亚洲玉米螟越冬后幼虫致病细菌——黏质沙雷氏菌的分离鉴定及杀虫活性评价

Isolation,Identification and Evaluation of Insecticidal Activity of an Entomopathogenic Bacteria Strain Infecting Post-overwintering Ostrinia furnacalis Larvae

本研究从新疆伊犁河谷新源县春播玉米田越冬后自然罹病亚洲玉米螟幼虫上分离获得1株细菌菌株ACB3014,通过形态学观察、生理生化特性及16S rDNA序列分析对该菌株进行了鉴定,并采用饲喂法测定了该菌株对亚洲玉米螟3龄幼虫的致病性。结果表明菌株ACB3014为黏质沙雷氏菌Serratia marcescens。菌株ACB3014对亚洲玉米螟3龄幼虫的累积校正死亡率随菌悬液浓度的升高而增加。饲喂ACB3014菌悬液后第7 d,在浓度2×10^(4)~2×10^(8)cfu/mL下,亚洲玉米螟3龄幼虫的累积校正死亡率为27.78%~77.78%。接种第13 d,亚洲玉米螟3龄幼虫LC_(50)为3.79×10^(3)cfu/mL,当浓度达2×10^(8)cfu/mL时,LT_(50)为3.93 d。且染病后的亚洲玉米螟体色为暗红色和黑色,虫体呈脓状溃烂,散发出强烈异味。综上,黏质沙雷氏菌ACB3014菌株对亚洲玉米螟幼虫有很好的杀虫活性,具有很高的防治潜力,可用作亚洲玉米螟的绿色生物防治资源。

A bacterial strain ACB3014 was isolated from the infected overwintering larvae of Ostrinia furnacalis in spring sown corn fields in Xinyuan County,Yili Valley,Xinjiang and identified by morphological observation,physiological and biochemical characteristics and 16S rDNA sequence analysis.The pathogenicity of this strain against the 3rd instar larvae of O.furnacalis was determined by feeding method.The strain ACB3014 was Serratia marcescens.The cumulative corrected mortality of ACB3014 on the 3rd instar larvae increased with the increase of bacterial suspension concentration.On the 7th day after feeding ACB3014 bacterial suspension,the cumulative adjusted mortality of the 3rd instar larvae ranged between 27.78%—77.78%at the concentration of 2×10^(4)—2×10^(8)cfu/mL.On the 13th day of inoculation,when the concentration reached 2×10^(8)cfu/mL,LC_(50)and LT_(50)against the 3rd instar larvae of O.furnacalis were 3.79×10^(3)cfu/mL and 3.93 days,respectively.In addition,the infected O.furnacalis larvae are dark red and black and are pyoid and festering,giving off a strong odor.In conclusion,ACB3014 strain has good insecticidal activity against O.furnacalis larvae and has a high potential as a green biological control resource for O.furnacalis.