Document Type : Original Article
Authors
1
Plant Protection Res. Institute, Agricultural Research Center, Giza, Egypt
2
Plant Protection Dep., Fac. Agric., New Valley Univ., New Valley, Egypt
Abstract
The impact of temperature and some life table parameters of Rhopalosiphum padi (Linnaeus, 1758), were investigated at 18, 20, 22 and 24°C constant temperatures. The development durations decreased as the temperature increased, recorded 8.36, 7.65, 6.8 and 5.19 days at 18, 20, 22 and 24°C, respectively. The temperature threshold for the development of first, second, third and fourth instars and overall nymphal stage were 4.53, 7.96, 10.02, 9.67 and 8.25°C, respectively. The thermal units required for each nymphal instar; first, second, third and fourth and overall nymphal stages were 27.78, 21.28, 16.39, 22.22 and 83.33 day-degrees, respectively. The average adult fecundity was as high as 91.74 and 73.25 offspring at 20 and 22°C, but dropped to 47.66 and 63.45 offspring at 18 and 24°C. However, the average (mx) values per female/day were 2.24, 2.12, 1.93 and 1.01 offspring at 20, 24, 22 and 18°C, respectively. The highest net reproduction rates (R0) were 61.46 and 54.42 at 20 and 22°C, and mean generation time (T) and population doubling time (DT) diminished as temperature increased. The intrinsic rate of increase (rm= 0.3 and 0.25) and the finite rate of increase (λ= 1.36 and 1.29 nymphs/female/day) were greatest at 24 and 22°C, respectively. The results indicated clearly that temperatures from 20 to 24°C were in the favourable range for survival and reproduction of this serious pest.
Keywords
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