In the summer of 1999, the first symptoms of what appeared to be a ¢yellows¢ disease were observed in Limonium ¢Beltlaard¢ flowers in the Arava Valley (Jordan Rift Valley south of the Dead Sea), Israel. Symptoms included leaf yellowing, production of abundant long and narrow leaves, production of small and/or white flowers, excessive branching similar to ¢Asparagus ferns¢, and occasionally production of leaf-like structures instead of flowers. Although a closely related flower (Statice sinuata) from the same family (Plumbaginaceae) is often grown in adjacent plots, no symptoms have yet been observed. Transmission electron microscopy and polymerase chain reaction (PCR) confirmed the presence of phytoplasma in the symptomatic plants. In December 2000 work started on monitoring potential vectors by use of yellow sticky traps and vacuum sampling. To date four species known to vector phytoplasmas and/or spiroplasmas have been trapped: Orosius orientalis (Matsumura), Circulifer haematoceps (Mulsant et Rey), C. tenellus (Baker) and Exitanius capicola Stål. Austroagallia sinuata (Mulsant et Rey) and Psammotettix spp. have also been trapped; however, since they are caught only occasionally and in very low numbers, they are not being seriously considered as potential vectors. Field collected O. orientalis, which occurs in the largest numbers, C. haematoceps and C. tenellus have tested positive for phytoplasma by PCR analysis. Transmission studies with field-collected specimens have been initiated and initial results indicate that O. orientalis can vector phytoplasma to clean Limonium plants in the laboratory. Transmission studies are continuing with other species and with clean colony O. orientalis. Possible control methods will be discussed.
Species 1: Homoptera Cicadellidae Orosius orientalis
Species 2: Homoptera Cicadellidae Circulifer tenellus
Species 3: Homoptera Cicadellidae Circulifer haematoceps
The ESA 2001 Annual Meeting - 2001: An Entomological Odyssey of ESA