A cixiid survey for natural potential vectors of ‘Candidatus Phytoplasma phoenicium’ in Lebanon and preliminary transmission trials

Abstract

Almond witches'-broom (AlmWB) disease, associated with 'Candidatus Phytoplasma phoenicium', is an emerging threat with real risk of introduction in Euro-Mediterranean Countries. Its rapid spread over large geographical areas suggests the presence of efficient insect vector(s). In the present work, a survey on cixiids was carried out in Lebanon in the years 2010-2013 in AlmWB-infested almond and nectarine orchards. Insects were collected by means of different methods, identified with a stereo microscope, and analysed for phytoplasma identification through 16S rDNA PCR-based amplification and nucleotide sequence analyses. Preliminary transmission trials were performed with the most abundant species. A list of the cixiid genera and species present in the studied area is given as well as some information about their biology. 'Ca. Phytoplasma phoenicium' strains were detected in the genera Cixius, Tachycixius, Eumecurus and Hyalesthes. Preliminary trials revealed that Tachycixius specimens were able to transmit the detected strains to healthy peach potted seedlings. Further studies are required to better clarify the taxonomic status and the bio-ethology of collected planthoppers and deeply study their role as phytoplasma vectors.

‘Candidatus Phytoplasma phoenicium’ associated with almond witches’-broom disease: from draft genome to genetic diversity among strain populations

“…P. phoenicium’ strains infecting almond, peach and nectarine in Lebanon (i) revealed a substantial genetic homogeneity within the analyzed phytoplasma populations based on house-keeping gene sequence analyses, and (ii) allowed the identification of distinct AlmWB-associated phytoplasma strains from diverse host plants based on inmp (integral membrane protein) gene sequence analysis. This evidence, along with prior reports of multiple insect vectors of AlmWB phytoplasma [ 56 , 57 ], suggests that AlmWB could be associated with phytoplasma strains derived from the adaptation of an original strain to diverse hosts.…”

“…Intriguingly, these preliminary data seem to indicate that AlmWB phytoplasma strains identified in peach plants are distinct from strains infecting almond and nectarine based on molecular markers within the inmp nucleotide sequences. Recently, insect species of the families Cicadellidae and Cixiidae have been reported to be capable of transmitting AlmWB phytoplasma [ 56 , 57 ]. Considering this evidence, it is reasonable to hypothesize the possible implication of inmp diversity on multiple vector-specific epidemiological cycles of AlmWB phytoplasma in the diverse plant hosts.…”

History and Current Status of Phytoplasma Diseases in the Middle East

“…In addition, this leafhopper has been reported from almond orchards in Iran [ 89 ]. Transmission trials by Tachycixius viperinus Dlabola and T. cypricus Dlabola revealed that they can transmit the 16SrIX-B phytoplasma to peach in Lebanon [ 90 ]. T. viperinus and T. cypricus , collected from Anthemis spp.…”

“…T. viperinus and T. cypricus , collected from Anthemis spp. and Smilax aspera , which were grown in the wild in Lebanon, also tested positive to AlmWB phytoplasma strains [ 90 ]. However, the vector of AlmWB disease has not been identified in Iran [ 73 , 80 ].…”

Identification of a 16SrIX‐B phytoplasma strain associated with Daphne mucronata phyllody in Iran

“…with witches' broom in the USA (Davis et al, 2010). Phytoplasmas are mostly transmitted by leafhoppers which can feed on different plant host species and can also be transmitted from reservoir hosts to cultivated or forest and shrub plants (Abou-Jawdah et al, 2014;Casati et al, 2016;Tedeschi et al, 2014). Little is known about the economic importance of phytoplasma infection in forest and shrub plants, including D. mucronata.…”