石斛象甲虫生真菌的分离鉴定及其毒力测定

Toxicity Test and Identification of the Entomogenous Fungi Isolated from the Weevil on the Dendrobium nobile

用石斛象甲上分离出来的两株蜡蚧轮枝菌菌株Ⅰ和菌株Ⅱ,采用Hall生物测定方法,测定了其致病性和对烟蚜的毒力。结果表明:在108孢子/ml浓度下,石斛象甲的喙、足在5d后有菌丝产生,8d后虫死亡,虫体表面布满菌丝。其中菌株Ⅰ致病性最强,其LC50在24～96h明显小于菌株Ⅱ;120h时,菌株Ⅰ的LC50为3.27×105孢子/ml,菌株Ⅱ的LC50为1.32×105孢子/ ml。在同一数量级（107、106、105）,菌株Ⅰ的LT50最短;两菌株在120h内都能使大量烟蚜感染致死,且随着孢子浓度的增加LT50都减小。研究表明从石斛象甲上分离出来的蜡蚧轮枝菌对石斛象甲具有致病性,对烟蚜有较高的生物活性。

The pathogenicity test to weevil and the toxicity test to Myzus persicae used two Verticillium lecanii isolated from weevil on the Dendrobium nobile,using the method described by Hall.The results showed:the consistency is 10~8 spore/ml,the weevil's haustellums and legs grow mycelium after 5 d,the insects died and it's surface covered with mycelium after 8 d,strainⅠis most pathogenicity in two strains,it's LC_(50) is lower than the strain 2 in the 24-96 h,the LC_(50) of the isolates 1 is 3.27×10~5 spore /ml and the strainⅡis 1.32×10~5 spore/ml,when the consistency is 10~5-10~7 spore/ml,the LT_(50) of strainⅠis shortest.Lots of M.persicae died in 120 h because of infected by the strains,the LT_(50) all reduces with the consistency increase.Research showed both strains have pathogenicity to weevil and high biology activities to M.persicae.