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Background: Mosquitoes biolarvicides remain the most important method for mosquito control. The previous studies have shown Aspergillus sp.-expressed larvicidal properties against mosquito species. The present study evaluated larvicidal and histopathological effect of an endophytic fungus Aspergillus tamarii isolated from theCactus stem (Opuntia ficus-indica Mill). Method: The molecular identification of isolated A. tamarii was done by PCR amplification (5.8s rDNA) using a universal primer (ITS-1 and ITS-2). The secondary metabolites of A. tamarii was tested for larvicidal activity against Aedes aegypti and Culex quinquefasciatus. Larvicidal bioassay of different concentrations (- 100, 300, 500, 800 and 1000 μg/mL) isolated extracts were done according to the modified protocol. Each test included a set of control groups (i.e. DMSO and distilled water). The lethal concentrations (LC50 and LC90) were calculated by probit analysis. Experimental monitoring duration was 48 h. Results: The ethyl acetate extract from A. tamarii fungus resulted - excellent mosquitocidal effect against Ae. aegypti and Cx. quinquefasciatus mosquitoes, with least LC50 and LC90 values. -After 48 h, the Ae. aegypti expressed better results (LC50 = 29.10, 18.69, 16.76, 36.78 μg/mL and the LC90 = 45.59, 27.66, 27.50, 54.00 μg/mL) followed by Cx. quinquefaciatus (LC50 = 3.23, 24.99, 11.24, 10.95 μg/mL and the LC90 = 8.37, 8.29, 21.36, 20.28 μg/mL). The biochemical level of A. tamarii mycelium extract on both larvae was measured and the results shown a dose dependent activity on the level of AchE, α- and β-carboxylesterase assay. Gas Chromatography and Mass Spectroscopy (GC-MS) profile of A. tamarii extract reflected three compounds i.e. preg-4-en-3-one, 17. α-hydroxy-17. β-cyano- (7.39%), trans-3-undecene-1,5-diyne (45.77%) and pentane, 1,1,1,5-tetrachloro- (32.16%) which which might had attributed to larvae mortality. Conclusion: The findings of - present study shows that the use of endophytic A. tamarii fungal metabolites for control of dengue and filariasis vectors is promising and needs a semifield and small scale filed trials.