Toxicity Of Six Insecticides And Effect Of Flupyradifurone On Growth,Reproduction And Gene Expression In Diaphorina Citri(Kuwayama)

Diaphorina citri?Kuwayama?belongs to the Insecta,Hemiptera,and Liviidae families.It is a citrus pest that is distributed in many countries around the world.D.citri is an important vector insect for transmitting HLB.HLB is one of the most devastating diseases in citrus industries in the world.Therefore,the management of D.citri is the key way for control of HLB.Chemical control of D.citri is one of the effective way to curb the spread of HLB.However,D.citri has developed resistance to some common insecticides due to the long-term unreasonable use of pesticides.Studying the resistance mechanism of D.citri can help to control its damage more effectively.In this test,the virulence of 6 insecticides to D.citri at different temperatures,the sublethal effect of flupyradifurone on D.citri,and the gene expression profile and differential gene analysis of D.citri in response to flupyradifurone stress were researched.The aim is to find out the effect of flupyradifurone on D.citri,to point out the direction for efficient control of D.citri,and to provide a reference for pesticide field application and D.citri resistance monitoring.The main results obtained in this study are as follows:1.Toxicity of 6 insecticides to D.citri at different temperaturesThe virulence of six insecticides on D.citri adults and nymphs at different temperatures was measured by the membranous film method and the leaf dipping method.The results showed that at 18,22,26,30,and 34?,the LC50 values for D.citri adults of flupyradifurone were 5.85,6.05,8.81,13.01,and 14.97 mg/L;the LC₅₀0 values for D.citri adults of spirotetramat were 746.58,121.21,84.73,67.39,and39.94 mg/L;the LC₅₀0 values for D.citri adults of thiamethoxam were 91.10,88.55,81.06,54.36,and 50.56 mg/L;the LC₅₀0 values for D.citri adults of dinotefuran were14.32,28.19,37.38,29.83,and 25.01 mg/L;the LC₅₀0 values for D.citri adults of bifenthrin were 7.09,5.94,5.04,7.63,and 4.71 mg/L;the LC50 values for D.citri adults of chlorpyrifos were 36.06,79.40,129.65,59.96,and 89.70 mg/L.That was to say,in the range of 18-34?,flupyradifurone had a negative temperature effect on D.citri adults,spirotetramat and thiamethoxam had a positive temperature effect on D.citri adults.Dinotefuran,bifenthrin,and chlorpyrifos had no significant temperature effect on D.citri.adults.At 18,22,26,30,and 34?,the LC₅₀0 values for D.citri nymphs of flupyradifurone were 4.34,5.11,6.46,7.90,and 8.92 mg/L,respectively;the LC50values for D.citri nymphs of spirotetramat were 62.25,50.75,30.27,28.17,and 28.08mg/L,respectively;the LC₅₀0 values for D.citri nymphs of thiamethoxam were 23.04,19.21,18.29,11.93,and 10.25 mg/L,respectively;the LC50 values for D.citri nymphs of dinotefuran were 31.96,26.59,25.10,16.85,and 6.13 mg/L;the LC₅₀0 values for D.citri nymphs of bifenthrin were 2.77,5.93,7.75,6.17,and 8.84 mg/L;the LC₅₀values for D.citri nymphs of chlorpyrifos were 9.61,16.21,17.28,26.44,and 48.32mg/L.That was to say,in the range of 18-34?,flupyradifurone has a negative temperature effect on D.citri nymphs,spirotetramat has a positive temperature effect on D.citri nymphs,and thiamethoxam has a positive temperature effect on D.citri nymphs.It was same as adults.In addition,dinotefuran has a positive temperature effect on D.citri nymphs,chlorpyrifos has a negative temperature effect on D.citri nymphs,and bifenthrin has no significant temperature effect on D.citri nymphs.Moreover,in the six commonly used insecticides,both D.citri adults and nymphs are most sensitive to flupyradifurone and bifenthrin.2.Effect of sublethal concentration of flupyradifurone on growth and reproduction of D.citriThe D.citri was treated with LC₄₀0 and LC₂₀0 concentrations of flupyradifurone by the bagging method.The egg production,egg hatching rate,and developmental period of the D.citri were observed and recorded,and the egg and nymph stages were counted.The data shows that under the lethal concentration stress of flupyradifurone,the spawning rate and hatching rate of D.citri were significantly reduced.The LC40 of flupyradifurone treatment group had spawning rate?26.00?and hatching rate?41.03%?.The results showed that with the increase of flupyradifurone concentration,the egg production and egg hatching rate of D.citri decreased significantly;the egg duration was slightly extended,but there was no significant difference;nymph stage significantly longer.Therefore,flupirone affects the growth and development of D.citri,reduces egg production and egg hatching rate,and prolongs the egg and nymph periods.3.Analysis of expression profiles and genes related of D.citri in response to flupyradifurone stressIn this experiment,the transcriptomes of two samples of D.citri control and flupyradifurone treatment groups were sequenced,2028 differentially expressed genes were analyzed,including 1433 genes up-regulated and 595 genes down-regulated.A total of 2028 differential genes were annotated,of which 1133 were annotated in GO database and 847 were annotated in KEGG database.Ten genes were screened from them for real-time quantitative PCR.The results showed that at different concentrations of LC₁₀,LC₃₀0 and LC₅₀,Gene103521146 upregulation multiples were1.35,16.31,1.42;Gene103505377 upregulation multiples were 2.24,6.86,4.77;Gene103510516 upregulation multiples were 1.54,5.62,1.58;Gene103524870 down regulation multiples were 9.09,19.73 and 9.92;Gene103506912 down multiples were8.53,5.55 and 3.49;Gene103524880 down multiples were 3.76,9.95 and 3.53;Gene103520212 down multiples were 10.75,30.03 and 3.37;Gene103511693 down multiples were 3.50,7.55 and 2.59 respectively;Gene103522354 down multiples were13.70,23.14 and 7.00;Gene108253343 down multiples were 5.78,8.86 and 7.02respectively.Among them,when the concentration of LC10 is treated,Gene103505377has the largest upward adjustment factor,and Gene103522354 has the largest downward adjustment factor;when concentration LC30 is processed,Gene103521146has the highest upward adjustment factor,and Gene103520212 has the largest downward adjustment factor;when concentration LC₅₀0 treatment,Gene103505377 has the highest upward adjustment factor,and Gene103524870 has the largest downward adjustment factor.