Abstract: Five types of fertilizers were applied to potato plant cultivation. Namely: compost banana, livestock`s manure, poultry wastes, urea and ammonium nitrate. The population densities of Phthorimaea operculella population infesting different fertilized potato cultivation were evaluated in both the field and the store. When the bioinsecticides Bacillus thuringiensis, Beauveria bassiana, Metarhizium anisopilae, margosan-O were added to the fertilizers during the fertilization periods; the densities of the potato tuber moth P. operculella were significantly reduced. Accordingly, spoiled potatoes were significantly decreased in the treated areas. The highest potatoes weights (399 and 439 kilos/fedan) were obtained when the fungus B. bassiana was mixed with compost banana fertilizer during season, 003 and 2004 season, respectively. Addition of other bioinsecticides to the fertilizers also showed different levels of reductions in the weight loss of the potato crop during both seasons.