Native Cydia Pomonella Granulovirus Virulence And Control Effect In Field Determination And Genotype Analysis Of Cydia Pomonella Granulovirus Zhangye Strain (CypoGV-ZY)

This article reported the genotype analysis about a native Cydia pomonella granulouvirus CypoGV-ZY.And on the other hand three native strains CypoGV-KS1,CypoGV-KS2,CypoGV-ZY and one foreign strain CypoGV-BG virulence indoor determination against 3 instar Cydia pomonella larvae.the control effect in field wih the 4 strains carried out at the same time.TO aim at the weaker control effect in field with CypoGV-BG,we studied the virulence change with strong light treatment to the 4 strains.. The main results were summarized as follows:1. Four CypoGV strains virulence determination and pest control effect in field were studied: The LD50 for four CypoGV strains CypoGV-KS, CypoGV-ZY1, CypoGV-ZY2 and CypoGV-BG were 3.43×10~4 OBs/ml, 8.81×10~4 OBs/ml, 1.0~4×10~5 OBs/ml and 5.31×10~5 OBs/ml respectively, in room condition. The results indicated that the highest virulence strain was CypoGV-KS and the other three were similar. But the control effect in field results showed CypoGV-BG was much weaker than three native CypoGVs. The control effect after 3 months showed the average amount of lured codling moth adult per are was 36 /week after treated with CypoGV-ZY for three month, while CypoGV-BG is 63 /week. The fruits damage percentages for CypoGV-ZY and CypoGV-BG controlled orchard were 39.5% and 51.4%, respectively after three month control using each CypoGV.2. Considering the high UV level in Kashgar, Xinjiang is a possible reason of the difference of control effects among different CypoGV strains, a sunlight irradiation assay was carried out to determine the impact of sunlight on virulence of different CypoGV strains exposed in sunlight for 1 hour. The results showed that the rate of virulence decreasing was significantly difference between CypoGV-BG and domestic CypoGV strains. The virulence of treated CypoGV-BG decreased to 51.2% after sunlight assay, but the virulence of three native strains CypoGV-KS1, CypoGV-KS2 and CypoGV-ZY were 86.4%,89.1% and 88.3% under the same assay. The results indicated that different virus strains from different areas developed different resistance to sunlight with strong UV index. 3. The results of genotype analysis of CypoGV-ZY: The PCR results show that the CypoGV-ZY contains the typical genes ORF63-66, which are similar to the reported high virulence genotype A.The results shows that native CypoGVs isolated from drought area in western China developed high resistance to drought and strong UV sunlight. It shed the light on further study and filed application of the native CypoGVs.