Screening And Application Of High-virulence Entomopathogenic Fungi Of Bemisia Tabaci

Bemisia tabaci.(Gennadius)is an important invasive pest of China's flowers,vegetables,tobacco and other economic crops.In recent years,it has caused serious losses to the production of China's economic crops.At present,there are B-Types,Q-types and other biological types,most of the provinces such as Anhui,Sichuan,Jiangsu,etc.are mainly Q-type hazards.At present,the prevention and control of B.tabaci is mainly based on chemical control,which makes B..tabaci resistant.Therefore,we have seriously polluted the environment.Therefore,it is necessary to rationally apply relevant green prevention and control technologies to reduce the use of chemical pesticides.In this study,6 strains of Metarhizium anisopliae and 3 strains of spores were selected from the strain library of Anhui Agricultural University.As a research object,Monillary sinensis was screened for high-virulence fungal strains of B.tabaci,and then a high-efficiency plant-derived pesticide was screened,and the antagonistic test of high-concentration plant-derived pesticides against high-virulence fungi strains was further studied.The fungal strains studied the hatching rate of the larvae and the safety of the adults,in order to determine whether the two could jointly prevent the harm of the white fly.1 Screening of high-virulence entomopathogenic fungi of B.tabaciIn order to screen a strain of high-virulence fungi against B.tabaci,the virulence of 9 different nymphal nymphs was determined by 9 different fungal strains.The obvious difference was that the Bb84 strain of B.bassiana had higher virulence to the nymph,and the cumulative mortality rate was 82.8%.The cumulative mortality rate was 80.6%,which was significantly higher than other fungal strains,and the LT50 was 3.68d.The dead time is also the fastest.The LT50 and virulence regression equations of the nine different treatments calculated from the raw data also show that other strains are less effective.Therefore,the Bb84 strain of B.bassiana has high potential for the control of B.tabaci.2 Screening of high-efficiency botanical pesticides and optimum concentration of B.tabaciThe indoor efficacy test of different plant-derived pesticides against different species of B.tabaci was carried out,and then the virulence of different plant-derived pesticides to different insect states of B.tabaci was analyzed.The results showed that rotenone and azadirachtin were better in efficacy,and other plant-derived pesticides had poorer efficacy against different species of B.tabaci.Among these two better plant-derived pesticides,azadirachtin on tobacco powder The corrected mortality rate of adult worms was 78.5%,the corrected mortality rate for nymphs was 76.3%,and the corrected mortality rate for whitefly eggs was 84.2%;the corrected mortality rate of rotenone for adults of B.tabaci was 89.2%,for nymphs The corrected mortality rate was 85.5%,and the corrected mortality rate for B.tabaci eggs was 88.5%.The effect of the two on the control of adults and nymphs of B.tabaci was significant,and rotenone had a better effect.The indoor virulence determination method such as leaf immersion method was used to analyze the lethal rate of different concentrations of rotenone on different insect states of B.tabaci.The results showed that 300 times liquid and 200 times liquid had better control effect on B.tabaci,and the other two concentrations had poor virulence to B.tabaci.The cumulative corrected mortality rate of adults was 77.2%when diluted 300 times,the cumulative corrected mortality rate for adults was 1.99 d,the cumulative corrected mortality rate for nymphs was 78.9%,and the time to death for nymphs was 3.48d.81.8%.When the rotenone was diluted 300 times,the cumulative corrected mortality rate of the adult was 78.0%,the time to death of the adult was 1.94d,the cumulative corrected mortality of the nymph was 80.3%,and the time to death of the nymph was 3.41 d.87.8%.Therefore,the two concentrations have a better effect on the control of B.tabaci,because the actual producer considers the cost problem,so the use of rotenone is diluted 300 times as the optimal concentration for laboratory experiments.3 Field investigation and green prevention and control of B.tabaci.Field investigation and bio-pesticide prevention and control experiments were conducted in Pingshan Township,Miyi County,Panzhihua City,Sichuan Province.The results showed that the control experiment of Bemisia tabaci was carried out in the sub-district,and the cumulative mortality rate of B.bassiana was the highest on the 7th day.The control effect of earthworms is good,and Beauveria bassiana has the characteristics of long-term control effect on pests.Therefore,it is recommended to use B.bassiana to control the harm of Tobacco.4 Antagonism between high-virulence entomopathogenic fungi and high-efficiency botanical pesticidesIn order to verify whether rotenone and B.bassiana Bb84 strain can be used in combination,the diameter of the colony was measured by the cross method,and the effect of rotenone on the growth of Bb84 strain was analyzed.The results showed that after the addition of rotenone with dilution ratio of 3000 times,1500 times and 300 times,the average growth diameter of the control group(CK)and the colony with different concentrations of rotenone solution were significantly different after 7 days.The average diameter of colony growth from high concentration to CK was 1.03 cm,1.14 cm,1.41 cm,and 2.04 cm,respectively.Under the condition of 3000 times dilution,it still has a certain inhibitory effect on the growth of B.bassiana.Therefore,rotenone has an inhibitory effect on the growth of B.bassiana Bb84 strain.5 Study on the safety of high-virulence strains of B.tabaci to the larvaeIn order to verify the safety of B.bassiana Bb84 strain to the larvae,the indoor control experiment was used to compare the safety difference between the bacteria and the bacteria-free environment on the larvae of the larvae,and the Bb84 strain of B,bassiana was analyzed.The hatching rate of beetles and the effects of adult mortality.The results showed that the Bb84 strain and the sterile water had no significant difference in the safety of the larvae,and the Bb84 strain had no effect on the hatching rate and adult survival rate of the larvae.Therefore,in the actual production,the simultaneous use of the Bb84 strain of B.bassiana and the method of controlling B.tabaci,which has a broad application prospect.