青海草原毛虫蛹期两种寄生天敌昆虫寄生率调查以及与寄主相互作用关系分析

Investigation of parasitism rate of two parasitic natural enemies of Gynaephora qinghaiensis in pupal stage and analysis of their interaction with hosts

【目的】在长期的进化过程中,天敌昆虫与寄主之间形成相互依存,相互制约的关系,正是自然界这种对立统一的关系维持着天敌昆虫与寄主种群的相对稳定。因此,生物防控不仅需要掌握害虫的发生规律和种群动态,而且还需研究天敌的种群动态以及害虫与天敌之间的相关关系。【方法】在青海省玉树州共设6个调查样地,对青海草原毛虫Gynaephora qinghaiensis种群密度以及草原毛虫蛹期两种寄生天敌昆虫(三江源草原毛虫金小蜂Pteromalus sanjiangyuanicus和草毒蛾鬃堤寄蝇Chaetogena gynaephorae的自然寄生率进行为期5年的同步调查(2015-2019年),并对它们的自然寄生率与草原毛虫的种群密度之间的相关关系进行分析。【结果】青海草原毛虫的种群密度在1.0-78.4头/m^(2),三江源草原毛虫金小蜂自然寄生率在9.2%-25.0%,草毒蛾鬃堤寄蝇自然寄生率在0.7%-4.4%;三江源草原毛虫金小蜂对草原毛虫蛹具有偏雄性寄生特征;连续3年三江源草原毛虫金小蜂寄生率与下一年的青海草原毛虫种群密度之间具有显著的负相关关系(P<0.05)。【结论】研究表明,三江源草原毛虫金小蜂对青海草原毛虫种群增长具有明显的抑制效应,适宜作为青海草原毛虫生物防控中的优势寄生天敌。研究青海草原毛虫寄生天敌昆虫与青海草原毛虫种群消长关系,为草原毛虫生物防控中寄生天敌昆虫的选择及其扩繁提供科学依据。

[Aim]Through a long evolutionary process,a kind of interdependent and restrictive relationship has formed between insects and hosts.It is this unity of opposites in nature that maintains the relative stability of insect and host populations.Therefore,biological control requires information not only on the occurrence law and population dynamics of pests but also on the population dynamics of natural enemies and the correlation between pests and natural enemies.[Methods]In this study,6 sites were used to investigate the population density of Gynaephora qinghaiensis and the natural parasitism rates of two natural enemies(Pteromalus sanjiangyuanicus and Chaetogena gynaephorae)of G.qinghaiensis pupae for 5 years(from 2015 to 2019)in Yushu Prefecture,Qinghai Province.Meanwhile,the correlations between the natural parasitism rates of the two natural enemies and the population density of G.qinghaiensis were analyzed.[Results]The population density of G.qinghaiensis ranged from 1.0 to 78.4 ind./m^(2),the natural parasitism rate of P.sanjiangyuanicus was 9.2%-25.0%,and the natural parasitism rate of C.gynaephorae was 0.7%-4.4%.Moreover,the parasitism of G.qinghaiensis by P.sanjiangyuanicus was male biased.There was a significant negative correlation between the parasitism rate of P.sanjiangyuanicus and the population density of G.qinghaiensis in the next year(P<0.05).[Conclusion]The results revealed that P.sanjiangyuanicus had a significant inhibitory effect on the population growth of G.qinghaiensis and was suitable as the dominant natural enemy for the biological control of G.qinghaiensis.Studying the relationship between the parasitic natural enemies and population growth of G.qinghaiensis provides a scientific basis for the selection and propagation of parasitic natural enemies of this species in relation to biological control.