马铃薯叶片内生细菌的分离鉴定及其对马铃薯块茎蛾的毒力研究

Isolation and identification of endophytic bacteria in potato leaves and their virulence to Phthorimaea operculella

  • 摘要: 【目的】研究马铃薯叶片内生细菌对马铃薯块茎蛾幼虫的杀虫活性,为马铃薯块茎蛾生物防治提供理论依据。【方法】以云南省2种马铃薯主栽品种丽薯6号和会-2叶片为材料,采用LB固体培养基分离培养马铃薯叶片内生细菌,根据内生细菌的形态特征和16S rDNA序列进行种类鉴定;通过浸叶饲喂法测定内生细菌的发酵液、发酵上清液和菌悬液对马铃薯块茎蛾3龄幼虫的毒力。【结果】分别从丽薯6号和会-2叶片中分离获得对马铃薯块茎蛾3龄幼虫具有杀虫活性的苏云金芽孢杆菌(Bacillus thuringiensis)QL1和带化红球菌(Rhodococcus fascians)YH2。分别用浓度为1.5×109CFU/mL的菌株QL1和YH2发酵液饲喂马铃薯块茎蛾3龄幼虫后第7 d时,其幼虫累积死亡率分别为81.67%和65.00%,LT50分别为3.03和5.58 d;菌株QL1发酵液处理后第3、5和7 d马铃薯块茎蛾3龄幼虫的LC50分别为7.99×108、3.21×106和2.73×103CFU/mL;菌株YH2菌体无明显致死效应。在1.5×109CFU/mL浓度下,菌株QL1和YH2发酵液对马铃薯块茎蛾3龄幼虫的杀虫活性高于发酵上清液和菌悬液。菌株QL1和YH2的发酵液、发酵上清液、菌悬液处理后马铃薯块茎蛾3龄幼虫的累积死亡率均随着处理时间变长而逐渐升高。【结论】马铃薯叶片内生细菌苏云金芽孢杆菌菌株QL1和带化红球菌菌株YH2的发酵液、发酵上清液、菌悬液对马铃薯块茎蛾3龄幼虫均具有杀虫活性,可作为马铃薯块茎蛾生防制剂开发的潜力菌株。

     

    Abstract: 【Objective】To study insecticidal activity of endophytic bacteria in potato leaves against Phthorimaea operculella larvae,and to provide theoretical basis for biological control of P. operculella.【Method】Leaves of 2 main potato varieties Lishu No.6 and Hui-2 in Yunnan Province were used as materials. Endophytic bacteria in the potato leaves were isolated and cultured on LB solid medium. Species of endophytic bacteria were identified based on the morphological characteristics and 16S rDNA sequence. Virulence of fermentation broth,fermentation supernatant and bacterial suspension to the 3rd instar larvae of P. operculella were determined by leaf immersion feeding method.【Result】Bacillus thuringiensis QL1 and Rhodococcus fascians YH2 with insecticidal activity against P. operculella 3rd instar larvae were isolated from the leaves of the Lishu No.6 and Hui-2,respectively. P. operculella 3rd instar larvae were treated with strains QL1 and YH2 fermentation broth at 1.5×109 CFU/mL on the 7th day,and the cumulative mortality rates were 81.67% and 65.00%,and the LT50were 3.03 and 5.58 d,respectively. P. operculella 3rd instar larvae treated with strain QL1 fermentation broth at the 3rd,5th and 7th d,and their LC50were 7.99×108,3.21×106 and 2.73×103 CFU/mL,respectively. The strain YH2 bacteria did not obviously affect mortality of P. operculella 3rd instar larvae. At 1.5×109 CFU/mL,insecticidal activity against P. operculella 3rd instar larvae of strains QL1 and YH2 fermentation broth were stronger than of fermentation supernatant and bacterial suspension. Furthermore,as time went on,the cumulative mortality rates increased gradually after P. operculella 3rd instar larvae were treated with strains QL1 and YH2 fermentation broth,fermentation supernatant and bacterial suspension.【Conclusion】Fermentation broth,fermentation supernatant and bacterial suspension of strains B. thuringiensis QL1 and R. fascians YH2 from endophytic bacteria in potato leaves have insecticidal activity against the 3rd instar larvae of P. operculella,therefore,they can be developed as potential strains of the P. operculella biological control agent.

     

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