Study On The Prevention And Control Of The Agrotis Ypsilon Using To Insect Pathogenic Nematodes In Vega

Agrotis ypsilon is one of the most important tobacco underground pest,the harm of tobacco,the larvae rate of seedling shortage,seriously affected the yield and quality,and even failure.The abuse of chemical pesticides leads to environmental pollution,pesticide residues,insect resistance and other problems.As a result,biological control of Agrotis ypsilon is essential.In order to select the broad-spectrum insecticidal effect and insect pathogenic nematode strains have the potential market,this study used bioassay method in laboratory,the determination of Steinernema spp.?Steinernema carpocapsae?and heterorhabditids?Heterorhabditis bacteriophora?,a total of 5 strains of black cutworm larvae of different ages the pathogenicity,selected one of the most powerful of the Agrotis ypsilon pathogenicity of nematode strains in order to study the strains of tobacco control,Agrotis ypsilon at the same time,to explore the application effect of nematode strains in the field.The results are as follows:1 in laboratory by bioassay method,the determination of Steinernema spp.?Steinerne-ma carpocapsae?and heterorhabditids?Heterorhabditis bacteriophora?,a total of 5 strains of black cutworm larvae of different ages pathogenic ity.The results show that the entompa-thogenic nematode infection ability of cutworm larvae with S.carpocapsae-A11,S.carpoc-apase-1,S.longicaudum X-7,H.bacteriphora-1,H.bcateriphora-2,the 3 instar larvae correc-tion percentage mortality were 43.25%,31.85%,17.65%,18.55%,34.11%,of black cutwo-rm larvae.The force is as follows:S.c-A11>Hb-2>S.c-1>Hb-1>X-7>CK.The pathogenic-ity of the same strains of entomopathogenic nematodes cutworm in different instar from large to small in turn is at the age of 3>4>5,the maximum infectivity of the 3 instar larvae of S.carpoocapsae-A11 shows that the pathogenicity of entomopathogenic nematode strai-ns of Agrotis ypsilon Rottemberg in tobacco field with 3 instar larvae was the strongest.2 Determination of dominant nematode strains S.carpocapsae-A11 at 18?and 25?and30?temperature under the condition of sports ability,the results show that the motor ability of different temperature on nematodes significantly,treatment with 12h at 18?,25?and 30?temperature,the amount of exercise was 2.90%,7.97%nematodes and 8.84%respectively;the amount of movement of the nematode 24h after treatment were 8.55%,23.04%and 19.28%respectively.The infectivity of dominant nematode strains S.carpocap-sae-A11 with different concentrations on cutworm were determined.The results show that in the 6 concentrations tested?160IJs/mL,320IJs/mL,the 640IJs/mL,1280IJs/mL,2560IJs/mL,3500IJs/mL?,with the increase of concentration,Agrotis ypsilon mortality increased obviously when the concentration was 2560,the Agrotis ypsilon mortality trend has slowed down,the overall presentation of"S"shape.One of the highest mortality rate of treatment was 3500IJs/mL,the mortality rate was 85.40%,followed by 2560IJs/mL,the morta lity rate was 83.33%,followed by 1280IJs/mL treatment,the mortality rate was 66.67%,640IJs/mL mortality rate was 39.33%,320IJs/mL mortality rate was 23.33%,the lowest is 160IJs/mL and CK,was 6.7%,between the two results is almost no difference,therefore the control effect of low concentration of nematode cutworm is not obvious.3 Study on the interaction of commonly used biological agents of Beauveria bassiana and Metarhizium anisopliae and Bacillus thuringiensis and dominant nematode strains S.carpocapsae-A11 indicates that the 3 kinds of biological agents tested?Metarhizium anisop-liae,Beauveria bassiana,Bacillus thuringiensis?on S.carpocapsae-A11 nematode survival rate had no effect.S.carpocapsae-A11 nematodes respectively with 4 concentration?1×10⁷,1×10⁶,1×10⁵,1×10⁴spore/mL?combined with biological agents,with the increase of the concentration,the better control effect of black cutworm.S.carpocapsae-A11 nematodes were used in combination with the same concentration of biological agents,and the lethality rates of three biological agents against Agrotis ypsilon were Bacillus thuringiensis,Beauveria bassiana,and Metarhizium anisopliae.The optimum combination of interaction effects was S.carpocapsae-A11,with a concentration of 1×0⁷ spores/mL,and Bacillus thu-ringiensis in combination.4 By pot experiment and field test,evaluation of the dominant nematode strains S.car-pocapsae-A11 in the application field,results in indoor pot tests in five treatments:1?S.c-A11+BTD variants,water irrigation,fertilization 2 times?,II?S.c-A11+BTD variants,applied2 times?and III?S.c-A11+BTD variants,scattering and root irrigation combined with application,2?,IV?single application of S.c-A11,water irrigation,fertilization treatment?2times?and V single application of BTD variant formulations,powder preparation applicator,applied 2 times?;the victim seedling rate were 35.05%,22.50%,18.05%45.50%and 50%.The treatment with the best seedling survival rate was 58.68%,the effect of the minimum treatment V seedlings,seedling rate was 18.63%.Field test results show that the four treatments:A(single application of nematode S.c-A11 preparations,nematode dose of80IJs/cm² application head 2 times,root irrigation);B?nematode S.c-A11 variants with BTD mixed powder agent were broadcast 2 times?;C?S.c-A11 and BTD variants with mixed nematode and for root irrigation applied 2 times?;D?nematode S.c-A11 variants with BTD mix,first after transplanting,the root irrigation was carried out with water,second times in the cultivated soil;the effect of powder preparation applicator?seedlings were 50%,50%,65.63%,78.75%,seedling D was the best treatment for 78.75%;the overall effect is:D>C>B>A>CK.Therefore,in the actual production,the use of S.carpocapsae-A11 and BTD elegans variants?1×10⁷spores/mL?mix,first after transplanting,the root irrigation was carried out with water,second times in the cultivated soil powder preparation applicator,had the best control effect on tobacco Agrotis ypsilon.