Review paper on Xylella fastidiosa and its vectors
A few species of xylem fluid-feeding insects are considered as important pests because they can transmit Xylella fastidiosa (EPPO A1 List) which induces diseases on grapevine, citrus, coffee, almond, lucerne, stone fruits, ornamental plants and hardwood trees. In particular, two diseases caused by X. fastidiosa, citrus variegated chlorosis and grapevine Pierce’s disease are currently causing problems. In Brazil, citrus variegated chlorosis became important in the early 1990s and has now expanded through many citrus-growing areas of South America. The recent establishment of Homalodisca coagulata (Homoptera: Cicadellidae – EPPO Alert List) in California has led to serious outbreaks of Pierce’s disease, and consequently to much research on insect vectors and disease management. A review paper on X. fastidiosa and its vectors presents the current knowledge on disease epidemiology and tries to identify which vectors may have the potential to invade new areas outside their natural range and become important disease vectors. Today, 39 species and 19 genera of Cicadellidae and 5 species of Cercopidae have been shown to be vectors of X. fastidiosa. In North America, the following species are reported as particularly abundant in affected crops or adjacent vegetation: Xyphon (Carneocephala) fulgida, Draeculacephala minerva, Graphocephala atropunctata, Homalodisca coagulata and Oncometopia spp. In Brazilian citrus groves, the main species found are: Dilobopterus costalimai, Oncometopia facialis, Acrogonia citrina, Bucephalogonia xanthophis.
A simplified table below presents the vector species which may have the potential to invade new areas and further spread X. fastidiosa (a more complete table is given in the review paper). The authors stressed that this list is only an attempt, as information is still incomplete for many species.
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Species
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Disease
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Distribution
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Risk
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Bucephalogonia xanthophis
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CVC
CLS
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Argentina, Brazil
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High. Common in diverse ecosystems and abundant on ornamental plants and nursery stocks
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Dilobopterus costalimai
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CVC
CLS
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Argentina, Brazil, Paraguay
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High. Common in diverse ecosystems, crops and ornamental plants
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Draeculacephala minerva
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PD
AD
ALS
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California, Hawaii, south-west and west USA, Mexico, Central America
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High. Common in diverse ecosystems
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Graphocephala atropunctata
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PD
AD
ALS
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South-west USA to Central America
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High. Common in diverse ecosystems. Associated with ornamental plants
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Macugonalia leucomelas
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CVC
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Argentina, Bolivia, Brazil, Paraguay
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High. Common in diverse ecosystems. Associated with ornamental plants and nursery trees
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Acrogonia citrina
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CVC
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Brazil
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High. Common in diverse ecosystems, ornamental plants and nursery trees
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Homalodisca coagulata
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PD
PPD
OLS
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South-east USA to Texas, California, Mexico
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High. History of range expansion on nursery stock. Ability to feed on woody tissue may allow secondary transmission of X. fastidiosa in grapes
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Oncometopia nigricans
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PD
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South USA
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High. Associated with disease epidemics, large host range.
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CVC: citrus variegated chlorosis – CLS: coffee leaf scorch – PD: Pierce’s disease – AD – alfalfa dwarf - ALS: almond leaf scorch – PPD: phony peach disease – OLS: oleander leaf scorch.
Sources
Redak RA, Purcell AH, Lopes JRS, Blua MJ, Mizell RF, Andersen PC (2004) The biology of xylem fluid-feeding insect vectors of Xylella fastidiosa and their relation to disease epidemiology. Annual Review of Entomology, 49243-270.