الفهرس 
AcknowledgmentOnly 14 pages are availabe for public view
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Abstract
Sixty-two fungal isolates have been evaluated for their acaricidal activity against Tetranychus urticae. Among them, four fungal isolates have exhibited strong acaricidal potency. The culture filtrate of the isolates KF23, KF9, KF40 and KF45 showed mortality rates of 53.69%, 73.83%, 50.34% and 67.11% respectively. Morphological identification revealed that the isolates were Aspergillus melleus, Chaetomium globosum, Aspergillus terreus and Emericella nidulans. Subsequently, these isolates were subjected to further evaluation by screening of different concentrations of their ethyl acetate crude extracts against adult females and eggs of T. urticae and the median lethal concentration (LC50) was calculated. The LC50 values exhibited by A. melleus, C. globosum, A. terreus and E. nidulans were 10.27, 22.40, 33.05 and 14.68 mg/ml for adults, respectively. While LC50 values for eggs were 8.81, 11.05, 23.17 and 11.66 mg/ml, respectively. The most potent strain was A. melleus since it achieved the lowest LC50 value among the other strains. Identification of the selected strain was confirmed by means of DNA sequencing. Optimization of the secondary metabolites production by A. melleus revealed that highest number of secondary metabolites was obtained by incubating A. melleus for 6 days at 30⁰C, in media with initial pH 4. Purification of the active compounds of A. melleus by thin layer chromatography resulted in separation of five major bands at Rf values of Rf1 = 0.97, Rf2= 0.72, Rf3 = 0.55, Rf4 = 0.1 and Rf5 = 0.43. The concentration of LC50 of each band was subjected to screening against T. urticae and resulted in 28.52%, 10.07%, 57.05%, 8.39% and 11.74% mortality for Rf1, Rf2, Rf3, Rf4 and Rf5, respectively. The active compounds of the band appeared at Rf3 was separated by LCMS/MS. Out of thirteen compounds separated by LC/MS only five compounds were successfully identified are 7-oxocurvularin, nidulisporic, mellamide, ochratoxin C and 6-(4’-Hydroxy-2’-methyl phenoxy)-(–)-(3R)-mellein. For the entomopathogenic fungi, one entomogenous fungal isolate has been successfully isolated by insect bait method and identified as Purpureocilium lilacinum by morphological methods. Assay of conidial suspension of P. lilacinum revealed that the highest mortality rates achieved were 71.19 and 77.97% by concentrations of 5 and 1.6 , respectively at the 10th day after application. The evaluation of proteolytic and chitinolytic activity of P. lilacinum showed that its proteolytic activity was relatively higher than the chitinolytic activity since the protease showed a 25.8 mm clear zone after 10 days while the chitinase showed clear zone of 4.43 mm in diameter after the same time. Finally, crude extract of P. lilacinum was prepared and evaluated against both adult females and eggs of T. urticae. LC50 values were 30.75 mg/ml for adults and 10.49 mg/ml for eggs. from the obtained results, we can conclude that both of A. melleus and P. lilacinum could be used in bio-rationale control of T. urticae. Moreover, A. melleus could be a potential source of promising compounds that can be used in control of agricultural pests especially, T. urticae that needs further investigation such as formulation, their effect on non-target organisms as well as evaluating their activity under field and greenhouse conditions.