RESUMEN
Six biotypes of fungal isolates belonging to Ascosphaera apis were isolated by three media from infested honey bee larvae. Two isolates [A[7] and A[15]] were able to form sporocysts. However, the other four [A[3], A[4], A[8],A[9]] did not form sporocyts on cultivated Murashieg and Skoog medium [mMS]. Six isolates from symbiotic bacteria associated with midgut of honey bee workers have been insolated from healthy workers. Four isolates from endospore-forming bacteria belonged to Bacillus subtilis [B[2], B[4], B[10] and B[100]] and two isolates from non endospore-forming bacteria to Pseudomonas fluorescence [P[1[and P[5]] were isolated. Morphological features and physiological reactions of isolated bacteria were determined. Antagonistic effectiveness of both Bacillus subtilis and Pseudomonas fluorescence was tested against isolates of Ascosphaera apis, the causal pathogen of chalkbrood disease, in vitro. Data showed that Bacillus subtills isolate [B2], gave the highest antagonistic effect as inhibition zone and mycelial growth followed by Pseudomonas fluorescence [P[1]]. Highly significant differences among Bacillus subtilis [B[2]], Pseudomonas fluorescence [P[1]] and other bacterial strains were recorded.. Scanning electron microscope was used to examined the fungal hyphae and mature sporocysts of Ascosphaera apis which isolated from infested larvae and grown on [mMs]. Numerous distinguish differences were recorded. The examination showed that numerous bacterial cells of Pseudomonas fluorescence invaded fungal hyphae of Ascosphaera apis and caused disintegration the cell walls. Whereas Bacillus subtilis hyphae showed shrinking appearance. It could be conducted that such symbiotic bacteria can considered as a bioformula for controlling such disease in honey bee colonies