الفهرس 
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Abstract
The aim of the present study is detection ; isolation and identification of SpliNPV Egyptian isolate or isolates on the basis of pathogenicity, biological, morphological, histological and molecular characters as well as bioinformatics analysis. br Two viral isolates of Spodoptera littoralis (Boisd.) nuclear polyhedrosis virus were collected, -#102;-#114;-#111;-#109; biological control unit, plant protection research institute, Agric. research center, and moribund or recently dead larvae which showing different external viral like symptoms during the rearing of insect in insect virus lab, department of microbiology, Fac. of Agric., Ain Shams Univ. The virus isolated and stained by Gemisa stained and examined under light microscope with an oil immersion objective. br The number of polyhedra inclusion bodies (PIBs) in one ml of the suspension was determined by means of the haemocytometer slide. br The pathogenicity of SpliNPV isolate was identified by biological characters through applying different concentrations of virus on S.littoralis.The SpliNPV concentrations give 100% mortality to second , third and forth instar S.littoralis larvae.The LC50 for different instars ranged -#102;-#114;-#111;-#109; 0.4x105 , 0.2 x105 , 0.6 x105 and 0.3x105 , 0.1 x105 , 0.4x105 for isolate 1 and 2 respectively. The third instar was more Susceptible than the second and forth instar larvae. br SpliNPV Showed different symptoms throughout the infection period indicated the infectivity progression of virus , these symptoms were :- slow motion of larvae , red color on the cuticle , swelling of the larval body and fragile epidermis. br SpliNPV was identified by morphological and histological characters through examination the external effect of virus on the larval body. br Light micrographs of semi-thin section figured out several histological changes , due to the activity of the virus , there is hyper-proliferation of the epithelial cells make the peritrophic membrane appear voluminous , as well as the pathogenic effect of virus damage all epithelial cells ,destruct all internal organs of the midgut include basement and peritrophic membrane , also spread the infection of virus throughout the midgut lead to formation of small empty vacuoles. br The polyhedra were examined by SEM which showed it at power magnification 5000X. we also studied the effect of temperature on the activity of virus , we showed that the increased of temperature up to 35ºC decreased the activity of virus and increased in the temperature of incubation , increased the activity of virus then the viral activity decreased. br Also , SpliNPV was tested for it’s ability to transmission the virus via eggs , pupae and adults, we showed that the virus could transmission to the newly hatched larvae when eggs and adults exposed to the virus but, the pupae could not transmission the virus to the newly hatched larvae. br After that we studied how improving the virus production , by using two technique :The high larval density method reared on a semi-synthetic diet and High larval density reared on castor oil leaves , we noticed that the production of virus increased when larvae were reared on castor oil leaves. br We also studied the Activity of Nuclear polyhedrosis virus of the cotton leafworm evaluated at two different treatments with diet:- br In the first, the NPV dose was mixed with the artificial diet, In the second the surface contaminated diet , the % mortality of larvae was higher in the second technique than the first technique. br Some of the important ones that inhibit their commercial development as a microbial pesticides include : rapid inactivation of the virus by sunlight or ultraviolet (UV) light. It was suggested that the inactivation of baculoviruses by UV -#102;-#114;-#111;-#109; sunlight could result -#102;-#114;-#111;-#109; UV-generated reactive oxygen species such as peroxides , single oxygen , or hydroxyl radicals (free radicals). br However, these reactive oxygen species could only be partially neutralized by oxidative enzymes (Catalase, peroxides and antioxidants), thus preventing deterioration of viruses activity, so that the effect of UV on cotton leafworm Spodoptera littoralis (SpliNPV) in Egypt was investigated. When SpliNPV was exposed to UV source for 0 , 5 , 10 , 15, 30 , 60 , 120 , 180 , 240 , 300 minutes , more than 90 % inactivation was a achieved after 30 minutes. A complete inactivation occurred after 60 minutes. So that , nine plant additives containing different groups of antioxidants were tested as UV – protectant additives for SpliNPV suspension , to prolong the virus activity .The results were based on bioassays , to test originally activity remaining ( OAR) of the virus after exposure to UV source. The results showed that,% OAR of virus alone was 5.25 % , while the % OAR of the virus treated with Green Tea , Guava leaves, Mango leaves and Basil additives gave the lowest protection 55.88 , 75.76 , 77.07 and 81.92 % respectively . br The Pepper and the Green Cabbage treatments gave the mediated protection 84.04 and 84.85 % OAR respectively, while the Black Tea , Dill and Peppermint gave the best results 97.37, 96.16 and 97.07 % OAR respectively . Second screening was made to compare additives that gave the best results after 5 hours exposure to UV irradiation. br The obtained result demonstrated that Black tea and Peppermint additives gave the higher rates of virus persistence than Dill . br Also , the SpliNPV isolates were identified by molecular characters, -#119;-#104;-#101;-#114;-#101; total DNA was extracted -#102;-#114;-#111;-#109; infected S.littoralis with SpliNPV . PCR technique was used to amplify a fragment of polyhedron gene.