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Oligonychus psidium estebanes and baker (Acari: Tetranychidae): Population fluctuation and importance as occasional pest of guava crop, Psidium guajava L.

Abstract:

The population fluctuation of Oligonychus psidium was studied in relation with certain climatological conditions to report the importance of this species on guava orchards at Centro Frutícola del Zulia (CENFRUZU), Mara Co. (10°49'46,6° LN - 71°46'29,2° LW) and RFA, Baralt Co. (9°36'02° LN - 70°58'33° LW), Zulia State. From January to April of 2008, eight samplings of young and mature leaves, green fruits and portions of 5cm of productive branches were recollected; and mites were counted from 4096 samples at both localities. Populations of O. psidium damaged leaves and fruits at CENFRUZU and RFA. The highest populations of mites were present from January to February 2008 for CENFRUZU and from March to April 2008 for RFA. Means mite·plant -1 at CENFRUZU were higher than at RFA, which were significantly correlated to the relative humidity (73%, r=0.84) along with the absence of rains; whereas at RFA the HR (78%) showed a negative correlation with the mean mite·plant -1 (r=-0.83), along with the presence of rains from February to April (mean of 14mm), but no correlation was significantly observed. The wind speed was higher (P<0.05) (7.83 Km·h -1; r=-0.79) at CENFRUZU than at RFA (1.64 Km·h -1; r=0.76). Populations of O. psidium reached high peaks during the dry season at the beginning of 2008 in presence of winds of high speed, low relative humidity and absence of rains. Oligonychus psidium caused important damages to leaves and fruits becoming an occasional pest in CENFRUZU.