Citrus infestation by the black scale,Parlatoria ziziphiLucas (Homoptera: Diaspididae) in Tlemcen, Algeria

Abstract

In a 2-year study on black scale, Parlatoria ziziphi Lucas (Homoptera, Diaspididae) infestation on two citrus varieties viz., Thomson and Portuguese at El Fehoul station in Tlemcen North-West of Algeria, Parlatoria ziziphi was found infesting both varieties. The upper surface of leaves was always more infested than the lower surface by Parlatoria ziziphi for both Thomson and Portuguese varieties. In terms of leaves infestation rates, it's very important at the southern exposure and the center of the plot for Thomson variety, and with 100% in the southern and northern exposure of the Portuguese variety. In case of fruit, the rate of infestation is the most important in the south of plot with 87.9% for Thomson variety and 79% for the Portuguese variety. The infestation rate of the leaves does not change after harvesting the fruit. This species of scale insect is cosmopolitan and attacks many species of Citrus family. It is also very common on citrus in Algeria.