Annals of Applied Biology (2014) 165, 395-403

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Y. Abou-Jawdah, A. Abdel Sater, M. Jawhari, H. Sobh, H. Abdul-Nour, P.A. Bianco, M. Molino Lova and A. Alma (2014)
Asymmetrasca decedens (Cicadellidae, Typhlocybinae), a natural vector of ' Candidatus Phytoplasma phoenicium'
Annals of Applied Biology 165 (3), 395-403
Abstract: ' Candidatus Phytoplasma phoenicium' is associated with a lethal disease of almond, peach and nectarine named almond witches'-broom disease (AlmWB). The disease spread rapidly in Lebanon from coastal areas to elevations exceeding 1200 m, killing over 150,000 trees in a span of two decades. The mode of spread suggested the involvement of efficient vector(s) and Asymmetrasca decedens (Hemiptera, Cicadellidae) was suspected as it is the most abundant leafhopper species present in Lebanese stone fruit orchards. Living A. decedens specimens were collected from fields heavily infested by AlmWB and used in transmission trials on healthy peach almond hybrid GF-677 and peach GF-305 seedlings with an inoculation-access period of 30 days. PCR analysis supported by sequencing showed that A. decedens is a carrier of the phytoplasma, and that the phytoplasma was detected in insect salivary glands and in some inoculated GF-677 and GF-305 seedlings. One year post-inoculation, ' Ca. P. phoenicium' was detected in newly emergent leaves of inoculated seedlings. However, the characteristic symptoms of witches'-broom were not observed. PCR amplified fragments from phytoplasma-positive seedlings and from A. decedens samples showed 99.9% nucleotide identity in their 16S RNA region and phylogenetic analysis using a neighbour jointing tree confirmed that the phytoplasmas detected in both insects and inoculated seedlings belonged to 16SrIX-B (D). The present manuscript is the first known report for a leafhopper vector of ' Ca. P. phoenicium' and shows that the incubation period of the disease in plants may be longer than 1 year. The importance of phytosanitary control measures, the adoption of a national strategy and regional cooperation in order to contain the further spread of the disease are discussed.
(The abstract is excluded from the Creative Commons licence and has been copied with permission by the publisher.)
Link to article at publishers website
Database assignments for author(s): Yusuf Abou-Jawdah, Piero Attilio Bianco, Alberto Alma

Research topic(s) for pests/diseases/weeds:
transmission/dispersal of plant diseases

Pest and/or beneficial records:

Beneficial Pest/Disease/Weed Crop/Product Country Quarant.

Asymmetrasca decedens Peach/nectarine (Prunus persica) Lebanon
Phytoplasma phoenicium Peach/nectarine (Prunus persica) Lebanon