Influence des composés phénoliques des feuilles de Citrus, sur le développement des larves de Phyllocnistis citrella Staint. (Lepidoptera ; Gracillariidae) dans un milieu semi contrôlé.

Abstract

The absence of Phyllocnistis citrella infestations on the spring shoots seems to be linked to the chemical composition of Citrus foliage. A weekly sampling was conducted during the phenological cycle of two Citrus species: Citrus sinensis and C. clementina. This work was, in a first time, to assess the impact of the crude phenolic extract of spring flushes on the ethology of P. citrella larvae (L1 – L2 – L3). The results indicate that the treatments have resulted in a significant mortality especially after application of irrigation method whose action has been rapid. Similarly, a cessation of the food intake was recorded during the first few hours (6h) of contact by irrigat ion. The youngest larval stages (L1 and L2) appear to be the most sensitive. In a second time, the chemical composition (carbon, nitrogen, and phenolic compounds) of their oviposition sites has been studied to determine its food quality. The results indicate that even in the presence of a high content of phenolic compounds (C. sinensis = 18.78 ; C. clementina = 35.99 mg/g MS), the increase in the nutritional level C/N (C. sinensis = 9.89 ; C. clementina = 11.7), and carbon (C. sinensis = 6.67 ; C. clementina = 7.22 % MF), in summer, influence positively the P. citrella activity (C. sinensis = 95.89 , C. clementina = 94 % ). Citrus leaves, as a source of nutrients, play a decisive role in P. citrella population dynamics.