苏云金芽孢杆菌的筛选及其对冷杉梢斑螟的致病力OA

To investigate the pathogenicity of Bacillus thuringiensis(Bt)against larvae of Dioryctria abietella,soil samples were collected from a Pinus sylvestris var.mongolica plantation where D.abietella outbreaks occurred.Bt strains were isolated using the temperature screening method,followed by morphological identification via staining with 0.5%alkaline fuchsin solution.The types of vip3A and cry genes harbored by the strains were identified and analyzed using a PCR-RFLP identi-fication system and specific primer amplification for vip3A.Finally,five Bt strains were confirmed by 16SrRNA gene se-quencing and phylogenetic tree construction,and their pathogenicity to D.abietella larvae was determined.The results showed that five Bt strains were isolated from the soil.Among them,strain BtM0003 contained cry1Aa and cry9Ea,strains BtM0019,BtM0014 and BtM0015 all contained cry1Aa,cry2Ab,cry9Ea and vip3Aa,and strain BtM0004 contained cry2Ab,cry9Ea and vip3Aa.The cumulative corrected mortality of D.abietella larvae treated with the five strains ranked in descending order as follows:BtM0015＞BtM0014＞BtM0019＞BtM0004＞BtM0003.Among them,BtM0015 exhibited the highest cumulative corrected mortality of(88.33±7.64)%,with a median lethal time(LT50)of 3.866 days.