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Epidemiology of apple proliferation (AP) in northwestern Italy: evaluation of the frequency of AP‐positive psyllids in naturally infected populations of Cacopsylla melanoneura (Homoptera: Psyllidae)
Author(s) -
TEDESCHI ROSEMARIE,
VISENTIN CRISTINA,
ALMA ALBERTO,
BOSCO DOMENICO
Publication year - 2003
Publication title -
annals of applied biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.677
H-Index - 80
eISSN - 1744-7348
pISSN - 0003-4746
DOI - 10.1111/j.1744-7348.2003.tb00252.x
Subject(s) - biology , phytoplasma , population , amplicon , veterinary medicine , vector (molecular biology) , psylloidea , homoptera , botany , nested polymerase chain reaction , polymerase chain reaction , horticulture , pest analysis , restriction fragment length polymorphism , genetics , gene , medicine , demography , sociology , recombinant dna
Summary Adults of Cacopsylla melanoneura , vector of the apple proliferation (AP) phytoplasma, were collected every 2 weeks from January until May in 2000 and 2001 by the beating tray method in eight apple orchards of the Aosta Valley (northwestern Italy). Total DNA was extracted from batches of five insects and amplified with the universal phytoplasma primers P1/P7 in direct PCR. A nested PCR assay was then performed on P1/P7 amplicons using the primers fO1/rO1, specific for the AP‐ phytoplasma group. The digestion of fO1/rO1 amplicons with Ssp I restriction endonuclease confirmed that C. melanoneura adults harboured the AP phytoplasma. The data obtained with PCR were used to estimate the proportion of AP‐positive insects in over wintered and offspring adults. Percentages of AP‐positive insects of 3.6% and 0.8% were estimated in 2000 among over wintered and offspring psyllids respectively. In 2001 only the over wintered insects were found infected, with an estimated proportion of 2.8%. The seasonal abundance of the vector was measured using yellow sticky traps. C. melanoneura was always present at a low population level, and the highest density was recorded from mid‐February until mid‐March in both years. The results show that the overwintered population is higher and spends a longer period in apple orchards, suggesting the crucial role of the overwintered adults in vectoring AP.