Larvicidal efficacy of a new semi-synthetic avermectin derivative Methylamine avermectin (Radical 0.5% EC) was determined against larval instars of the Egyptian cotton leafworm, Spodoptera littoralis (Biosd.) in the laboratory, field and semi field experiments. 2 nd and 4 th instar larvae showed greatest susceptibility to the Radical in the laboratory experiment. The LC 50s values of the 2 nd and 4 th larval instar after 48 hours were 0.005 and 0.008 ppm, respectively. Radical was tested with recommended dosage (200 ml / 100 liter water) in field; it caused 84.6% reduction of pest population up to day 8 post-treatment. On the other hand, the semi field application of the same recommended dose on the 2 nd instar larvae showed general mean 73.6% mortality, 7 days after post-treatment. Also, some biochemical changed in the 4 th instar larvae after 48 hours of treatment with tested bioinsecticide were measured. It's clear from the results that activities of trehalase, invertase and acetylcholine esterase were increased in all treatments. Tested bioinsecticide reduced the activity of alkaline phosphatase at all doses compared to untreated larvae. No significant changes in acid-phosphatase activities were observed at all treatment doses. On studying the effect of esterases isozymes patterns, there were no differences in number and position of esterases isozymes between untreated and treated larvae in the whole larval body tissues although each band different in its concentration. The toxicity of the formulation to some beneficial predators was also evaluated in the field. There was no detectable effect of these bioinsecticide on naturally occurring beneficial species.
Under the laboratory conditions, toxicological evaluation of two compounds, Radiant SC 12% and Hexaflumuron (IGR) EC 10% against eggs of Pectinophora gossypiella (Saund.) and biological effect of these compounds on larvae, pupae and adult emergence resulted from treated eggs was also studied. The results revealed that LC 50s were 3.15, 0.811and 0.522 ppm., when one, two and prehatching days old eggs, respectively were treated with Radiant, while LC 50s were 3.754, 2.863 and 2.004 ppm, respectively for Hexaflumuron. The obtained results show a prolongation in larval and pupal developments resulted from treated eggs by Radiant, estimated by 20.8, 18.5 and 8.2 days, respectively for larvae and 8.9, 8.8 and 7.9 days for pupae. In case of Hexaflumuron, duration were 22.3, 20.6 and 20.4 days, respectively for larvae after egg treated and 10.8,10.0 and 11.3 days, respectively for pupae. In contrast, in adult stage, the results indicated high reduction in total eggs laid, percentage of hatchability and longevity.
The research presents a mathematical simulation of three kinds of pests and their predator for two plants: Cotton and broad bean. The study was applied in two regions in Egypt representing Upper Egypt and Delta. The study is based on similar field experimental results during the two successive years [2003][2004][2004][2005] in Qaha station-Qalubia governorate and seds station-Beni sweif governorate.Four models are introduced according to the plant and the geographical regions. The data were fitted to continuous curves to enable the process of predicting the number of each kind of the involved species. Many functions are suggested to describe the effect of temperature and relative humidity on population. However, for particular plant in particular area, only narrow ranges occur for both temperature and humidity. A process of smoothing the data was necessary to avoid the very extreme points of sudden increase (due to migration or eggs hatching) which can not be taken into account in a mathematical model. After smoothing the data, a least square method was used to fit the points to continuous curves. Then an algorithm has been made aiming to predict the number of the preys and predator at any time by knowing the initial state of each of them.The modeling for anticipating the expected number of spiders and preys for the different months was achieved using a Microsoft Visual Studio program. Four models are constructed and they have been shown to be easy for users. A calibration for the model was examined using a comparison study between field and model results, and a reasonable matching was observed.
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