Showing 4 results for Y. Fathipour
A. A. Talebi, E. Rakhshani, S. E. Sadeghi, Y. Fathipour,
Volume 6, Issue 3 (fall 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.
M. A. Samia, K. Kamali, A. A. Talebi, Y. Fathipour,
Volume 7, Issue 4 (winter 2004)
Abstract
The population parameters of sweet potato white fly, Bemisia tabaci (Genn.) (Hom.: Aleyrodidae), which is an important pest of cotton fields, were studied during 2001. The infected leaves containing nymphs and pupae were collected from Darab, Qom, Saveh, Gonbad, Gorgan, Varamin, Garmsar, Orsoiieh (Kerman), and Shooshtar cotton fields. Experiments were conducted in a growth chamber under 24±.2ºC, 55%±3RH and 16:8 (L:D) photoperiod on cotton, a Gossypium hirsutum L. (Varamin 76 variety). The newly emerged populations of each locality were released into a large cage set on cotton plants separately. Population parameters of 40 mated females were calculated for each local population. Intrinsic rates of increase (r) for Darab, Qom, Saveh, Gonbad, Gorgan, Varamin, Garmsar, Orsoiieh and Shooshtar were 0.0401, 0.0719, 0.0750, 0.0602, .0682, 0.0774, 0.0876, 0.0751 and 0.0988, respectively. Doubling times (DT) were 17.26, 9.63, 9.24, 11.51, 10.16, 8.94, 7.91, 9.22 and 7.083 days, respectively, and mean generation times (Tc) were calculated to be 28.72, 28.9, 28.74, 28.3, 28.68, 27.53, 29.12, 28.21 and 26.84 days, respectively. Other population parameters such as finite rate of increase (λ), intrinsic birth rate (b), intrinsic death rate (d), and stable age distribution were also calculated. The results revealed that there were significant differences between population parameters in local populations. The parameter (r) was the least in Darab and the greatest in Shooshtar populations.
H. M. Takalloozadeh, K. Kamali, A. Talebi, Y. Fathipour,
Volume 7, Issue 4 (winter 2004)
Abstract
The host-stage preferences of alfalfa black aphid, Aphis craccivora, by parasitoid wasp, Lysiphlebus fabarum, were studied under two trials under growth chamber conditions (55±5 %, R. H., L:D 14:10 H. and Tem. 20 ±2° C ). In the first trial, all stages of aphid in equal ratios, and in the second trial, variable ratios of 5:15, 15:15 and 15:5 of 3rd and 4th instar nymphs were used for parasitisation. The objective was to identify the most preferred stage of aphid for parasitism by Lysiphlebus fabarum. The results showed that 3rd instar nymphs of alfalfa black aphid were the most preferred stage with 38.75% of parasitism. Whereas 4th instar nymphs and adults had 23.75% and 21.25% parasitism, respectively. The first instar nymphs were not parasitized at all. In the second trial with variable ratios of 3rd and 4th instars of alfalfa black aphid, parasitism of 3rd instar in ratios 25, 50 and 75 percent of total population were 35.9, 55.74 and 79.6%, respectively, while those for 4th instar nymphs were 20.36, 44.26 and 64.09%, respectively. So there was a positive preference for 3rd instar and a negative preference for 4th instar nymphs.
Y. Fathipour, A. Hosseini, A. A. Talebi, S. Moharramipour, Sh. Asgari,
Volume 9, Issue 2 (summer 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.
