Field evaluation on citrus fruit scars in Italy: the role of Pezothrips kellyanus (Bagnall) (Thysanoptera: Thripidae)

The results of a field trial on the damage caused by Pezothrips kellyanus (Bagnall) on lemon fruits are reported. In order to carry out the trial, a rearing of P. kellyanus was started during spring 2006 and 2007. In the first year the trial was conducted in a twenty years organic lemon orchard. Six trees were selected and five fruits per tree, with a diameter of 1.5 cm, were chosen. All these fruits were caged with a fine polyester mesh bag; four of them were inoculated with five female thrips collected in the laboratory rearing, while the fifth was treated as control. The fruits were exposed to thrips activity for 1, 2, 3, and 4 weeks and then weekly checked in order to verify the surface conditions. In 2007, the trial was repeated in an integrated lemon orchard on older plants (30 years). The trial conducted in 2006 inoculating P. kellyanus gave evidence of a presence of an epidermic alteration already after a week from fruit exposition to the thrips feeding activity. The damage became gradually more evident after 2, 3 and 4 weeks showing a presence of irregularly distributed scars that could interest large portions of the fruit surface. This kind of alteration was present on all fruits inoculated with P. kellyanus with high damage level. Differently, in 2007 the results were inconsistent, probably also due to extreme temperature conditions.