The Synergistic Effect And Application Of Bacillus Thuringiensis And EoNPV On The Control Of Ectropis Oblique Prout

Ectropis obliqua Prout is one of the most important pests which damage the tea-trees in the district of Zhejiang, Jiangsu and Anhui province in China. Bacillus thuringiensis (Bt) and virus are two main bio-pesticides used to control Ectropis obliqua currently. There are some disadvantages of control in practical applications, such as less effective, unstable control effect and short effective period, resulting in the damage caused by E. oblique can not be controlled under the allowable standard. In this study, two new strains with high virulence to E. obliqua have been screened, and the synergistic effect of Bt with EoNPV has also been studied.Different strains of Bt caused larval mortality from 0 to 41.5%, and the LC₅₀ of Bt to E. obliqua was 56.7330uL/mL, 36.4-fold higher than that to Plutella xylostella. Those indicated the pest was not susceptible to Bt. The control effects of EoNPV were mainly influenced by the factors of temperature and light.By collecting virus contained soil, isolation, inoculation and re-isolation, a new Bt strain 02-85 was selected. Its LC₅₀ to E. obliqua was 6.9043uL/mL, the virulence was 2.15 times than that of the strain Yz-2. Two new EoNPV strains named EoNPV-A and EoNPV-B were also screened from virus infected E. obliqua. A total mortality of 100 percent of E. obliqua was obtained after three days when treated with those two isolated viruses at the concentration with 2×10⁴PIB/mL. To replicate the virus, the larvae at second instars was selected to inject EoNPV at concentration of 5×10⁵PIB /mL, and finally total of 6.8×10⁸PIB virus per insect was obtained.There was a combined effect of EoNPV and Bt to control the larvae of Ectropis obliqua. The CTC of 1.0×10⁷ PIB/mL EoNPV+2000IU/uL Bt was 128.03, and the LT₅₀ was about 2 days shorter than using EoNPV only. At the same time, it could control other pests of Lepidoptera and cause feeding resistance action of E. obliqua. The control effect to Iragoides fasciata was up to 85.8%.According to the synergistic effect between Bt and EoNPV, a preparation called Chihoqing has been produced. This product was safe to fish and birds, and did no harm to...