Experimental transmission trials by <i>Cacopsylla pyri</i>, collected from pear decline infected orchards in Turkey

Abstract

A study was carried out on the experimental transmission efficiency of the Pear Decline (PD) phytoplasma by Cacopsylla pyri (L.), collected from naturally infected orchards from Bursa and non-infected orchard from Hatay province of Turkey. C. pyri adults captured from infected orchards were directly transmitted to healthy periwinkle plants (Catharanthus roseus) whereas the second group firstly fed on infected pear for two weeks and then transferred to periwinkles. Groups of five psyllids per plant were used for transmissison tests and the study was replicated three times. The presence of ‘Candidatus Phytoplasma pyri’ in psyllids and C. roseus plants was analysed by nested PCR using P1/P7 and U3/U5 primer pairs.. Although C. pyri has limited host range, they were able to survive up to 20 days on periwinkles. Insects collected from Bursa province survived 16-20 days whereas second group from Hatay were survived 7-12 days on periwinkles. Symptoms consist of a yellowing or clearing of the veins in newly infected leaves and shortening of the internodes of the main stem. They also remain stunted and flowers were small. According to the RFLP analysis of Bursa samples, the experimental infection rate of periwinkle plants and psyllids was 33.3 % and 16.6 %, respectively. No infected periwinkle was found in second group but psyllids were 33.3 % infected. Transmission trials under controlled conditions showed the capability of C. pyri to transmit PD from infected pears to healthy periwinkles and confirmed as vector of Ca. P. pyri in Turkey.

Keywords: Candidatus Phytoplasma pyri, pear psyllid, transmission efficiency