Development Of Resistance To Fungal Pesticide Polyoxin

Although chemical pesticides to control pests has many advantages,but after a lot of use of chemical pesticides trigger a series of security problems,so you can control methods to overcome theseproblems,Biocontrol got more attention from researchers.There are many methods of biological control,but not every one is suitable for pest control,insect pathogenic fungi insecticides has many advantages,for example,take the initiative and have a lethal effect on infected host;other microbial infection cycle pesticides does not have a feature;generally does not produce host resistance;therefore focused on both domestic and foreign insect pathogenic fungi insecticides.Nomuraea rileyi(Nomuraea rileyi, referred to as Nr,also known as the Leidenfrost moth mildew),all over the world are distributed,as important fungal pathogens of insects.The bacterial insecticidal virulence and host range,can live more than 30 kinds of Lepidoptera pests,especially for lepidoptera Noctuidae insects have strong pathogenicity,can cause an epidemic disease in many agricultural systems, and targeted to human body and other non target insects including parasites and predators without toxic effect.Polyoxin is a broad-spectrum antibiotic fungicide,this kind of fungicide because of its inner suction conduction property and water solubility characteristics,good effect of resistance of crops,the impact on the environment is very small,is widely used.At present the sensitivity was not the domestic and foreign related Nomuraea rileyi of agricultural antibiotic bactericide has the system reports, and the use of antibiotic resistance of Nomuraea rileyi for biocontrol is seldom reported.So the research of agricultural antibiotic susceptibility to biocontrol Nomuraea rileyi,and use of various induction methods produce resistance Nomuraea rileyi,for biological control and chemical control combined with important significance.This research through the virulence of 10 strains of Nomuraea rileyi strain screened indoor determination,has high toxicity against Spodoptera litura strains, and to high virulent strains by UV mutation and mold containing polyclonal antibody induced by flat,isolated from the polyoxin of Nomuraea rileyi strain.To provide a basis for Nomuraea rileyi and polyoxin preparation research.The main results are as follows: 1.This study through the use of 10 strains of Nomuraea rileyi strain of 3 instar larvae of Spodoptera litura induced by virus forces were measured, Nomuraea rileyi after infection of the muscardine cadaver first white, then into a dark green.The early larvae died of the infection,stiff, straight or twisted,the onset of anaphase larvae emerge spit water, diarrhea and other symptoms.The results show that different strains of pathogenic differences,a comprehensive comparison of the muscardine cadaver rate and corrected mortality rate and median lethal time(LT50), of which Nr19 strains virulent,corrected mortality and the muscardine cadaver rate were 100% and 86.6%,median lethal time LT50 for 5.0501 d, Nr16 and Nr41 followed,corrected mortality respectively 100% and 93.2%, the muscardine cadaver rate were 80% and 85.7%,median lethal time LT50 respectively for 3.9436 d and 4.2130 d.With Nr16,Nr19,Nr41 used for subsequent test. 2.To the screening of the Nr16, Nr19, Nr41 strain as the research object, based on the strain suitable for the lethal rate of 75-85%.Determination of UV mutagenesis condition:in the spore concentration was 1x107/m L, using 30 W UV lamp,irradiation distance is 3cm.Nr16,Nr19,Nr41,irradiation time respectively is 2.5min, 4min, 3.5min.Growth inhibition sensitivity of Nomuraea rileyi element of mildew were determined by the method of multi rate of mycelium.We found that different Nomuraea rileyi strain on polyoxin sensitivity exist certain differences.In 3 strains with high virulence strains,strain Nr4101 EC50 Nr1601 maximum,minimum EC50 value,respectively1.0540mg/m L and 0.4377mg/m L. 3.On the basis of polyoxin in use concentration field is 1.67-2.50g/m L. Combined with small inhibitory concentration of 3 strains of.In containing polyoxin plate,by applying direct spore screening by Nomuraea rileyi anti polyoxin strains.To obtain a drug-resistance Nomuraea rileyi strain Nr16-I.Verification results show that the growth of the strain Nr1601 in containing polyoxin and not containing polyoxin plate.Nomuraea rileyi Nr16-I colony color in this experiment,the screening of the milky white,colony morphology to villous,spore powder is light green,in the SMAY medium is generally about 3-5 days began to sporulation.