Abstract
To conserve and utilize natural enemies for comprehensive control of insect pests in peach orchards,the seasonal and annual variations of population quantities of the five kinds of insect pests with their natural enemies were systematical investigated in the Yuhualu juicy peach orchard.The findings of a paired t-testing demonstrated that the t values of five kinds of main pest numbers,i.e.Empoasca flavescens,Myzus persicae,Tetranychus viennensis,Cleoporus variabilis and Stephanitis nashi,indicating that no significant differences existed in the numbers of five kinds of insect pests in Yuhualu juicy peach orchard between the two spring-summer seasons of 2010 and 2011.Whilst the t values of the seven kinds of natural enemy numbers,i.e.Erigonidium graminicola,Misumenops tricuspidatus,Theridion octomaculatum,Clubiona japonicola,Propylaea japonica,Chrysopa sinica and Epistrophe balteata,all were significantly lower than 2.16(t0.05 value),revealing that there were also no significant differences in the numbers of the seven kinds of natural enemies between the two spring-summer seasons of 2010 and 2011.Surprisingly,the t value of Harmonia axyridis was 2.39 2.16(t0.05 value),showing that the difference in numbers was significant between the two spring-summer seasons of 2010 and 2011.The further analysis indicated that the t values of Empoasca flavescens,Stephanitis nashi,Misumenops tricuspidatus,Harmonia axyridis,were,respectively,5.63,76.38,3.28 and 4.82 3.01(t0.01),indicating that there were significant differences in their numbers in Yuhualu juicy peach orchard between the spring-summer season and the autumn season of 2010,whereas no significant differences existed in the others.Moreover,the quantity,time and space framework of Myzus persicae,Empoasca flavescens,Tetranychus viennens,Cleoporus variabilis,Stephanitis nash and their predatory natural enemies in 2010 spring-summer season and autumn season,as well as 2011 spring-summer season were systematically studied using grey system analysis,ecological niche analysis and aggregated-intensity index analysis of spatial patterns.The synthetic ranking results indicated that,in 2010 spring-summer season,the orders of main natural enemies of Empoasca flavescens were Misumenops tricuspidatus,Chrysopa Sinica and Theridion octomaculatum,whereas the ranks of main natural enemies of Tetranychus viennensis were Clubiona japonicola,Theridion octomaculatum and Erigonidium graminicola.In 2011 spring-summer season,the orders of main natural enemies of Myzus persicae,Empoasca flavescens,Cleoporus variabilis,Stephanitis nashi and Tetranychus viennensis,were,respectively,Epistrophe balteata,Harmonia axyridis and Misumenops tricuspidatus;Erigonidium graminicola,Propylaea japonica and Misumenops tricuspidatus;Erigonidium graminicola,Misumenops tricuspidatus and Theridion octomaculatum;Misumenops tricuspidatus,Propylaea japonica and Erigonidium graminicola;Clubiona japonicola,Theridion octomaculatum and Erigonidium graminicola.In 2010 autumn-winter season,the ranks of main natural enemies of the Empoasca flavescens and Stephanitis nashi,were,respectively,Chrysopa Sinica,Erigonidium graminicola and Misumenops tricuspidatus;Theridion octomaculatum,Erigonidium graminicola and Misumenops tricuspidatus.The further analyses showed that the average λ values of Empoasca flavescens,Stephanitis nashi and Tetranychus viennensis in 2010,and Myzus persicae,Cleoporus variabilis,Stephanitis nashi and Tetranychus viennensis in the spring-summer season of 2011 all are more than 2,and in the four different directions of peach tree crown,the λ value of Tetranychus viennensis in the 2010 spring-summer season,and Empoasca flavescens in the 2010 autumn-winter season,as well as Cleoporus variabilis in the 2011 spring-summer season all are also more than 2,suggesting that the gathering cause of the insect pests resulted from themselves.However,the λ values of the other insect pests and natural enemies all were less than 2,indicating that their gathering was caused by certain environment factors.
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