Abstract
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.
Highlights
The two-spotted spider mite Tetranychus urticae Koch is one of the serious mite pests infesting pear trees
The present work introduces in detail the biology and life table of T. urticae when fed on the leaves of pear varieties Lacont and Hood under laboratory conditions at constant temperature at 15, 20, 25 and 30 °C and 70± 5% R.H
The effect of four constant temperature degrees (15, 20, 25 and 30 ̊C) on the biological aspects and demographic parameters (Ro, G, rm and exprm) of Tetranychus urticae Koch was studied in the laboratory under controlled condition ±2 ̊C and ± 5% R.H
Summary
The two-spotted spider mite Tetranychus urticae Koch is one of the serious mite pests infesting pear trees. The present work introduces in detail the biology and life table of T. urticae when fed on the leaves of pear varieties Lacont and Hood under laboratory conditions at constant temperature at 15 , 20 , 25 and 30 °C and 70± 5% R.H. MATERIAL AND METHODS To examine sex ratio of T. urticae, ten newly emerged females were placed and males were transferred and kept under the same conditions of temperature and R.H.
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