Fruit flies are serious pests of Mango in Sudan; they cause substantial damage to Mango production, both qualitatively and quantitatively. This study is an effort to establish information about the pest and, to test t...Fruit flies are serious pests of Mango in Sudan; they cause substantial damage to Mango production, both qualitatively and quantitatively. This study is an effort to establish information about the pest and, to test the susceptibility of some Mango cultivars （Baladi, Kitchener, Shendi, Alphons, Abu Samaka and Bit abusamaka） to the pest infestation. A survey was carded out at Shendi area, River Nile State, during the period of May 2007 to July 2008, using a home made trap resemble lvnfield traps with attractants （Methyl eugenol, Trimedlure, cue lure and Nu lure） to identify the fruit flies species found in the area and to study the seasonal abundance of the pest species and to determine the infestation percentage of different Mango cultivars. Results indicated that the fruit fly Bactrocera invadens is present all year-round in the study area, with population peak July to September. The study showed that Guava （ Psedium guajava ） represents the best alternative host for the pest. Abu samaka and Bit Abusa amaka mango cultivars were the most susceptible, with 100% infestation, followed by Shendi 70%, Kitchener 54%, Alphons and Baladi （30%, 28%, respectively） were the least susceptible. Also results revealed that females of both species Ceratitis cosyra and Bactrocera invadens out numbered males 4-5 times.展开更多
Human health has been potentially threatened by cadmium (Cd) contained in sewage irrigation water.Previous studies of Cd transport in soils were mainly conducted using small soil cores with pH values less than 6.The o...Human health has been potentially threatened by cadmium (Cd) contained in sewage irrigation water.Previous studies of Cd transport in soils were mainly conducted using small soil cores with pH values less than 6.The objectives of this study were to determine the parameters of the convection-dispersion equation (CDE) for Cd transport in relatively larger columns with neutral and alkaline soils,and to investigate the parameters' variability with depth.The soil columns were 50 cm in length and 12.5 cm in diameter.Ceramic suction lysimeters were buried at depths of 2.5,7.5,17.5,27.5,and 37.5 cm to abstract soil solution.Cd concentration in the soil solution samples were subsequently analyzed to obtain breakthrough curves (BTCs).Equilibrium and nonequilibrium models in CXTFIT program were used to estimate parameters of the CDE.The results suggested that both equilibrium and non-equilibrium models performed well in modeling Cd transport.The hydrodynamic dispersion coefficient (D) ranged from 0.18 to 10.70 cm 2 h 1,showing large differences among different depths.The retardation factor (R d) ranged from 25.4 to 54.7 and the standard deviation of R d value was lower than 30% of the mean value.Precipitation coefficient (R p) decreased consistently with increasing depth,varying from 1.000 × 10 10 to 0.661 h 1.Sensitivity tests showed that D was less sensitive than R d.These results would be helpful in understanding the transport and retention of Cd in non-acidic soils.展开更多
文摘Fruit flies are serious pests of Mango in Sudan; they cause substantial damage to Mango production, both qualitatively and quantitatively. This study is an effort to establish information about the pest and, to test the susceptibility of some Mango cultivars （Baladi, Kitchener, Shendi, Alphons, Abu Samaka and Bit abusamaka） to the pest infestation. A survey was carded out at Shendi area, River Nile State, during the period of May 2007 to July 2008, using a home made trap resemble lvnfield traps with attractants （Methyl eugenol, Trimedlure, cue lure and Nu lure） to identify the fruit flies species found in the area and to study the seasonal abundance of the pest species and to determine the infestation percentage of different Mango cultivars. Results indicated that the fruit fly Bactrocera invadens is present all year-round in the study area, with population peak July to September. The study showed that Guava （ Psedium guajava ） represents the best alternative host for the pest. Abu samaka and Bit Abusa amaka mango cultivars were the most susceptible, with 100% infestation, followed by Shendi 70%, Kitchener 54%, Alphons and Baladi （30%, 28%, respectively） were the least susceptible. Also results revealed that females of both species Ceratitis cosyra and Bactrocera invadens out numbered males 4-5 times.
基金Supported by the National Natural Science Foundation of China (No. 51179166)the National Basic Research Program(973 Program) of China (No. 2006CB403406)
文摘Human health has been potentially threatened by cadmium (Cd) contained in sewage irrigation water.Previous studies of Cd transport in soils were mainly conducted using small soil cores with pH values less than 6.The objectives of this study were to determine the parameters of the convection-dispersion equation (CDE) for Cd transport in relatively larger columns with neutral and alkaline soils,and to investigate the parameters' variability with depth.The soil columns were 50 cm in length and 12.5 cm in diameter.Ceramic suction lysimeters were buried at depths of 2.5,7.5,17.5,27.5,and 37.5 cm to abstract soil solution.Cd concentration in the soil solution samples were subsequently analyzed to obtain breakthrough curves (BTCs).Equilibrium and nonequilibrium models in CXTFIT program were used to estimate parameters of the CDE.The results suggested that both equilibrium and non-equilibrium models performed well in modeling Cd transport.The hydrodynamic dispersion coefficient (D) ranged from 0.18 to 10.70 cm 2 h 1,showing large differences among different depths.The retardation factor (R d) ranged from 25.4 to 54.7 and the standard deviation of R d value was lower than 30% of the mean value.Precipitation coefficient (R p) decreased consistently with increasing depth,varying from 1.000 × 10 10 to 0.661 h 1.Sensitivity tests showed that D was less sensitive than R d.These results would be helpful in understanding the transport and retention of Cd in non-acidic soils.
