الفهرس 
BacteriaOnly 14 pages are availabe for public view
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Abstract
The Egyptian cotton leaf worm S.littoralis is considered as a serious pest for many cultivated plants in Egypt. Recently, the control of this insects using microorganisms has a great attention. This method of control has no effect on the non- target organism, environmentally friendly and has low cost. The microorganisms include viruses, bacteria and fungi.
Twelve different bacterial strains were isolated from different habitats (soil, water and prawn exoskeletons. Preliminary study was done to investigate the insecticidal activity of bacterial isolates against 3rd instat larvae of S. littoralis using thin film technique. The filtrate of bacterial isolate 8 (BI8) elicited 100% larval mortality of S. littoralis. This isolate was identified by morphological, biochemical and molecular characteristics. The results clearly indicated that this strain was M. catahrralis (Moraxellacaea)
The effect of different concentrations of M. catahrralis filtrate on S. littoralis larvae was determined. The LC50 value of this filtrate was found to be 3.9x106 CFU/cm2 after 17h post treatment. At a concentration of 7.5x106 CFU/cm2, the LT50 value was 6.4h.
The optimum conditions for M. cataharrlis growth and insecticidal activity were investigated. It was found that optimum temperature and pH were 30ºC and 7.4, respectively. The most suitable carbon and nitrogen for M. cataharralis were beef extract and peptone respectively.
Incubation period has great effect on M. cataharralis growth and their insecticidal activity. The most optimum incubation period was found to be 48h.