| Two speices kinds of important entomopathogenic fungi Metarhizium anisopliae and Beauveria bassiana are widely applied to control pest in domestic and abroad. Generally they differentiate and develop a fine infection structure (appressorium) before penetrating the cuticle of host during infection procession. Appresspria as infectious structure of entomopathogenic fungi play key roles in pathogenicity by (a) secreting extracellular mucilaginous material; (b) producing several enzymes capable of attacking protein, chitin and lipid components of the cuticle of insect; (c) forming penetration peg or penetrant hyphae; (d) generating very high internal pressure inside the appressoria.In this paper, nutrients, microhabitats, physical and chemical factors such as carbon and nitrate element, temperature, relative huminity, pH, unsaturated fatty acid, extracts of cuticle of insect and substrata that influenced apprissorium formation of M. anisopliae CQMal02 and B. bassiana Bb07 were studied systematically in vitro in order to increase the ratio of appressorium formation, enhance the virulence against target insects and decrease the time of knockdown. These results provided detail knowledge for understanding molecular mechanism of appressorium formation, and will helpful to identify of virulent-related genes of insect pathogens and provided theoretical direction for screening recipe of fungi pesticide. The main results were as follows:1. Studies on polymorphism of appressoria of two speices kinds of entomopathogenic fungi through site-specific observation and photograph appressoria of CQMal02 and Bb07 in different environment and physical or chemical factors by digital-optical microscope. The results indicated the appressoria of CQMal 02 ranged from 1.7 to 14.9um in length and 2.54 to 8.5 um in width, and their shapes were found to be various such as spherical, elliptical, vesicular, clavate, capsular; the lengths and widths of appressoria of Bb07 ranged from 1.3 to 9.5 um and 1 to 2.5 um,respectively, most of which were spherical and vesicular, other shapes like clavate, capsular, elliptical also be found. Appressoria usually formed at the tip of monopolar germ tube or hyphae, but it also formed from one or two tips of dipolar germ tube even branched hyphae. Most of appressoria were melanization, produced penetration pegs, emerged hyphae or formed secondary appressoria with smaller pattern.2. Polyethylene Petri dish with diameter of 90mm was screened as hydrophobicsubstrata replacing cuticle of insect to induce appressorium formation. Appropriate nutrient solution and conidia of CQMa102 or Bb07 were inoculated in four Petri dishes, which were incubated 24 hours in different conditions, then every dish was observated four visual fields, and counted and statisticed germination of one hundred conidia and differentiation of one hundred germinal conidia. Optimal cultural condition for appressorium formation was screened by monofactorial experiment.Optimal cultural condition for appressorium formation of CQMal02 : nutrients was 0.0125% yeast extract medium, 1% subtracted sabourauds dextrose medium or 0.1% peptone medium; inoculation volume of 4ml; spore concentration of 106/ml; temprature was 25-26 C;pH6.0-7.0; full light; relative humidity was 99-100%. Optimal cultural condition for appressorium formation of Bb07: nutrients was 0.01% yeast extract medium or 1% subtracted sabourauds dextrose medium; inoculation volume of 3ml; spore concentration of 106/ml; temprature was 26+ 1 C; pH7.0-8.0; 12 hours light in late period.3. Based on optimal cultural condition screened for appressorium formation above, physical and chemical factors that influenced apprissorium formation of CQMa102 and Bb07 were tested.3.1 Physical factorsConidium suspension of CQMa102 and Bb07 were spreaded on surfaces of different substrata, which were then cultured on water agar medium for 24 hours. The data indicated the wings of locust and cicada were more suitable for appressorium formation than other substra...
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