الفهرس 
LITERATURE REVIEWOnly 14 pages are availabe for public view
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Abstract
Schistocerca gregaria can change reversibly between the swarming gregarious phase and the cryptic solitarious phase. Gregarious S. gregaria, the most economic damaging phase, aggregate to form migrating swarms in nymph and in adult stages. In this thesis, Insect growth regulators (IGRs), alternative safe control agents, were evaluated. Their toxicity and morphogenetic disturbance on nymphs and adults were recorded. Influences of these IGRs on phase transient were also evaluated. The phenomena of gregarious-solitary-phase-interchange considered to be under specific genetic control; therefore, these genes may act as a new insect control approach and must be taken in highly consideration when synthesis of new controlling tools of S. gregaria. Quantitative and qualitative analysis of protein and DNA were measured.
The present investigation is subdivided into some main categories.
1. Toxicological and biological influences of IGRs.
Both diflubenzuron and pyriproxyfen induced positive influences in nymphal mortality of S. gregaria in the two extreme phases. However, they are different mode of action they induced highly significant negative influences on adult emergence (p<0.001). Conversely, there was a highly significant positive relationship between different concentrations and total inhibition, which was (89.5& 100%) for diflubenzuron but (82.2& 93.5%) for pyriproxyfen with gregarious and solitarious S. gregaria, respectively.
Furthermore, the application of both diflubenzuron and pyriproxyfen enhanced the morphogenetic abnormalities by increasing the concentrations. These morphogenetic abnormalities were observed in several categories (deformed wings, adhesive the old exuviae with any part of body and others).
Diflubenzuron has high efficiency on some biological aspects such as nymphal mortality, adult emergence, total inhibition, morphogenetic abnormalities of nymphs and adults. Likewise, pyriproxyfen has approximately the same efficiency.
Solitarious S. gregaria was more susceptible than the other extreme phases. This susceptibility was significant (p<0.001) in the adult emergence, the total inhibition, and in nymphal mortality, while non-significant (p>0.05) in morphogenetic abnormalities.
2. Effects of IGRs on phase polymorphism.
IGRs induced a non-significant (p>0.05) positive prolongation effect on the nymphal period. However, pyriproxyfen has a highly significant prolongation effect, especially with gregarious S. gregaria (p<0.001). In contrast, the two IGRs induced a significant reduction effect on the adult-longevity in both two extreme phases. However, diflubenzuron induced a highly significant reduction effect on the adult-longevity, especially with the solitarious S. gregaria. Furthermore, neither sexual maturation nor mating behavior was observed in females, which pretreated as 3rd instar nymphs with different concentrations of IGRs, as well as gregarious and solitarious S. gregaria, pretreated as adult-stage with LC50, which was (86.16 & 64) for diflubenzuron but (84.3 & 68.2) for pyriproxyfen with gregarious and solitarious S. gregaria, respectively .
Diflubenzuron and pyriproxyfen were unable to induce the appearance of the green solitarious body colour, while they enhanced the darkening pattern all over the body. It was concluded that both IGRs enhanced the transformation of some biological aspects of gregarious S. gregaria into solitarization behavior. However, they failed in the transformation of some phenotypic characters.
3. Phase polymorphism of S. gregaria.
This part is aiming to throw the light on gregarious-solitarious-phase-interchange as the second controlling agent of S. gregaria.
3.1. Solitarization of gregarious S. gregaria in the nymphal and adult stages.
With regard to the biological aspects, data recorded that the change of rearing density induced a highly significant prolongation effect on some biological aspects (p<0.001). This prolongation effect was observed directly in the 1st isolated generation, while it was the maximal level the 5th isolated generation. In contrast, the increasing number of instars was recorded only in the late isolated generations, 4th and 5th isolated generations.
Likewise, isolated the fresh molting gregarious S. gregaria for only one generation induced a prolongation effect. It was highly significant (p<0.001) in some characters while non-significant in some others (p>0.05). Consequently, isolation condition of gregarious S. gregaria in both nymphal and adult stages induced an appearance of the intermediate stage; therefore, the complete transformation of gregarious S. gregaria into solitarious phase needed more than one generation.
The complete transformation of body colour pigmentation into green solitarious was completed in the 3rd generation passing through successive degradation of the gregarious pigmentation. Isolation condition of the gregarious nymphs induced degradation of the black pattern them followed by degradation of the yellow background colour. In other words, gregarious nymphs lose the black patches then the te yellow colour. Furthermore, isolation of gregarious adult S. gregaria induced disappearance of the maturity colour as well as previous isolation condition induced appearance the green and the black hatchlings in their progeny.
