| Helicoverpa armigera nuclear polyhedrosis virus is a very effective bio-pesticides, but it has some disadvantages also, such as slow insecticidal effect, insecticidal narrow range. For this case, we tried to use exogenous neurotoxin genes to recombinant viruses, in order to enhance the control effect of baculoviruses.The spider toxin gene Ar1 b, scorpion toxin gene Metx3 and RjAa17 f gene were expressed in Sf9 cells. The LD50 and the midgut membrane potential of health H. armigera made by Ar1 b, Metx3 and RjAa17 f toxic proteins were determined. And bioassays of the Metx3-HearNPV and Rj Aa17f-HearNPV that were constructed already were determined also.LD50 of RjAa17 f, Ar1 b and Metx3 were 108.12 μg/g, 199.44 μg/g and 231.02 μg/g, respectively. It showed that RjAa17 f toxic protein had the highest toxicity, Ar1 b toxic protein followed and Metx3 had the weakest. The midgut membrane potential in 3~12 h after acting on H. armigera midgut treated with the three different toxin proteins showed a gradual increasing trend, but over time, the amplitude of increase were decreases finally. The effects of three toxic proteins on the membrane potential were that RjAa17 f had the strongest, followed Ar1 b, and Metx3 had the weakest.The LT50 and LT90 by RjAa17f-HearNPV were found a faster killing speed. The LT50 was shortened 23.4% than wt-HearNPV while LT90 was shortened 23.3% than wt-HearNPV. The LT50 and LT90 by Metx3-HearNPV were found a faster killing speed also. The LT50 was shortened 19.8% than wt-HearNPV while LT90 was shortened 17.5% than wt-HearNPV.In conclusion, the results had a very significant impact after acting on H. armigera no matter the three different toxic proteins expressed in vitro, or recombinant viruses inserted exogenous genes.The effects of membrane potential after acting on H. armigera had a positive correlation with the virulence of three different toxic proteins and had some relevance with the formation of virulence because Ar1 b, RjAa17 f were both higher than Metx3. |
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