白僵菌菌种退化及其控制

以菌落局交作为球孢白僵菌菌种变异的标志，研究了２个野生型菌株及由其分离的８个单孢株在继代培养中的变异现象。同时探讨了８种培养基，６种氮源，１５种碳源，８种ｐＨ，不同温、湿度、先照平时菌种稳定性、产孢量、毒力的影响。结果显示：白僵菌的变异主要受控于菌株本身的遗传物质。常见的８种培养基以营养贫乏的ＰＤＡ、ＳＤＡ、ＣＭＡ最易发生变异，ＳＤＡＹ较稳定；氮源是影响菌落局变的最主要因子，在供试的６种氖源中，动物性氮源较植物性氮稳定，蛋白胨最优，植物性氮源中麦麸稳定性优于米糠、黄豆粉；碳源（除菊糖外）、Ｃ／Ｎ、ｐＨ对菌株稳定性影响不明显；低温、低湿、全光照下引起的变异最低。

Strain Degeneration and Its Control of Beauveria Bassiana

Variation in subculturing,2 wild type Beauveria bassiana strains and 8 single-spore isolates derived from them were studied with saltation as a estimate,Effects of 8 me-dia,15 carbohydrate sources,6 nitrogen sources,8 pH levels and different temperatures,il-luminations and relative humidities on strains stability,growth characters and virulence werealso obversed.The results suggested that the variation of B.bassiana was controlled by itsgenetic materials.Of the eight regular media,B,bassiana grew most stably on SDAY,butthose nutrition poor ones such as PDA,SDA,CAM caused variation very frequently.Nitro-gen source was the major factor for saltation.Among them,those from animal were morestable than those from plant,and peptone was the best one,Of those from plant,wheatbran was prior to rice bran and soybean powder.Influence of carbohydrate source,except forinulin,on strain stability was not obvious,and the lowest variation frequencies conincidedwith low temperature,low relative humidity and full illumination.