Some biological characteristic and population fluctuations of citrus whitefly, Dialeurodes citri Ashmead (Hemiptera: Aleyrodidae) in citrus orchards of northe of Iran

Whiteflies are considered as citrus orchards pests in the north of Iran. The whitefly consumes large quantities of sap with its sucking mouthparts and weakens the plant. Further injury is caused by sooty mold fungus, Capnodium citri Berk. & Desm., which grows over fruit and foliage in the copious amount of honeydew excreted by the whitefly. This black fungus may cover the leaves and fruit so interferes with the proper physiological activities of the trees. In this investigation, biology and dynamics of the dominant species, citrus whitefly, Dialeurodes citri was studied in the west of Mazandaran province. Weekly sampling was done. Sampling of the adult stage was done with 4 leaves from 5 trees (20 samples). Sampling of other stages of the pest (egg, nymph, puparium) was taken according to Naranjo and Flint method (1994). The results indicated that adult insects of first generation emerged in late May. The peak of adult population was in mid June, early August and late September, respectively. Population density of the pest was high in citrus orchards, especially in nurseries and young citrus orchards. It was found that a complete life cycle took 50 days in summer. Depending on the conditions, the eggs hatching took 10-28 days. Nymphal stage took 21-32 days. The pupal stage was 10-14 days during summer. The pest overwinters as last nymphal stage and pupae under leaf underside. Citrus whitefly has 3 generations in a year.