杨小舟蛾新病毒的鉴定及其生物活性研究

Identification and Biological Activity of a New Virus of Micromelalopha sieversi(Staudinger)(Lepidoptera:Notodontidae)

[目的]杆状病毒在农林害虫的生物防治中起着重要的作用,本研究鉴定1株具有高毒力的杨小舟蛾新病毒,为害虫的生物防治提供新病毒资源。[方法]通过研究该病毒的超微结构和生物活性确定其生防潜力。[结果]超微结构表明,该病毒包涵体多呈椭圆形,平均大小为0.43×0.21μm;包涵体中包埋一个杆状病毒粒子,具有颗粒体病毒结构特征,命名为杨小舟蛾颗粒体病毒(MisiGV)。生物活性显示,MisiGV对杨小舟蛾幼虫有致死作用,对3龄幼虫的半致死浓度LC_(50)为2.37×10^(5)OBs·mL^(−1);当浓度为1.2×10^(7)、4.0×10^(6)、4.0×10^(5)、1.2×10^(5)和4.0×10^(4)OBs·mL^(−1),对3龄幼虫的半致死时间LT_(50)随着病毒浓度的降低而增大,分别为7.55、11.61、14.69、16.06和17.62 d。不同龄期幼虫对MisiGV的敏感性表明,虫龄较小越容易受到病毒的侵染,而且幼虫的死亡速度依赖于虫龄和病毒浓度。当浓度为4.0×10^(6)OBs·mL^(−1)时,2和4龄幼虫的最高累计死亡率分别为90.00%和57.78%,而在该浓度下,杀死50%的2龄幼虫的所需时间≈6.81 d,4龄≈12.89 d;当病毒浓度为4.0×10^(4)OBs·mL^(−1)时,2和4龄幼虫的最高累计死亡率分别为83.33%和36.67%,LT_(50)值分别为11.91 d和25.65 d。此外,MisiGV对存活幼虫化蛹率和羽化率也有一定影响,病毒液浓度越高,化蛹率和羽化率越低。当MisiGV浓度为4.0×10^(4)OBs·mL^(−1),MisiGV对羽化率的影响不明显。[结论]本文报道的MisiGV新病毒是具有开发潜力和应用前景的生防因子。

[Objective]To identify a new viral strain of baculovirus which have high virulence against Micromelalopha sieversi(Staudinger).[Method]The ultrastructure and biological activity of this virus were study to determine its biological control potential.[Result]The ultrastructure showed that the occlusion bodies of the virus mainly consisted of ellipse,with an average size of 0.43×0.21μm and the inclusion bodies embedded a single rod-shaped virion.It had the structural features of a granulovirus named as Micromelalopha sieversi granulovirus(MisiGV).Biologic activity assays showed that MisiGV is highly virulent in the 3rd instar larvae of M.troglodyta,with an LC_(50) of 2.37×10^(5) OBs·mL^(−1).The LT_(50) of the virus increased with the decreasing of virus concentration.When the virus concentration were 1.2×10^(7),4.0×10^(6),4.0×10^(5),1.2×10^(5) and 4.0×10^(4) OBs·mL^(−1),the LT_(50) values were 7.55,11.61,14.69,16.06 and 17.62 days,respectively.The susceptibility of larvae at different instar to different MisiGV concentrations indicated that the younger larvae of M.troglodyta were more susceptible to virus than the older larvae,and the speed of larval death depended on the age and virus concentration.Generally,at 4.0×10^(6) OBs·mL^(−1),the highest cumulative mortality of 2nd and 4th instar larvae were 90.00%and 50.58%,respectively,whereas the times required to kill 50%of the 2nd and 4th instars were approximately 6.81 days and 12.89 days.At 4.0×10^(4) OBs·mL^(−1),the highest cumulative mortality of 2nd and 4th instar larvae were 83.33%and 36.67%,the LT50 values were approximately 11.91 days and 25.65 days.In addition,after different concentration of MisiGV inoculation,the pupation and emergence rate of surviving larvae were significantly lower than that of the control.However,no significant difference on the emergence rate was observed at 4.0×10^(4) OBs·mL^(−1) MisiGV concentration.[Conclusion]A new virus-MisiGV is reported.This virus-MisiGV is a biological control factor with development potential and application prospects.