Screening Of Lecanicillium Lecanii Isolates With High Resistance And Virulence Against Phenacoccus Solenopsis

This study was taken to suppress a target pest, Phenacoccus solenopsis, to find ways to improve the virulence of wild strain fungi Lecanicillium lecanii to shorten the killing time of targeted pests. We also studied the relationship between the fungus’s UV tolerant and Superoxide Dismutase acitivity in order to provide some scientific references for reforming of anti-ultraviolet.Our results showed that by the radiation of the sunlight, the conidia germinations, the 23 isolates of Lecanicillium lecanii reduced. V14, V3387, V10, V3450 and V4060 had better UV-tolerant than other isolates. The UV-tolerant had certain correlation with SOD activity, with 0.439 correlation coefficient.In testing all seven pesticides, results showed that bactericides inhibited the fungus to a higher degree than insecticides. Azadirachtin had the best compatibility with the 4 isolates of Lecanicillium lecanii and V3450 had the best pesticides tolerant.In the screening test, results showed that V3450, V17, V4060 and V20 from 23 isolates can significantly infect the pests. V20 had the highest virulence both to 3rd-instar nymph and female adults for the corrected accumulative mortalities on the 9th day reached 81.67% and 66.67% at higher concentrations (1.6×107 conidia/mL). Mixture of V3450 and Azadiractin raised the speed and mortality rate to the pest for the synergism to 3rd-instar nymph reached the maximum of 10.25% on the 5th day and the synergism to female adults reached the maximum of 22.87% on the 4th day.