Occurrence, population dynamics and winter phenology of spider mites and their phytoseiid predators in a citrus orchard in Syria

摘要

The present study aimed to clarify some bio-ecological aspects of phytoseiid and tetranychid mites in Syrian citrus orchard conditions. The main objective was to obtain preliminary data on diversity, population dynamics, and overwintering phenology of mites considered in a pesticide-free citrus orchard located in Latakia province. Mites were collected on citrus leaves, in Phyto traps attached to citrus twigs, and on wild plants within and around the orchard from mid-summer 2013 to early summer 2014. Panonychus citri was the main tetranychid species collected on citrus leaves, but in very low densities. Mobile stages of this phytophagous were absent during winter. Eight phytoseiid species were found on citrus leaves during all sampling dates, and their general mean density was four times higher compared to that of P. citri. Euseius stipulatus, Euseius scutalis and Amblyseius andersoni were the dominant species on citrus leaves and seemed to have different population dynamics, different overwintering sites and phenology in winter, apparently due to differences in climatic requirements (i.e. temperature and photophase). Some phytoseiid species were rarely observed on citrus leaves, but were collected in high number in Phyto traps. Others seemed to emigrate from wild plants to overwinter on citrus twigs. Several hypotheses were formulated to explain the results obtained.