Damage on sweet orange fruits by the mite Polyphagotarsonemus latus (Banks) and the population of its predatory mites in Southwestern Nigeria.

摘要

Scars and blemishes on citrus fruits render them unacceptable to prospective local buyers as well as the export market. To ameliorate this situation, the populations of the phytophagous mite Polyphagotarsonemus latus (one of the agents at the origin of the damage observed) and its predatory mites were assessed in an orchard in the National Horticultural Research Institute (NIHORT), Ibadan, Nigeria, during the 2000 and 2001 fruiting seasons. The damage inflicted upon the fruits of 12 varieties of orange trees was studied jointly. The aim of the study was to identify appropriate periods to initiate control and to assess varietal effects on mite attack. Twelve varieties of sweet oranges were used for the study. A stand of each variety was sampled per replicate to assess mite population and damage. Mite populations and their damage on sweet orange varieties increased to fruit maturity. Washington Navel, Valencia Late, Agege and Lue Gin Gong varieties were most susceptible to mite attack and recorded higher fruit damage than the other varieties. The populations of the predominant predatory mites (the Bdellidae family) that attacked P. latus were significantly (P<0.05) correlated with their prey at high population periods. The detrimental effects of pesticide overuse on natural enemies were highlighted. The progressive increase in mite population suggests the need for initiating control of phytophagous mites in July before the peak population period of September for Nigeria..