Showing 7 results for A. Talebi
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.
M. Vatankhah, M. A. Talebi, M. A. Edris,
Volume 11, Issue 41 (fall 2007)
Abstract
In this study 5025 records from the Lori-Bakhtiari sheep stud were used to predict phenotypic, genetic and environmental change in ewe traits from 1989 to 2004. Best linear unbiased prediction (BLUP) of breeding values were estimated by Drivative Free Restricted Maximum Likelihood (DFREML) procedure using single and multi-trait animal model. Phenotypic, genetic and environmental trends were calculated by regressing of the average phenotypic values, predicted breeding values and environmental values in the year of ewe birth respectively. The estimated phenotypic trends were –0.1223 kg for ewe body weight, -0.0415 kg for greasy fleece weight, 0.6639% for conception rate, 0.0003 for number of lambs born per ewe lambing, 0.0094 for number of lambs weaned per ewe lambing, 0.0380 kg for total birth weight per ewe exposed and 0.4227 kg for total weaning weight per ewe exposed. The estimated genetic trends were 0.0603 kg, -0.0004 kg, 0.0183%, -0.0012, -0.0007, 0.0030 kg and 0.0211 kg from single trait analysis and 0.0549 kg, -0.0006 kg, 0.0089%, -0.0008, -0.0008, 0.0030 kg and 0.0230 kg respectively from multi-trait analysis. The estimated phenotypic and environmental trends were significant but genetic trends were not significant (P<0.05) for often traits.
A. Talebi, A. H. Charkhabi, H. R. Peyrowan, A. A. Hashemi, H. Mosaddegh,
Volume 16, Issue 62 (Winte - 2013 2013)
Abstract
The Marls are unstable sedimentary formations that contain chemical materials and destructive particles. Marls Erosion processes are very intensive, so different forms of erosion on the marls as badlands are of specific characteristics in marl lands. Hence, recognition of effective characteristics in marls erodibility is necessary to adopt corrective measures and methods. In this research, for assessing marls erodibility in Hablehroud watershed portable rain simulator was used. Runoff and sediment amounts were measured in each marl unit. Then effective Factors were identified using statistical parameters. Finally, by factor analysis we determined the relationship between marls chemical properties and sediment yield. Therefore, effective parameters of erosion and sediment yield were determined. Results showed sediment yield is decreased in gypsum marl, sandy marl, salt marl and limy marl. In addition, erosion and sediment yield are increased with increasing EC, Na, Cl, SAR and with decreasing TNV, HCO3
A. Talebi, Z. Akbari,
Volume 17, Issue 63 (Spring 2013)
Abstract
The real estimation of the volume of sediments carried by rivers in water projects is very important. In fact, achieving the most important ways to calculate sediment discharge has been considered as the objective of the most research projects. Among these methods, the machine learning methods such as decision trees model (that are based on the principles of learning) can be presented. Decision tree method is a hierarchical multi step method which is a recursive data collection technique to binary and smaller sub-divisions until the final analysis cannot be divided. Decision trees consider a priori known set of data and derive a decision tree from it. Then, tree can be used as the set of laws to predict unknown features. In this research, the efficiency of this technique for predicting the suspended sediments in Ilam dam basin has been investigated. To evaluate the accuracy of the methods (written by MATLAB software), statistical criteria such as R, BIAS, RMSE, r2 and MAE were computed. The results showed that based on all the statistical criteria, decision tree in comparison with the sediment rating curve had most consistency with the observed data. Meanwhile, the most important factors for creating tree in the model (that had high correlation with sediment data) are the corresponding discharge and daily rainfall.
