Distribution pattern of developmental stages of Phyllocnistis citrella Stainton (Lepidoptera: Gracillariidae) on the surface of citrus leaves

The leafminer Phyllocnistis citrella (Stainton, 1856) (Lepidoptera: Gracillariidae), is considered a potential serious pest of citrus in Algeria. The aim of this work was to investigate the relationship between the ecophases of the citrus leafminer and the leaf surface of the Washington navel citrus variety. Practically all the examined leaves of the young shoots were occupied by at least a developmental stage of this insect. More than 80% of the leafminer ecophases were distributed on the lower surfaces of the leaves. A relationship is highlighted between the leaf surfaces and the stages evolution of citrus leafminer. The choice of area laying by females is decisive for the survival and evolution of stages of development of the insect in relationship with leaf age. The analysis of the eggs distribution revealed that young leaves, with leaf surface smaller than 2 cm², were significantly preferred by females for oviposition. However, the larvae were abundant on leaf surfaces smaller than 6 cm² which provide a favorable environment for the development of larvae in order to realize their respective gallery. The pupal stage was observed almost uniformly on all the analyzed area classes. These results could contribute to the guidelines for pest risk assessment highlighting the intervention for the protection of citrus orchards against heavy infestations of Phyllocnistis citrella.