球孢白僵菌菌种退化及其对马尾松毛虫防治的影响

球孢白僵菌继代培养中通过菌落局变产生不同类型分离株。本试验检测结果显示此类分离株多表现为产孢量下降、速率增加，毒力降低等与生产性善良爱化类似的变异现象，少数产孢量高，毒力强的分离株，因其生长速率慢即在培养中被掩盖而消失，并据此推断出继代培养次数对该菌退化速率的影响，提出了控制该菌菌种退化的有效措施。

Strain Degeneration of Beauveria Bassiana and Its EHect on Control of Pine Caterpillar,Dendrolimus Punctatus

The majority of segregants saltating during subculturing Beauveria bassianashowed decreased condiation as compared with accelerated vegetative growth rate and atten-uated virulence to pine caterpillar,Dendrolimus punctatus,being consistent with the degen-eration observed frequently in mass production of the fungus. Conidiation of a small portionof segregants was increased and their virulence was enhanced,but the growth of such segre-gants was usually enclosed and concealed by the degenerating segregants in mass productionbecause they grew more slowly.The above result suggested that the degeneration rate of thefungus was related to times of subculturing.Some effective measures for controling the de-generation were proposed.