated X. fastidiosa into green shoots and woody tissues. GWSS also transmitted the bacterium into dormant plants that had been exposed to winter conditions and, during the inoculation access period, had positive root pressure. These results suggest that the mechanism of X. fastidiosa transmission is the same for different strains of the bacterium and vector tribes. They will also provide information for the development of GWSS control techniques and establishment of population thresholds for vineyards. Because of the vector's capacity to inoculate into two-year old wood and dormant plants; GWSS may generate successful infections and therefore PD, year-round. As a result, the GWSS control period, now mainly done in spring and summer, might have to be extended throughout the year.
Species 1: Hemiptera Cicadellidae Homalodisca coagulata (glassy-winged sharpshooter)
Keywords: Xylella fastidiosa, Pierce's disease
The ESA 2001 Annual Meeting - 2001: An Entomological Odyssey of ESA