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

Z Barbar

doi:10.1051/acarologia/20142143

Abstract

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.

Highlights

Members of the family Tetranychidae have been widely recorded on citrus in different regions of the world (Vacante, 2010)
ISSN 2107-7207 idae are considered as the main biological control agents of tetranychid mites in citrus orchards, maintaining their population densities at low economic levels (McMurtry, 1977, 1992; Ferragut et al, 1992; Abad-Moyano et al, 2009)
As no study has been undertaken on bioecological aspects of tetranychid mites and their phytoseiid predators in Syrian citrus orchard conditions, and as mite population dynamics on citrus trees are poorly investigated during winter, the objectives of the present study were to (1) obtain preliminary data on diversity and population dynamics of phytoseiid and tetranychid mites on citrus leaves in a pesticide-free orchard; (2) provide information about species composition and phenology of phytoseiid mites during hibernation period using "Phyto traps" (Koike et al, 2000); (3) evaluate the importance of wild plant species within or around citrus orchards as possible sources and potential overwintering sites of phytoseiid mites occurred frequently on citrus trees

Summary

Introduction

Members of the family Tetranychidae have been widely recorded on citrus in different regions of the world (Vacante, 2010). Several species of this family [i.e. the citrus red mite Panonychus citri (McGregor), the oriental red mite Eutetranychus orientalis (Klein) and the two spotted spider mite Tetranychus urticae Koch] have a worldwide distribution and are considered as major pests of this culture worldwide (Jeppson et al, 1975; Gotoh et al, 2003; Vacante, 2010). Unfavourable climatic conditions (i.e. hot and dry summer ; cold winter), and mainly the application of broadspectrum pesticides lead to decrease in population densities of these natural enemies, causing population outbreaks of several tetranychid mite species (McMurtry, 1977; Garcia-Mari et al, 1983; Kasap, 2009).

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