Identification of Nedotepa curta Dmitriev as a potential vector of the Côte d’Ivoire lethal yellowing phytoplasma in coconut palms sole or in mixed infection with a ‘Candidatus Phytoplasma asteris’-related strain

Abstract

Over 360 Hemiptera specimens were collected using sweep nets and hand-made aspirators from coconut palm fronds in six villages of Grand-Lahou. Eight families were identified including Aphrophoridae, Achilidae, Derbidae, Flatidae, Membracidae, Pentatomidae, Tropiduchidae, and Cicadellidae, the latter being the most abundant throughout the surveyed villages. PCR assays with primers targeting the 16S rRNA and the secA translocation protein genes yielded PCR amplicons from 216 out of 296 (73%) of the tested specimens of a newly identified cicadellid leafhopper, Nedotepa curta Dmitriev. PCR amplicons were purified, cloned and sequenced. The 16S rDNA and secA sequences from N. curta showed a 99% of sequence identity with those of the Côte d'Ivoire lethal yellowing (CILY) phytoplasma, member of subgroup 16SrXXII-B 'Candidatus Phytoplasma palmicola'-related strain, previously identified in coconut-growing villages of Grand-Lahou. This suggested N. curta as a potential vector for the CILY phytoplasma. Four symptomatic coconut palms (7.4%) were found infected by a phytoplasma of group 16SrI, in mixed infection with the CILY phytoplasma (16SrXXII-B) in two palms, and alone in the other two palms, where the CILY phytoplasma was not detected. The 16SrI phytoplasma was also found in two N. curta specimens, and in the weeds Dalbergia saxatilis and Baphia nitida. Results indicating that mixed infection of both 16SrXXII-B and 16SrI phytoplasmas occurs in coconut palms affected by CILY in Grand-Lahou, and may impact disease management and control.

Global Scenario on Phytoplasmal Diseases in Palms

“…Despite the extensive transmission studies conducted in Ghana from 1990s, the vector of CSPWD in Ghana remains unknown (Philippe et al, 2009;Danyo, 2011). Several hemipteran insects have been reported as putative vectors of palm phytoplasmal diseases based on PCR results (Dollet et al, 2011;Kumara et al, 2015;Kwadjo et al, 2018;Alhudaib et al, 2007a, Pilotti et al, 2014, but their vector status has not yet been established by cage transmission trials. Tanne et al ( 2001) developed a feeding medium approach as an alternate method to bypass the use of caged palms in the preliminary vector screening trials.…”

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“…Indeed, it is associated with phytoplasmas belonging to the group of 16SrXXII (Arocha-Rosete et al, 2014), the propagation of which is generally done by stinging-sucking insects of the Homoptera species, in particular, the Cicadellidae family (Nelson 1979;Weintraub & Beanland, 2006). Thus, an epidemiological study carried out by the Plant Health Unit of Nangui Abrogoua University made it possible to identify Nedotepa curta as a carrier of the phytoplasma and therefore suspected of being a probable vector of this disease (Kwadjo et al, 2018). Nedotepa curta (Homoptera: Cicadellidae) belongs to the Typhlocybinae subfamily which nymphs and adults transfer pathogenic microorganisms by feeding on it (Della guistina et al, 1992).…”

Cíxidos y dérbidos (Hemiptera) vectores putativos de fitoplasma del grupo 16Sr-IV

“…En la provincia de Cabo Delgado, norte de Mozambique, se descubrió que algunos Pentatomidae de las especies Platacantha lutea (Westwood, 1844) portaban el mismo fitoplasma identificado en cocotero enfermo . Con este mismo enfoque, Cicadellidae de la especie Nedotepa curta Dmitriev, 2016 y el Derbidae, Proutista fritillaris (Boheman, 1838) fueron encontrados positivos al fitoplasma causante del amarillamiento letal de Costa de Marfil (CILY) (Kwadjo et al 2018). Cabe señalar, que la detección positiva a fitoplasma en un insecto, no demuestra su capacidad como vector del patógeno; sin embargo, estas detecciones pueden ayudar para que los investigadores realicen experimentos de transmisión con vectores putativos (Bila et al 2017).…”