3.2. Gregarization of solitarious S. gregaria.
3.2.1. Gregarization solitarious nymphs and adults S. gregaria: pigmentation and biological aspects.
Results demonstrated that the complete transformation of solitarious S. gregaria needed to three successive crowded generations. Crowded the 1st nymphs induced a highly significant reduction (p<0.001) of their biological aspects directly in the 1st crowded generation, which was increased during the successive crowded generations. Likewise, the reduction effect also was observed in the isolated fresh molting adults, which was significant (p<0.05) in some biological aspects but non-significant (p>0.05) in others.
With respect to pigmentation, the appearance of gregarious individuals is passing through three successive generations. First, the black patches were observed, followed by degradation of the green colour, which was replaced by the pale yellow colour in the 2nd generation; therefore, the normal gregarious nymphs were observed in the 3rd generation.
In contrast, the crowded condition of the fresh molting solitarious adults was unable to enhance any changes in their external feature in only one generation. However, this crowded condition induced appearance the green and the black hatchlings in their progeny.
3.2.2. Crowded both of solitarious and gregarious S. gregaria together: pigmentation and biological aspects.
This condition enhanced complete shifting of green solitarious nymphs into gregarious individuals only in one generation. This shifting was highly significant in both biological aspects and pigmentation of body colour. Likewise, crowding together both of solitarious and gregarious adults S. gregaria is successful in the complete shifting of the solitarious biological aspects into normal gregarious phase, while it is unable to enhance any changes in their external feature.
4. Biochemical responses of S. gregaria related to phase change.
Quantitative and qualitative analysis of total protein were carried out on the long-term gregarious S. gregaria and its 5 isolated generations.
4.1. Quantitative analysis of protein.
The obtained data declared that the isolation condition of the long-term gregarious S. gregaria induced a highly significant reduction (p<0.001) of total protein, compared with the long-term gregarious S. gregaria. The maximum reduction of the total protein was recorded in the 3rd isolated generation followed by relatively increase but in low level than the long-term gregarious S. gregaria.
4.2. Qualitative analysis of protein
The obtained data revealed that there are variations between protein profile in both two long-term extreme phases and their transient isolated generations. The detected variations were illustrated as follows:
According to molecular weights (Mw), the detected protein bands were separated into 52 bands. In the long-term gregarious S. gregaria, there were 8 detected bands with Mw (165.72 – 30.292) kDa. In contrast, the long-term isolated generation (5th isolated generation) had 12 detected protein bands with Mw (210.51–38.197) kDa. However, in the transient generations, the detected protein bands were 11, 8, 9 and 8, respectively, with the 1st, 2nd, 3rd, and 4th isolated generations. The most separated protein bands were detected in Mw ranging from 25 to 46 kDa.
5. Molecular responses of S. gregaria related to phase change.
Quantitative and qualitative analysis of total DNA were performed on the two extreme phases of S. gregaria) and the transient isolated generations.
5.1. Quantitative analysis of DNA.
Results demonstrated that the isolation condition induced a highly significant depression of total DNA levels (p<0.001). The total DNA levels were 7.7, 2.65, 1.63, 1.25, 2.25 and 4.4 µg/µl, respectively, with the long-term gregarious, 1st, 2nd, 3rd, 4th, and the long-term isolated generation. The maximum depression of DNA was recorded in both two transient generations, 2nd and 3rd isolated generations.
5.2. Qualitative analysis of DNA.
Data of this analysis demonstrated that each generation had a specific DNA profile. All detected variations of DNA profile were illustrated as follows:
Generally, 35 bands were detected in DNA profile, according to the (Mw). These bands were 6 in the long-term gregarious S. gregaria with Mw ranging from 366 to 3484 base pair (bp). However, the detected DNA bands in the transient generations (1st, 2nd, and 3rd isolated generations) exist in a constant number, which were 4 bands, while these constant bands differ in Mw and Rf. In contrast, the detected DNA bands increase in the late isolated stage 4th and 5th generations, which were 8 and 9 bands, respectively.
Furthermore, similarity index (SI) and genetic distance (Gd) values among long-term gregarious, 1st isolated generation, 2nd isolated generation, 3rd isolated generation, 4th isolated generation, and long-term solitarious samples using primer OPA-7 showed major DROP from 0.30, 0.30, 0.30, 0.29, to 0.13 between long-term gregarious sample and samples 1st isolated generation, 2nd isolated generation, 3rd isolated generation, 4th isolated generation, and long-term solitarious, respectively. This finding suggests major changes in DNA structure and sequence with the change from gregarious to solitarious phase.