Evolution of Phyllocnistis citrella Stainton (Lepidoptera, Gracillariidae) and its parasitoids in the last five years in citrus orchards of western Sicily (Italy)

Phyllocnistis citrella Stainton (Lepidoptera: Gracillariidae), is native to India, China, and other Southeast Asian countries that has spread rapidly since 1993 to all citrus-growing areas of the world. In Italy, the pest was first discovered during the autumn of 1994, in some citrus groves of Sardinia and, subsequently, in Sicily in the summer of 1995 showing a very rapid range expansion in other citrus-growing regions of Italy. Currently, damage to mature trees under typical Mediterranean conditions is considered only aesthetical, but P. citrella causes economic problems on young trees, nurseries, and overgraftings. Since the first occurrence of the citrus leafminer in Sicily, several indigenous natural enemies have been found attacking the pest, although only few parasitoid species were observed living on this phytophagous in the last years. The aims of this study were to monitor the population dynamics and mortality of P. citrella, and its natural enemies with parasitism levels, from 2002 to 2006, in some unsprayed citrus orchards in western Sicily, Italy. Results showed differences on dynamics of stages of P. citrella and of its parasitoid complex related to climate effects. Also, the monthly percentage mortality and parasitism are reported. The major percentage of parasitism was imputable to Citrostichus phyllocnistoides Narayanan and Semielacher petiolatus (Girault).