Cacopsylla melanoneura is a vector of Apple proliferation phytoplasma
In recent years, Apple proliferation phytoplasma (EPPO A2 quarantine pest) has become an increasing problem in apple orchards in Italy. In earlier studies, the psyllid species Cacopsylla costalis (synonym C. picta) had been identified as a vector of Apple proliferation phytoplasma in Trentino (northern Italy) and Germany (see EPPO RS 2003/047 and 2001/068). Studies were done in apple orchards from 1999 to 2001 in the Val d’Aosta and included: observation of symptoms in apple orchards with PCR confirmatory tests, collection of psyllids (yellow sticky traps and beating), detection of phytoplasma in psyllids and transmission trials. Apple proliferation phytoplasma was indeed present in the Val d’Aosta orchards studied. It is pointed out that the disease had not previously been reported in this area. Psyllids collected in the apple orchards were identified as Cacopsylla melanoneura (Homoptera: Psyllidae). Results of PCR detection in insect body and transmission trials showed that this psyllid species can transmit Apple proliferation phytoplasma. Observations made in Italian orchards confirmed that C. melanoneura overwinters in adult stage and has one generation per year. Overwintered psyllids started to colonize apple trees in January, and springtime generation was observed in early May. Offspring adults remained in apple orchards until the end of June, when they began to move onto other hosts. In 2000/2001, seasonal abundance of C. melanoneura was measured using yellow sticky traps. The vector was always present at low population levels, and highest density was recorded from mid-February until mid-March. This showed that the overwintered population is higher and spends a longer period in apple orchards, suggesting that overwintered adults of C. melanoneura may play a crucial role in the transmission of the phytoplasma.
Tedeschi, R.; Bosco, D.; Alma, A. (2002) Population dynamics of Cacopsylla melanoneura (Homoptera: Psyllidae), a vector of Apple proliferation phytoplasma in Northwestern Italy.
Journal of Economic Entomology, 95(1), 544-551.
Tedeschi, R.; Visentin, C.; Alma, A., Bosco, D. (2003) Epidemiology of apple proliferation (AP) in north western Italy: evaluation of the frequency of AP-positive psyllids in naturally infected populations of Cacopsylla melanoneura (Homoptera: Psyllidae).
Annals of applied Biology, 142(3), 285-290.