Synergism Of The Strain HBF-1 Of Bacillus Thuringiensis To The Strain HD-1 Against Helicoverpa Armigera (Lepidoptea Noctuidae) And Plutella Xylostella (Lepidoptera Plutellidae)

This research screened the strain HBF-1 that has synergic action on the strain HD-1 against Lepidoptera pests. The strain HBF-1 belongs to the Bacillus thuringiensis serovar japonensis, and the serum type is H23. It has high toxicity to larvae of Anomala exoleta and A. Corpulenta. But it has no toxicity to pests of Lepidoptera. The result indicated that the strain HBF-1 had high synergic action on the strain HD-1, its CTC is 236.The research of the synergism of the strain HBF-1 explicated that the live spores from the strain HBF-1 and the fermented supematant had the synergistic function on the strain HD-1. Synergism of constituents from the strain HBF-1 culture was evaluated by using a bioassay system (artificial diet) against larvae of Helicoverpa armigera and Plutella xylostella. Provided the different categories of insects, the concentrations of spores from strain HBF-1 that had the biggest synergistic function to the strain HD-1 were also different.The research on the synergic mechanism of the strain HBF-1 indicated that it had not toxicity to pests of Lepidoptera and could not germinate in the gut of the insects. But it could affect Heliothis armigera larvals normal growth directly, could make the weight increment before, and then the development dilatoriness, the period delay. The adult produce the amount of egg obvious reduced, the next generation egg could not hatch from eggs normally. Passing the optical microscope observation, I detected that feeding the infection feedstuff with the live spores from strain HBF-1 on the Heliothis armigera larval, when the larval grew to 2nd stadium; the bowel wall cell had no obvious variety with normal the cell. But when the larval was 3rd stadium, the microvillus of the bowel wall cell of the midgut were obviously less than the normal cell, the microvillus of part have had already shed off; The reborn cell compared the normal reborn cell to increase; The pillar cell coping inflated, the microvillus arranged untidy, and the microvillus of some parts shed off; The bowel wall compared the normal to increase thick. When the larval grew to 4th stadium, destruction is more and seriously.The determination result of the enzymatic activity indicated that after four days feeding the Heliothis armigera larval on the live spores 100.00 μg/g from strain HBF-1,...