الفهرس 
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Abstract
Seed considers the basic and crucial input for agricultural production. Maintenance of high seed quality from harvest until planting is of almost importance in a seed production programme. During storage the quality of seeds get deteriorated in a number of ways of which infestation by the storage pests contribute a bulk share.
Callosobuchus maculatus is one of the most dangerous stores insects which causes a great damage for seeds of family Fabaceae such as cowpea, bean and others during the storage period. C. maculatus is known to resulted in 100% loss of stored cowpea. Various techniques and control methods depended heavily on the use of synthetic insecticides were used to control attack by insect pests. Due to increasing problems on insect resistance and impacts on non-target organisms, the research has been shifted towards using natural products in crop protection. Considering the factors discussed above; the present work was designed to evaluate the efficacy of three plant oils; Trigonella foenum-graecum (Fenugreek), Panax ginseng (Ginseng) and Origanum majorana (Marjoram) and the bio-insecticide abamectin (isolated from Streptomyces avermitilis). The effect of these natural product and their mixtures was studied on cowpea weevil; on mitotic division and chromosomes of plant seeds using chromosomal aberration assay. Cytological and molecular studies are necessary to obtain information regarding the effect of these materials on the genetic material of the stored seeds. Therefore, inter primer binding site (iPBS) assay that is based on LTR retrotransposons and serve as a general marker was also used to detect changes in DNA fingerprinting of the plant seeds exposed to tested materials. The result obtained are summarized as follows:
1- Toxicological effect of the tested oils and abamectin on Callosobruchus maculatus adult
The results showed that mortality percentage increase with the increase of rate of treatments (ml oils/kg seeds) and by increasing the time of exposure to oils or abamectin. The concentrations LC25, LC50, LC95 and LC99 were calculated for the tested materials and according to mortality of C. maculatus adults at LC95, the efficiency of the tested materials was arranged as follow abamectin > marjoram > fenugreek > ginseng.
2- Residual effect of the tested oils and abamectin on cowpea weevil at storage periods
The residual effect of the tested materials and their mixture on C. maculatus during storage periods (3 months) showed that abamectin was the most effective which caused complete mortality (100%) for adults till the end of the storage period, while sharply decreased with the three tested oils on mortality adults.
According to the adult emergence (F1), ginseng oil was the most effective oil that reduced adult emergence to 72.90% in the 5th week, followed by Marjoram oil then Fenugreek oil. On the other hand, LC95 abamectin and mixture 4 (LC20 abamectin - 2LC95 ginseng) caused complete reduction of adult emergence (F1) till the end of the storage period, followed by mixture 6 (LC20 abamectin - 2LC95 marjoram oil) which reduced emergence up to 94.57% then mixture 2 (LC20 abamectin-2LC95 fenugreek oil) which reduced adult emergence to 85.22%.
3. Effect of the tested material on germination and water absorbance of the stored seeds
All tested materials did not affect seed germination and water absorbance at both initial and after storage period. Mixture 2 reduced slightly the percentage of germination which was recorded 94 and 94.8% at the initial and after storage period respectively.
4- Effect of tested materials on mitotic index, percentage and type of abnormal mitosis.
In this part the cytological effect of tested materials was carried using Vicia faba root tips treated for 24 hours with the following concentrations:
- LC50, LC95, 2LC95 for fenugreek, ginseng and marjoram oils.
- LC20, LC50, LC95 of abamectin.
- Mixture 2 (LC20 abamectin - 2LC95 fenugreek oil)
- Mixture 4 (LC20 abamectin -2LC95 ginseng oil)
- Mixture 6 (LC20 abamectin - 2LC95 marjoram oil)
- Results showed that the frequencies of mitotic phases varied according to the treatments and the concentration applied.
- All roots treated with different treatments caused reduction in mitotic indices as compared with the untreated control and this reduction increased gradually by increasing the concentration. The bio-insecticide abamectin was the most effective on mitotic index as compared with the tested oils which was recorded 1.34% followed by marjoram oil (2.36%), ginseng (2.89%) then fenugreek oil (3.36%) in the roots treated with the concentration LC50, as compared with the negative control (4.18%). On the other hand, treatment of Vicia faba roots with each of mixutre 2, 4 and 6 lead to a significant reduction in mitotic index as compared with oils. Mitotic index in roots treated with mixture 2 showed slightly increase in MI as compared with that of LC20 abamectin which reflected the anti-mutagenic effect of fenugreek oil.
- The obtained results showed that all treatments induce different types of mitotic abnormalities in different mitotic stages and increased gradually with increasing the concentrations. Abnormalities appeared clearly in metaphase and ana-telophase while few number was observed in prophase. The most observed abnormalities were stickiness, C-metaphase, and disturbed chromosomes in metaphase and anaphase, bridges, laggards, micro-nucleated cells in addition to low percentage of chromosomal breakage.
5- Evaluation of toxic effect of tested materials on stored cowpea seed DNA fingerprinting using iPBS markers
To evaluate the potential of inter primer binding site (iPBS) assay that is serve as retro-marker; ten of universal primers that anneal to the conserved regions of retrotransposons was used. iPBS fingerprinting generated from the cowpea samples exposed to 2LC95 for each oil, LC95 abamectin, their mixtures and stored for 3 months, were clearly different from those obtained by control. The quantitative analysis of these bands was expressed as band loss and gain, as compared with the -ve control
- These primers showed polymorphism which ranged from 37.50% for the primer 2394 to 82.35 % with the primer 2270. Five primer of the 10 primer used showed six unique bands; four of them are positive unique bands.
- A maximum number of total gain and loss bands was recorded in samples treated with LC95 abamectin (29 bands) as compared with 26, 28 and 26 bands which were recorded with fenugreek, ginseng and marjoram respectively while, the highest number of loss and gain bands (37) in samples treated with the mixtures was recorded with mixture 4 as compared with 31 and 33 bands which recorded with mixture 2 and 6 respectively.
- GTS value of both fenugreek and marjoram recorded 70.79% while GTS value of sample treated with ginseng oil is 68.54%. Comparing GTS values of the three mixtures, it was found that the highest GTS value was recorded with mixture 2 followed by mixture 6 then mixture 4 which recorded 65.17, 62.93 and 58.43% respectively. These data showed that GTS values of sample treated with ginseng alone and its mixture with abamectin are recorded the lowest values between all treatments.
- Abamectin Band Sharing Index (BSI) showed lower percentage (0.82%) as compared with 0.84, 0.87 and 0.84% that recorded with fenugreek, ginseng and marjoram respectively. On the other hand, mixture 4 showed the lowest Band Sharing Index as compared with all treatments.
- The previous data showed that ginseng alone or its mixture with LC20 abamectin are the more effective in inducing changes on the DNA level of seed genome while fenugreek alone or its mixture with abemectin showed the lowest effect on seed genome as reflected by GTS values.