The effect of winter ploughing on reduction of pistachio weevil population density

The weevil Polydrusus davatchii Hoffmann, is a potential pest for pistachio buds and developing flower clusters in early spring. The effect of winter ploughing on weevil’s population density was investigated using emergence traps in a contaminated pistachio orchard through 2009-2012 in Bayaz, 75 Km North-West of Rafsanjan, Iran. It was found that beetles only emerges from soil where naturally covered by plant litters under the pistachio trees’ canopy during 20 March to 20 April. No adult weevil captured through emergence traps in other parts of orchard. The number of weevils that captured under trees canopy having no any plant litters were significantly less than those captured under trees canopy where naturally covered by plant litters. A significant difference was found for the abundance of weevils in plowed and non-plowed areas. In addition, the present field experiment verified that abundance of weevils on aerial parts of trees in plowed plot were significantly lower than those in non-plowed plot. Based on the results, winter ploughing (30 cm depth) of pistachio orchards causes positive effect on reduction of weevils’ population density