The population density of the cowpea aphid, Aphis craccivora Koch. and its associated predators on faba bean and cowpea fields were studied at El-Khattara district, Sharkia Governorate, Egypt in 2010-2011 and 2011-2012 seasons. A. craccivora had three peaks on faba bean for each season the first peak was during the fourth week of December , the second one was in the second week of February, where the last peak was in the first week of March (2010-2011 season), The three peaks of 2011-2012 were recorded in the first week of January, the fourth week of February and the second week of March 2012. There was one peak only on cowpea in the third and fourth week of July in 2011 and 2012, respectively. The common predators observed in faba bean and cowpea fields were: Coccinella undecimpunctata L., Chrysoperla carnea Steph., Paederus alfierii (Koch.), Orius sp., Syrphus sp. Scymnus sp. and Cydonia vicina isis (Muls.) Regarding predators on faba bean, two peaks were found in the first weeks of February and second week of March (37 and 79 predators/ 100 plants) during the first season 2010-2011, also, two peaks were found in the third week of February and second week of March (61 and 58 predators / 100 plants), respectively in 2011-12 season.On cowpea, however, also two peaks were found in the fourth week of July and second week of August (89 and 69 predators/ 50 plants), respectively in 2011 season, while, one peak was found in the third week of July (78 predators/ 50 plants) in 2012.Statistical analysis showed that temperature and relative humidity had different effects (significant or insignificant) on insects under investigation.
Seasonal abundance of the oleander aphid, Aphis nerii Boyer de Fonscolombe and its associated parasitoids on duranta plants were studie in Zagazig and Mansoura during the three seasons 2004/05, 2005/06 and 2006/07. Obtained data revealed that: A. nerii infestation of duranta started by late September and early October, respectively. It continued to late March in the three season. The aphid numbers ranged between 10.88-48.04, 9.40-38.16 and 8.44-39.52 individuals/leaf, respectively in Zagazig during the three seasons. While, in Mansoura the infestation started earlier in the first half of September. It continued to early March. The aphid numbers ranged between 16.08-52.16, 15.72-37.56 and 14.00-41.00 individuals/leaf, respectively during the three seasons. In Zagazig, the aphid abundance showed three peaks in the three seasons of study. The mean numbers of aphids/leaf was 25.64, 25.04 and 22.75, respectively during the three seasons, meanwhile in Mansoura the aphid abundance showed three peaks in first season, four peaks in second season and two peaks in third seasons. The mean numbers of aphids/leaf were 26.63, 24.91 and 24.83, respectively during the three seasons. Five hymenopterous parasitoids, Diaeretiella rapae (M`Intosh), Aphidius sp. (Aphidiidae), (primary parasitoids) Pachyneuron sp. (Pteromalidae), Alloxysta sp. (Cynipidae) and Aphidencyrtus sp. (Encyrtidae) (Hyper parasitoids) were recorded..
Rate of parasitism by the aphid parasitoid, Diaeretiella rapae (M´ Intosh) on the cauliflower aphid, Brevicoryne brassicae L. as well the hyperparasitism on D. rapae were recorded, at Kafer Sakr district Sharkia Governorate during the two successive seasons 2010-11 and 2011-12. Total means of parasitism rates of D. rapae were 23.58 and 28.06 % during the two successive seasons, respectively. The parasitoid, D. rapae was parasitized by two hyperparasitism species Pachyneuron sp. and Alloxysta sp .The seasonal means of hyperparasitism percentage were 28.42 and 29.67% during period of study, respectively. The parasitoid density, in relation to that of host density, had influenced on percentage of parasitism. The highest percentage reached was 87.75% at 15 D. rapae female parasitoids per cage and the minimum was 46.1% at three female adult per cage. On the other hand, the average parasitism ratios in green houses were 73.
The study focuses on estimating thermodynamic characteristics at constant pressure for ambient air as a working fluid for gas turbines. The objective of this paper is to carry out a thermodynamic analysis of the properties of air as a working gas for a power plant. Various values of relative humidity, as well as temperatures, were examined in this study. Code was written using EES (Engineering Equations Solver) to conduct the simulation. This code contains the necessary equation to compute the thermodynamic characteristics of the working fluid. According to the results, both temperature and relative humidity remarkably influence the specific heat capacity (C_p), isentropic exponent (γ_h) as well as the gas constant of air (R_h). According to the results, when the ambient air temperature is increased from 0 to 45 ℃ with constant relative humidity values of either 10% or 90%, the specific heat capacity increases by 5.01% and 17.6%, respectively. Furthermore, the isentropic exponent decreases by 1.07% and 4.5%, respectively. The results show that the gas constant of air increases with ambient air temperature and relative humidity. One can conclude that the ambient conditions have considerable influence on the thermodynamic characteristics of a gas turbine working fluid.
This study was carried out to investigate the efficacy of four insecticides namely, kz oil, thiamethoxam, super-misrona oil and primiphosmethyl on the population of the cowpea aphid, A. craccivora Koch under laboratory and field conditions. Results showed that the mean numbers of the nymph and adult stages were irregularly decreased after treatment with all the examined insecticides. This decreasing lasted till the end of two weeks in case of kz oil, thiamethoxam, super-misrona and primiphosmethyl. The results revealed that primiphosmethyl proved to be the highest effective compound in the first and second seasons. On the other hand, thiamethoxam was the lowest effective one in both seasons. The other tested insecticides occupied intermediate positions between the highest and the lowest compounds. The tested insecticides could be descendingly arranged according to their reduction percentages in population as follows: primiphosmethyl > kz oil > super-misrona oil > thiamethoxam. The toxicity of the tested insecticides against the cowpea aphids under laboratory condations were studied. Results cleared that primiphosmethyl was the most toxic insecticide, whereas thiamethoxam was the lowest one causing 78.91, 83.97 and 50.70, 77.37% reduction in the first and second seasons, respectively. These insecticides, reached their maximum percent reduction in C. undecimpunctata population after the initial time of application. Meanwhile, the highest reduction percentage of C. carnea population was also detected after three days of treatment.
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