Developmental periods, adult longevity and thermal requirements of Diaeretiella rapae (M'Intosh) were investigated at 18, 20, 22 and 24°C constant temperature. The development durations decreased as the temperature increased. At 24°C and 18°C the periods for egg-mummy period was 8.85 days and 12.79 days; the mummy-adult period was 5.29 days and 7.31 days; the egg-adult period was 14.14 days and 20.10 days; and for the adult longevity was 3.22 days and 4.69 days. The rate of development of all stages increased as the temperature increased from 18 to 24°C. The developmental threshold of D. rapae estimated using linear regression was 4.5, 2.33, 3.75 and 4.87, while the mean thermal units were 166.8, 117.03, 282.53 and 64.51 for egg-mummy period, mummy-adult period, egg-adult period and adult longevity, respectively. Results revealed that the optimal temperature for growth population of D. rapae ranged from 18 to 20°C.
Key words: Diaeretiella rapae, Rhopalosiphum padi, biological aspects, Temperatures