A. A. Talebi, E. Rakhshani, S. E. Sadeghi, Y. Fathipour,
Volume 6, Issue 3 (10-2002)
Abstract
Fertility, developmental time and adult longevity of walnut aphid, Chromaphis juglandicola (Kalt.) and its parasitoid wasp, Trioxys pallidus (Hal.) were studied under controlled conditions with a constant temperature of 26±2oC, relative humidity of 60±5%, and 16:8 (L:D) photoperiod. Populations of walnut aphid and parasitoid wasp were reared on walnut seedling in a growth chamber. The mean developmental period, daily fertility rate, and progeny sex ratio were combined to construct demographic life tables. From these tables, intrinsic natural rate of increase (rm), net reproductive rate (R0) and mean generation time (Tc) were calculated. The net reproductive rate (female offsprings per female per generation) and intrinsic rate of natural increase values were 34.69 and 0.278 in walnut aphid and 53.85 and 0.385 in parasitoid, respectively. The mean generation time was 12.75 days in walnut aphid and 10.35 days in parasitoid. Values of rw (weekly multiplication of the females) indicates that T. pallidus is able to multiply 14.81 times per week, whereas the population of walnut aphid multiplies by only 7.001 times in the same period. The population of parasitoids doubled within 1.8 days while the aphid took 2.49 days. Mean pre-imaginal period was 9.14±0.34 days for male and 9.16±0.12 days for female parasitoids on a mixture of different nymphal stages of host. In walnut aphid it was 9.30±0.10 days. The pre-imaginal periods of parasitoid decreases as the aphid host ages. Longevity of adult male and female was 6.17±0.22 and 6.87±0.23 days, respectively, and 12.24±0.94 days for walnut aphid.
Y. Fathipour, A. Hosseini, A. A. Talebi, S. Moharramipour, Sh. Asgari,
Volume 9, Issue 2 (7-2005)
Abstract
The biological parameters of cabbage aphid, Brevicoryne brassicae (L.) was studied in the laboratory conditions under the three constant temperatures (20, 25 and 30 ºC), RH 60±5% and a photoperiod of 16:8 (L:D) using 40 first instar nymphs. Among nymphs, 40%, 55% and 10% of them completed their nymphal period in 20, 25 and 30 ºC, respectively and developed to adult stage. In 30 ºC, the most biological acitivities of aphid were disrupted and the most individuals (nymphs and adults) were killed. Most developmental periods, longevity and the amount of reproduction in 20 ºC were significantly greater than other temperatures. In temperatures 20, 25 and 30 ºC the last individual of a cohort died in age of 33, 29 and 16 days, respectively. The life expectancy of cabbage aphid in the first day of experiment was 13.93, 10.50 and 7.19, respectively according to the mentioned temperatures. There was a little difference between net reproduction rates in temperatures 20 and 25 ºC (16.74 and 15.92, respectively). Net reproduction rate was reduced extremely in temperature 30 ºC (1.75). The intrinsic rate of the increase in the temperatures 20, 25 and 30 ºC were 0.187, 0.226 and 0.042, respectively. The results indicated that 25 ºC was the optimal temperature for biological activities of B. brassicae and its highest population growth was observed at this temperature.
