Effect of Temperature Degrees on the Biology and Life Table Parameters of Tetranychus urticae Koch on Two Pear varieties

Document Type : Original Article


Fruit Acarology Dept., PPRI, Agric. Res. Center, Dokki, Giza, Egypt.Giza, Egypt.


Developmental times and reproduction rates of the two-spotted spider mite Tetranychus urticae Koch were studied when fed on leaves of two pear varieties (i.e. Lacont and Hood varieties) under laboratory conditions of 15, 20, 25 & 30 ± 2°C, 70% ± 5% RH. The longest developmental stages reached 30.6 and 30.1 days for female and male at 15°C when the T. urticae was fed on Lacont pear variety, while when reared on Hood pear variety it was 34 and 32.1 days at the same temperature. The highest total mean fecundity rate was recorded at 30oC (156.8 and 143.6 eggs /female). Sex ratio was affected by temperature as proportion of female increased. In addition, the values of rm and λ increased with temperature increase, while mean generation time (T) and generation doubling time (DT) values decreased with temperature increase, thus the reproduction of mites increased. This mite favored high temperature. The Lacont pear variety was more favored to this mite.