Hawthorn psyllid fauna in northwestern Italy

Hawthorn is one of the natural hosts of Cacopsylla melanoneura (Förster), the main vector of ‘Candidatus Phytoplasma mali’, the causal agent of apple proliferation (AP) disease, a serious and growing problem for apple production in Europe, particularly in northern Italy. Other psyllid species are acknowledged as hawthorn feeders, but no data are available on their presence and abundance in northwestern Italy. Samplings with yellow sticky traps and beat trays were carried out in two sites located in the Aosta Valley, containing wild Crataegus monogyna Jacquin plants and surrounded by meadows, wastelands, and vineyards, in the neighbourhood of apple orchards. C. melanoneura was the predominant species followed by C. peregrina (Förster) and C. affinis (Löw), while C. crataegi (Schrank) was sampled sporadically. Other six species are only occasional migrants. The population dynamics of the two most abundant species, C. melanoneura and C. peregrina were investigated.