Combined Control Of The Dioryctria Abietella By The Pyemotes Zhonghuajia And The Bacillus Thuringiensis Aizawai

Dioryctria abietella,belonging to the lepidoptera family,mainly eats Pinus koraiensis cones.In recent years,D.abietella become an important forest pest,which has brought great losses to forestry production.By biting the host,Pyemotes zhonghuajia can produce neurotoxins to paralyze and poison the host.After being eaten by insects,Bt spores germinate and reproduce in the intestines of insects,and finally enter the blood through the intestines,eventually leading to the death of insects due to starvation,dehydration and sepsis.In this study,D.abietella was used as the research object.Bacillus thuringiensis aizawai Bonnefoi et de Barjac was used with Pyemotes zhonghuajia(Bta)to study the mortality rate,protective and detoxifying enzymes activity of D.abietella larvae,and the feasibility of the P.zhonghuajia entering the cone cavity.The main research results are as follows:1.Changes occured in mortality and protective detoxification enzymes activity of those D.abietella larvae after feeding on the feed uniformly dipped in the suspension of Bacillus thuringiensis(5 concentrations)for 24 hours.Changes occured in mortality and protective detoxification enzymes activity of those D.abietella larvae treated by Bta.The results showed that Bta could activate the detoxifying enzymes ACh E and GSTs in the those treated larvae.Inhibiting on their Car E activite;CAT and POD showed gradual inhibition with the increase of Bta concentration and the extension of Bta treatment time.The motality rate of larvae treated by 10~9CFU/m L Bta was the highest,and the mortality rate was up to 100%.2.Changes happened in mortality and protective detoxification enzymes activity of different numbers of the P.zhonghuajia(20,30,40,50,60)to D.abietella larvae.The results showed that the larvae treated by P.zhonghuajia could activate ACh E and GSTs in D.abietella.When the larva:mite ratio was 1:20,1:30,1:40 or 1:50,the CAT activation inhibition was inhibited,activated then inhibited,and when the larva:mite ratio was 1:60,the CAT activation inhibition was completely inhibited.Inhibition then activation of Car E and POD was observed at 1:20 or 1:30,and inhibition was observed at 1:40,1:50 or 1:60.The highest mortality rate of larva was found when 60 P.zhonghuajia were infested the body,and the D.abietella mortality was as high as 90%.A simulated outdoor experiment was conducted to explore the feasibility of the P.zhonghuajia entering the cone cavity.The experiment showed that the P.zhonghuajia could crawl into the cone cavity,find and bite the D.abietella along the cavity passage,and eventually cause the larvae to die.3.D.abietella larvae were fed with a diet uniformly dipped in the suspension of Bacillus thuringiensis aizawai(set up 5 concentrations)for 24 h,and then inoculated with 30 P.zhonghuajia to D.abietella larvae.The mortality and protective detoxification enzymes activity changes.The results showed that the combined action of Bta and P.zhonghuajia on the D.abietella were mostly activated the detoxification enzymes ACh E and GSTs,and inhibited the Car E enzymes in the larvae.High concentration(5×10~4,1×10~4CFU/m L)of Bta and P.zhonghuajia combined action showed a trend of activation,inhibition then activation of POD enzyme activity,while medium concentration(5×10~3CFU/m L)showed a trend of activation then inhibition of POD enzyme activity.At low concentration(1×10~3,1×10~2CFU/m L),POD enzyme activity showed a trend of inhibited.The mortality rate of 5×10~4CFU/m L Bta+P.zhonghuajia was the highest,up to 80%.