| Spodoptera litura Fabricius is one of the most important pests of vegetables, plants and many crops. It is abound in the world recently and their damage are serious. Because of the large-scale use and irrationality application of chemical pesticides, the level of drug resistance of Spodoptera litura Fabricius increase obviously. It also gave great difficulties to pest control. Abusing chemical causes the environmental pollution, ecosystem destruction; it also hurt the health of human and animals. So effort to reduce the use of chemical pesticides to promote biological control in the integrated pest management is the need for sustainable agricultural development.Spodoptera litura multicapsid nucleopolyhedrovirus (SpltMNPV) is a biological pathogen, it can control the host population obviously and has already been commercial production. However, because the virus has high host specificity and do no effect to other insects except target organism. However, it can't effect on pests control as quickly as possible. It has some shortages in practical application. For expanding the control species of the insects and improving the insecticidal effect, we use SpltMNPV and mix emamectin benzoate with them, then test the toxicity of the mixtures in the lab and in the field. At last, some obvious results are gotten. As the same time clone and sequence analysis of pif-2 gene that has some contact with per os infection of SpltMNPV is done at the level of molecule. Main results are as follows:1. In the laboratory in conditions of different mixtures, concentrations and temperatures, we mixed Chinese SpltMNPV(CN), three strains of Japanese SpltMNPV(A,B,C) with emamectin benzoate and then tested their toxicity to the larvae of Spodoptera litura. The result was that the mix of 106PIB/mL SpltMNPV Japanese strain (B) and 1% emamectin benzoate's 1000 times dilution has strong and obvious biological activity. Its LT50 was 22.22% and 44.44% shorter than the single emamectin benzoate and nucleopolyhedrov- iruse separately. It had an obvious effect.2. Chose the compound biological insecticides to do experiments for controlling Spodoptera litura Fabricius, Plutelaxylo stelo, Diaphania iadiea in the field. The results showed that the compound biological insecticide had 76.67%~88.48% and 92.92%~ 96.30% revised mortality for Spodoptera litura Fabricius after using 4days and 7days, and a little higher than 71.63%~84.16% and 87.56%~92.77% of single emamectin benzoate and more higher than 21.95%~45.13% and 68.83%~86.11% of single virus. As the same time, the compound insecticide also can control Lepidoptera pests such as Plutelaxylo stelo and Diaphania iadiea and so on. It has greater applied value on production.3. Clone and analyzing nucleotide and amino acid sequence of gene pif-2 in SpltMNPV Japanese strain(B)was done at the molecular biological level. The second-structure of protein PIF-2 was predicted and homology between a series of pif-2 at the level of molecular system was analysed. It had contributed to the improvement and development of this virus insecticide, and further study of baculovirus.
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