Preliminary survey of potential vectors of 'Candidatus Phytoplasma phoenicium' in Lebanon and probability of occurrence of apricot chlorotic leaf roll (ACLR) phytoplasma

Malaise traps and sticky yellow traps were placed in two almond orchards infected with almond witches' broom (AlmWB) phytoplasma in 2004 and in 2010. Collected insects were tested by nested PCR using universal primers for detection of phytoplasma. In 2004 Asymmetrasca decedens, Euscelidius sp. and Fieberiella sp. gave positive results with the universal primers and also with the pigeon pea group specific primers. The mere presence of phytoplasma in an insect is not a proof that it is a vector, but it may help narrowing the choice of insects for conducting actual transmission tests. In 2010, early in the season, in over 20 species surveyed we were not able to detect phytoplasma except in Psammotettix provincialis. The PCR amplicon was sequenced (1180 bp) and found to be most closely related to the Aster yellows (AY) group 16Srl, subgroup F which includes apricot chlorotic leaf roll (ACLR) phytoplasma. Late in the season, most PCR tests were negative, the major reason was correlated with DNA degradation which resulted from the hot summer temperatures combined with the method of insect collection. The implications of these findings are discussed.