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【目的】松褐天牛Monochamus alternatus是我国松材线虫病Bursaphelenchus xylophilus的主要媒介昆虫。为了更好地开发利用松褐天牛病原微生物球孢白僵菌Beauveria bassiana,本研究通过航天搭载诱变及室内筛选,获得球孢白僵菌高毒力诱变菌株。【方法】将经神舟八号飞船航天搭载诱变后的孢子稀释液涂布在PDA平板上培养,获得单菌落菌株,进而筛选获得高毒力诱变菌株。观察所获9个航天诱变菌株的菌落形态、菌落生长速度、产孢量、孢子萌发率及抗高温胁迫能力等生物学特性,在此基础上筛选出生物学性状优良的菌株B159,B252和B305,并进一步对松褐天牛4龄幼虫进行生物测定。再通过撒菌粉和注射菌液方法,检验B252和B305对松木段内松褐天牛幼虫的杀虫效果。【结果】球孢白僵菌航天诱变菌株的生物学特性与野生型菌株cfcc81357存在分化。9个航天诱变菌株的菌落形态发生了不同程度的改变,6个菌落生长速率出现负向变异,仅诱变菌株B159,B252和B305能产生分生孢子。航天诱变菌株B252和B305在浓度为1.0×107cfu/m L时对松褐天牛4龄幼虫的校正死亡率均为100%,半致死中时(LT50)分别为8.08和8.56 d,明显优于野生型菌株,显示出对松褐天牛的极强毒力。使用撒菌粉和孢子液体注射方法,诱变菌株B252和B305对松木段内松褐天牛幼虫死亡率比野生型菌株高。【结论】诱变菌株B252和B305可能是优良菌株,对生物防治松褐天牛方面有潜在的实用价值。
【Objective】 Monochamus alternatus is the major vector insect of Bursaphelenchus xylophilus in China. In order to develop and utilize the Beauveria bassiana Beauveria bassiana, a pathogen of the brown cattle, the highly virulent strain of Beauveria bassiana was obtained by space-mount mutagenesis and indoor screening. 【Method】 Spore dilutions of mutagenized spirochetes which were carried by the space shuttle Shenzhou 8 were coated on PDA plates and cultured to obtain single-colony strains, and then screened to obtain highly virulent strains. The biological characteristics of colony morphology, colony growth rate, sporulation rate, spore germination rate and high temperature stress resistance of the nine mutagenized strains were observed. On this basis, the strains B159, B252 B305, and further bioassay the 4th instar larva of Monochamus alternatus. Then, the insecticidal effect of B252 and B305 on the Larvae of Monochamus alternatus in pine wood was tested by the methods of sprinkling the powder and injecting the bacteria liquid. 【Result】 The biological characteristics of the strain of Beauveria bassiana mutagenized with wild-type strain cfcc81357. The colony morphology of the 9 space mutagenic strains changed to some extent. The growth rate of 6 colonies showed negative variation. Only the mutants B159, B252 and B305 could produce conidia. The corrected mortalities of space-induced mutants B252 and B305 at the concentration of 1.0 × 107 cfu / m L were all 100% for the 4th instar larvae of Monochamus alternatus, and the median lethal doses (LT50) were 8.08 and 8.56 d respectively In wild-type strain, it shows strong virulence to Monochamus alternatus. The results showed that the mortality of B. alternatus adults in pine wood was higher than that of wild type by using the methods of liquid-in-place and spore liquid inoculation with strains B252 and B305. 【Conclusion】 Mutant strains B252 and B305 may be excellent strains, which have potential practical value in biological control of Monochamus alternatus.