Solid Fermentation And Preparation Research In Isaria Fumosoorosea Of High Pathogenicity On Diaphorina Citri (Kuwayama)

The Asian citrus psyllid(ACP),Diaphorina citri(Kuwayama)as an important invasive pest of citrus,it can transmit the bacterium that causes huanglongbing(HLB;citrus greening disease),which makes damage to citrus.Recently,biological control has become research hotspot owing to the increase of psyllid's insecticide resistance and food safety problem.Isaria fumosorosea has great potential for biological control of D.citri,thus,it will be of great significance to control D.citri by screening I.fumosorosea isolates of high pathogenicity,and researching on highly pathogenic biological agents.In this article,we have screened isolates of L fumosorosea integrated with better conditions,optimized liquid and solid fermentation medium and culture conditions,collected conidia and preliminary research I.fumosorosea suspoemulsion formulation for D.citri biological control.The results are following:1.Firstly,I.fumosorosea isolates(F-HY002-1A,F-HY002-4F,F-HY002-6D,F-HY002-7A,and F?HY002-ACPHali)conserved in our lab were rejuvenated.We also evaluated their virulence to D.citri adults with the concentration of 1.0 × 10 conidia/mL,the mortality of adults was between 67%and 78%,and every difference was not significant(t=0.525,P>0.05).Five isolates were screened for their yield and colony growth rate,results showed that,the yield(2.30 ± 0.46 conidia/mL)and colony growth rate(3.13 mm/d)of isolate F.HY002-ACPHali were higher than others.So the isolate F-HY002-ACPHali was selected for D.citri biological control.2.Choosing F-HY002-ACPHali as the tested isolate,we screened the liquid medium and fermentation conditions by single factor experiment and orthogonal design.The results showed that:25 g/L glucose,25 g/L yeast powder,CuSO4 and ZnSO4 100 mgl L,inoculation amount of conidial suspension 6%(v/v),initial pH 6,loaded liquid medium 60mL(250ml Erlenmeyer flask),at 26? in a rotary shaking incubator operated at 125r per minute after 72 hours resulted in the maximal biomass 19.0g/L.Mycelium produced will be used for solid fermentation.3.Among wheat bran,com flour,soybean meal,peanut meal,broken rice and rice braD,com flour ean produce largest spore yield.The solid fermentation media and culture conditions of F?HY002-ACPHali were optimized by the orthogonal experiment:corn flour as marn solid medium,initial pH 5,initial moistUre content 70%(v/m),and inoculated with liquid medium 10%(v/m).The spore yield reached 5.92xlogconidia per gram com flour by cultivating 15 days at 25 C.We also expanded the fermentation according to the optimum fermentation conditions,the spore yield reached 8.39g per 500g com flour and 1.61 × 1011 conidia per gram spore powder,the eonidial viability was 92.34%.4.Screening the main additives of conidial suspoemulsion formulation,the production process of suspoemulsion formulation as follows:Tween-80 0.5%(v/v)as emulsifier,CN-Na 0.3%(v/v)as suspension stabilizer,VC 0.3%(v/v)as UV protecting agent,each additive was added to the mineral oil,stir well,then add 10%(v/m)spore powder.Suspoemulsion formulation is stored stability:spore germination rate is higher than 80%when stored at 4 C and 25 0C for 90 days.The suspoemulsion formulation showed high pathogenicity against D.citri adults,and the LC50 of suspoemulsion formulation to adults is 1.60×105 conidia/mL,less than LC50(8.80 × 106 conidia/mL)of spore suspension.