Effect of temperature degrees on the duration of the phytophagous mite, Eutetranychus orientalis complex (klein) (acari: Tetranychidae) when fed on green bean (Phaseolus vulgaris L.)

Abstract

Spider mites (Acari: Tetranychidae) are the most important phytophagous mite pests of agricultural crops over the worldwide. This study aims to study the effect of different temperature degrees on the developmental stages of the phytophagous mite Eutetranychus orientalis complex (Klein) on some vegetable crops and to predict the population according to the prevailing temperature. Development times of the Eutetranychus orientalis complex (Klein) were evaluated in the laboratory on excised leaf disc of (green bean) Phaseolus vulgarisL at various degrees of temperature (20, 25 and 30±2 °C) with 60±5% relative humidity (RH)under laboratory conditions. Total development times from egg to adult stage were 26.37±1.28 and 24.24±0.92 days at 20±2 °C, 21.25±1.23 and 18.99±1.28 days at 25±2 °C and 11.48±1.07 and 9.88±1.16 at 30±2 °C for female and male respectively. The pre-ovipositionperiod, oviposition period and post-oviposition period were 4.96±1.44, 8.13±2.22 and 4.87±1.23 days at 20±2 °C,1.46±0.35, 6.73±0.82 and 1.99±0.79 days at 25±2 °C and 1.04±0.27, 6.20±0.87 and 1.67±0.40 days respectively at 30±2 °C. Total eggs laid by mite were found to reach the maximum limit at 30±2 °C (22.60 ± 3.63 eggs/mite) followed by 25±2 °C (16.44 ± 3.87 eggs/mite) and 20±2 °C (3.14 ± 2.56 eggs/mite). In conclusion, the time required for female life cycle, longevity and life span was longer than the male at different tested temperature degrees and the differences were significant and the 20±2°C gave the longest life cycle, while the temperature of 30±2°C gave the shortest life cycle.