竹卵圆蝽致病球孢白僵菌的分离和毒力测定

Isolation and Virulence of Beauveria bassiana Against Hippotiscus dorsalis

[目的]筛选对竹卵圆蝽若虫具有高毒力的致病球孢白僵菌菌株,为竹卵圆蝽的生物防治提供科学依据。[方法]采用组织分离法从竹卵圆蝽僵虫体内分离昆虫病原真菌,通过形态学、DNA条形码相结合的方法对病原真菌进行鉴定,采用生物测定法评价分离真菌菌株的毒力。[结果]从竹卵圆蝽僵虫体内获得7株病原真菌,这些菌株的形态特征、培养性状和ITS rDNA序列均与球孢白僵菌一致,因此,鉴定为球孢白僵菌。室内和林间生物测定结果表明,当分生孢子浓度为10^(8)孢子·mL^(-1)时,LYC10、LYC11、LYC15和LYC4菌株对竹卵圆蝽若虫的致死中时间LT_(50)分别为5.04、5.45、6.17和14.03 d;LYC11菌株林间的致死中浓度LC_(50)为2.43×10^(4)孢子·mL^(-1)。[结论]从竹卵圆蝽僵虫体内分离到7株球孢白僵菌,不同菌株的毒力存在差异,LYC10菌株的毒力最强;LYC11菌株林间的累计死亡率低于室内测定的结果。

[Objective]To select highly pathogenic strain of Beauveria bassiana against Hippotiscus dorsalis nymph,so as to support the biological control of H.dorsalis.[Method]The entomopathogenic fungi were isolated from muscardine cadaver of H.dorsalis with the tissue isolation approach.The species identification was conducted based on morphological method combined with DNA barcoding.The virulence of B.bassiana isolates was evaluated by bioassay.[Result]In the study,seven strains of entomopathogenic fungi were isolated from the muscardine cadaver of H.dorsalis.The morphological characteristics,cultural characteristics and ITS rDNA sequences of all isolates were consistent with those of B.bassiana,so these isolates were identified as B.bassiana.The results of bioassay in the laboratory showed that,when the conidia concentration was 10^(8)conidia·mL^(-1),the LT_(50)of LYC10,LYC11,LYC15 and LYC4 strains were 5.04 days,5.45 days,6.17 days and 14.03 days,respectively.In the field,the LC_(50)of LYC11 strain was 2.43×10^(4)conidia·mL^(-1).[Conclusion]In the study,seven strains of B.bassiana were isolated from H.dorsalis.It is showed the pathogenicity of different strains is different,and the pathogenicity of LYC10 strains is the strongest.The cumulative mortality of LYC11 strain in bamboo forest is lower than that measured in the laboratory.