title: Seasonal abundance of Draeculacephala minerva and other Xylella fastidiosa vectors in California almond orchards and vineyards.
abstract: Almond leaf scorch (ALS) disease is caused by the bacterium Xylella fastidiosa and transmitted by xylem-feeding insects. Reports of increased incidence of ALS-diseased trees in California prompted surveys in three almond [Prunus dulcis (Mill.) D. A. Webb]-growing regions, from June 2003 to September 2005, to determine insect vector species composition and abundance. For comparison, sampling in and near vineyards in the San Joaquin Valley, California, also was completed. Sampling in or near almond orchards collected >42,000 Cicadomorpha of which 4.8% were xylem feeders, including 1912 grass sharpshooter, Draeculacephala minerva Ball; five Xyphon fulgida Nottingham; and a single spittlebug, Philaenus spumarius L. The most abundant vector was D. minerva. Season-long sampling indicated that D. minerva was a year-round resident in and/or near almonds in the Sacramento Valley, but not in the San Joaquin Valley. Similarly, D. minerca was rare in vineyards in the San Joaquin Valley, but was abundant in irrigated pastures near vineyards. D. minerva was most frequently collected along orchard margins, and peak densities were observed in summer, the period of time when bacterial titers are reported to increase in infected trees. Screening of D. minerva for presence of X.fastidiosa found that 1.1% of insects collected near almond orchards and 4.5% of insects collected from pastures tested positive. The X. fastidiosa subspecies and genotype detected in insects collected from orchards matched those collected from ALS-diseased almond trees in the same orchard. Of the few X. fulgida and P. spumarius collected, none tested positive for X. fastidiosa. Results are discussed with respect to X. fastidiosa vector control and detection methods.
authors.affiliation: Department of Environmental Science, Policy and Management, University of California, Berkeley, CA 94720-3114, USA. daane@uckac.edu
authors.forename: Kent M
authors.initials: KM
authors.lastname: Daane
authors.forename: Christina M
authors.initials: CM
authors.lastname: Wistrom
authors.forename: Elaine B
authors.initials: EB
authors.lastname: Shapland
authors.forename: Mark S
authors.initials: MS
authors.lastname: Sisterson
mesh_terms: D000818:Animals; D002140:California; D006430:Hemiptera / Q000382:microbiology*; D054884:Host-Pathogen Interactions; D007303:Insect Vectors / Q000382:microbiology*; D010935:Plant Diseases; D027861:Prunus / Q000382:microbiology*; D012621:Seasons; D027843:Vitis / Q000382:microbiology; D044167:Xylella / Q000502:physiology*