Seasonal population dynamics of the two-spotted spider mite, Tetranychus urticae koch (Acari: Tetranychidae) under acaricide constraint on eggplant in Bursa Province (Turkey)

Abstract

The distribution and population dynamics of the Two-spotted spider mite, Tetranychus urticae Koch (Acari: Tetranychidae) were investigated in the sprayed eggplant fields of Bursa Province in the north-western region of Turkey. At 10 days interval, fifty eggplant 'cv. Yalova 49' leaves per field were removed randomly from the three commercial fields during 1999-2000. T. urticae was the only damaging species of Tetranychid found, and Amblyseius bicaudus (Wainstein) the only phytoseiid present in these fields. A. bicaudus abundance had significant correlation and synchrony with population densities of T. urticae (P<0.05). The activity of females of T. urticae was first recorded on various weeds at the end of March and February in 1999 and 2000, respectively, but the mites appeared on eggplant fields in early June and late May in the same years, respectively. The population of T. urticae peaked twice in both years and the first peak occurred from late June to late August and the second was observed from late September to late October. The occurrence of mites on the eggplants ended in early or mid November when the eggplant fields were mowed, although all stages of T. urticae were observed on these fields at this time. T. urticae population was positively correlated with mean temperature (r = 0.660 to 0.678, P < 0.05), while negative relationship was found between mean humidity and mite population (r = 0.653 to 0.674, P<0.05).