الفهرس 
Insecticidal and Biological Effect of Some Plant Extracts on the Cotton Leaf Worm, Spodoptera littoralisOnly 14 pages are availabe for public view
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Abstract
Insecticidal and Biological effect of Some plant Extracts on the cotton leaf worm Spodoptera littoralis
The aim of this study was to evaluate the activity of four plant leaves extractions, Citrus sinensis, Citrus reticulata, Citrus limon belong to family Rutacea and Mentha piperita belong to family Lamiace.
For this purpose the following points were studied:
1-Extraction of crude extracts & volatile oil.
2-Evaluation of toxicity of the extractions against the fourth instar larvae of Spodoptera littoralis.
3-Study their biological activity as promising materials.
4-Study the deformations occurred in the used insect during its life cycle.
The obtaind results could be summarized in the following:
Toxicological assay:
Testing the effect of the four plant extracts as stomach & contact poisons by two application methods, dipping technique and by topical application.
Results obtained from all plant extracts under investigation examined for their stomach or contact toxicity to the larvae of S.littoralis showed that the high mortality percentages were proportional to the concentration and time of exposure. In all experiment LC 50 & LC 90 as lethal concentrations values were determined by dipping and LD 50 & LD 90 as lethal does were also determined for all the plant extracts.
So, data showed that all plant extracts showed a lethal effect on 4th instar larvae of S. littoralis. Generally, all these extracts showed moderate mortality after 24 h and increased gradually within the second and third days, as they increased after 72 h of treatment. Data also revealed that decreasing the concentration of plant extracts lead to lowering the mortality percentage. The highest mortalities percent has caused by the treatment with the highest concentration.
By dipping the toxicity values based on LC50 values could be arranged in descending order as follows Mentha piperita v.o (4.8 ppm), Citrus sinensis C.E. (8.35 ppm), Mentha piperita C.E. (12.53 ppm), Citrus limoni C.E. (17.60 ppm) & Citrus reticulata C.E. come last recording LC50 value (25.51 ppm).
The slope values of the above mentioned plants varies between 0:7333±0.16 and 0.6.56±0.16 indicating that the response of the tested larvae all investigated plants was uniform.
Topically the most effective Mentha piperita C.E (4.5 ppm) followed by the volatile oil of the same plant,(4.8 ppm), Citrus limon C.E. (21.48 ppm), Citrus sinensis C.E. (22.48 ppm) them Citrus reticalata C.E. (53.047 ppm) the lowest effective plant Results. Cleared high slopes varied between (0.656±0.16) &(0.0835±0.16) indicating the uniform of response of all tested plants.