Indagini sulla presenza di Prays oleae in oliveti a conduzione biologica della Sicilia occidentale

Investigations on presence of Prays oleae in organic olive orchards of western Sicily. This paper reports a study on the population dynamics of the olive moth, Prays oleae (Bern) (Lep., Plutellidae) in four organic olive orchards in western Sicily (Italy), from 2007 to 2010. The influence of the phytophagous on the fruit drop was detected. Also, the efficacy of treatments with Bacillus thuringiensis var. kurstaki on damage reduction was evaluated. Flight trend was monitored using delta-wing traps (3/ha) containing the sexual pheromone ((Z)-7-tetradecenal), placed in each olive orchard. Traps were hung in the inner zone of the canopy to a height of 1.50 m, and checked weekly from May to 2-3 days after the olive harvest. Capture data indicated that flight peaks occurred on June-July and September-October. In 2007, the population density of P. oleae moths was generally lower than the subsequent three years . The fruit infestation levels in all years were under 5% and a greater susceptibility of Biancolilla and Cerasuola var. than Nocellara var. were detected. In 2008, the fruit drop caused by P. oleae ranged from 12% to 47% in two orchards studied. Finally, the results for two years indicate that treatments with Bacillus thuringiensis (Bt) can significantly reduce the fruit fall caused by phytophagous in comparison with untreated olive orchards.