Abstract Brown mite, Bryobia rubrioculusScheuten, is one of the most important pests of apple trees in western Iran. Development and fecundity of this mite were studied on apple at five constant temperatures (20, 22.5, 25, 27.5 and 30°C), 60 ± 5% RH and a photoperiod of 16:8 h (L: D). The developmental time of immature stages ranged from 39.65 ± 0.96 days at 20°C to 18.18 ± 0.47 days at 30°C. The lower temperature threshold (t) and thermal constant (k) of the immature stages were estimated to be 12.9°C and 279.7 degree days (DD), respectively. The average adult longevity of females was determined to be 16.75 ± 1.14 days at 20°C to 8.58 ± 0.38 days at 30°C. The highest and lowest mean number of eggs per female during adult life was 4.79 ± 1.36 and 3.75 ± 1.49 at 30 and 20°C, respectively. The results of this study can be used to predict the development and population dynamics of B. rubrioculus.
