Characteristics Of Physiology And Biochemistry Research And Application Research Of A Pathogenic Strain Of No-Sporeforming To Parocneria Orientia

A pathogen was isolated from the larva of Parocneha orientia whose body was atrophic and rubescent. Its pathogenicity was testified by law of KOCH. This thesis has been studied on strain identifications toxicity of this pathogen on 2-instar larva of Parocneria orienta in lab and field,toxicity of this pathogen on 2-instar larva of silkworm in lab. The main results are as follows:1. The 16S rDNA extend sequence of pathogen has a hundred percent on homology with the conservative sequence of Brevundimonas bullata by way of physiological and biochemical test,homology analysis and phylogenetic analysis. So it was identified as Brevimdimonas bullata.2. Toxicity of pathogen on 2-instar larva of Parocneria orientia in lab was assayed by means of oral infection. The results showed that the linear regression relationship between the logarithm(y) of concentration and the probability(x) of corrected mortality is Y=-9.7851+6.667X, and the median lethal concentration is LC₅₀=9.28×10⁸ cfu/mL. the results also showed that this pathogen had obvious function of restrain infect larva take food. And the larva which can not killed all obvious under the antitheses in accumulative dejecta weigh,length of body,avoirdupois,the ratio of eclosion,amount of nit and the ratio of hatch.3. Toxicity of Brevundimonas bullata+ PoNPV ( LC₅₀ ) and Brevimdimonas bullata+1mg/L Mieyouniao on 2-instar larva of Parocneria orientia in lab was assayed by means of oral infection. The results showed that the linear regression relationship between the logarithm(y) of concentration and the probability(x) of corrected mortality are Y=29.2255+6.205X and Y=27.6977+5.491X; and the median lethal concentration are LC₅₀=2.23×10³ cfu/mL and LC₅₀=1.15×10⁴cfu/mL; and the ratio of synergistic effect of Mieyouniao is S_r=162609. and adding PoNPV (LC₅₀) to Brevundimonas bullata, the mixtue has distinct synergistic effect and superposition effect. Spraying control on 2-3 instar larva of second generation of Parocneria orientia with Brevundimonas bullata,Brevundimonas bullata+ PoNPV(LC5o)and Brevimdimonas bullata+1mg/L Mieyouniao in field, the results showed that synergistic effect is distinct, and death rates of larva because of synergists are more than those no synergists.4. Toxicity of Brevundimonas bullata,Brevundimonas bullata+ PoNPV (LC50) and Brevundimonas bullata+1mg/L Mieyouniao on 2-instar larva of silkworm in lab was assayed by means of oral infection. The results showed that 3 kinds of treatments all have no toxicity on 2-instar larva of silkworm the results also showed that the larva which is treatmented all have no difference with the antitheses in length of body,avoirdupois,the ratio of eclosion,amount of nit and accumulative dejecta weight.