| The serious harm caused by chemical pesticides to the ecological environment,biosafety and biodiversity has become increasingly prominent.Green prevention and control technologies with non-chemical prevention and control as the main content have attracted more and more attention.The phototaxis of insects is used to prevent and control agricultural pests.Technology has been widely used.However,with the widespread use of insect traps,it has been found that while trapping insects kills insects,it also kills natural enemy insects and other non-target neutral insects by mistake,even if the trap has a natural enemy escape system.B.tabaci is one of the important pests on greenhouse cucumbers.The serious damage often causes the cucumber production to decrease and even destroys the shed.This paper screened the light with repellent effect on B.tabaci,explored the control effect of repellent light on B.tabaci and the mechanism of inducing insect resistance to main vegetables,and provided a new method for the green prevention and control of B.tabaci on cucumber.The main findings are as follows:1.Use the relationship between the RGB value and the virtual wavelength,the colors of different wavelengths are simulated on the computer,and the sensitive colors that can repel B.tabaci are selected.On this basis,the effect of light on the population of cucumber B.tabaci in the facility is studied.The study found that blue light with a wavelength of 470 nm has a strong repellent effect on B.tabaci adults,while yellow(54.00%)and green(42.00%)have a strong trapping effect on B.tabaci.By adding blue light to yellow light and green light environment,the selectivity of B.tabaci to yellow light(68.00%)and green light(56.00%)is increased by 33.33%and 16.67%respectively;while in the environment where yellow light and green light coexist.With the addition of blue light,the selectivity of B.tabaci for yellow light increased to 70.00%,which was significantly higher than the selectivity for green light(24.00%).Direct light and transmitted light repellent tests show that direct light has a stronger repelling effect than transmitted light under the same light intensity and illumination time.After 1200 Lux blue light is directly exposed to B.tabaci for 5 minutes,the population reduction rate of B.tabaci is 77.70%.It is 17.40%higher than the transmitted light.After 2 minutes of direct exposure to 1750 Lux blue light,the insect population reduction rate is 41.20%,which is 10.60%higher than that of the transmitted light.2.Potted plants and field production conditions were used to study the control effect of blue light on B.tabaci on cucumber.The results showed that blue light irradiation also had a better repellent effect on B.tabaci on cucumber leaves during seedling stage.The corrected population reduction rate of the whitefly population reached 88.5%.Placing a blue light strip in a cucumber field in a greenhouse found that the population of B.tabaci on cucumbers decreased rapidly after blue light exposure,and with the prolongation of light exposure,the number of B.tabaci on cucumbers decreased significantly.After 6 d of light exposure The corrected population reduction rate of B.tabaci reached 92.76%;turn on the yellow light before turning on the blue light,and turn on the blue light after 30 minutes to turn off the yellow light.It was found that the combined use of blue light and yellow light can enhance the control effect on the cucumber B.tabaci population.10 After 10 d,20 d,and 30 d,the corrected population reduction rate of B.tabaci on cucumber leaves increased by 13.80%,19.17%,and 15.10%,respectively.The repellent effect of blue light on B.tabaci adults is positively correlated with light intensity and light time.The greater the light intensity and the longer the exposure time,the stronger the repellent effect on B.tabaci.The direct repellent test shows that the greater the light intensity and the longer the irradiation time,the stronger the repellent effect on B.tabaci;the direct light has a stronger repellent effect than the transmitted light under the same light intensity and light time.The 1200 Lux blue light direct smoke After 5 minutes,the population reduction rate of B.tabaci was 77.70%,which was 17.40%higher than transmitted light.After 2 minutes of direct exposure to 1750 Lux blue light,the population reduction rate was 41.20%,which was 10.60%higher than transmitted light.3.Use blue light to irradiate potted cucumbers indoors to study the effects of blue light on the growth and development of related substances in cucumbers and B,tabaci.The results showed that the soluble sugar,free protein,total phenols,and flavonoids in cucumber leaves increased by 70.80%,50.00%,48.30%,and 81.80%compared with the control,and proline decreased by 129.50%compared with the control.Volatile substances related to B.tabaci resistance:trans-β-famesene,trans-2-hexenal,cis-4-heptenal,trans β-ocimene,D-carvone,Peroxidase(POD),catalase(CAT),ultra-premium peroxidase(POD),catalase(CAT),and peroxidase(POD)increased respectively by 1.60 times,9.90 times,7.00 times,1.70 times,142382811.50 times,3.00 times and 10665412.50 times compared with the control.Oxide dismutase(SOD)and ascorbate peroxidase(APX)were increased by 75.00%,130.60%,22.40%,and 51.70%,respectively,compared with the control.The duration of the emergence of B.tabaci from egg to adult was longer after 8 hours of blue light irradiation per day.The control was extended by 4.0%,and with the extension of blue light irradiation time,the development period of B.tabaci was extended.4.The results showed that the first principal component of 3-hexene-1-alcohol,which had the trapping effect on the planthopper,decreased with the increase of blue light irradiation time.After blue light treatment,389 metabolites were detected,23 of which showed an upward trend,15 substances showed a downward trend,and 17 metabolites appeared in leaves.Ketones and olefins had a significant increase in the repellent effects of whitefly.Blue light irradiation also had a significant effect on the metabolism pathway of cucumber.The experiment found that 24 metabolic pathways had significant changes,including secondary metabolite synthesis pathway,carbon metabolism,amino acid synthesis,flavonoid and flavonol biosynthesis,monoterpenoid biosynthesis,sesquiterpene and triterpene biosynthesis,which were closely related to the insect resistance of B.tabaci.5.Trans-2-hexenal played a very important role in promoting cucumber to repel B.tabaci.In order to further explore the related genes that regulate the expression of trans-2-hexenal,molecular biology techniques are used to carry out relevant screening and silencing treatments.According to the expression level of volatiles before and after silencing and the results of the olfactory response measurement results,the trans-2-hexenal is clarified.Regulatory genes for alkenals.Studies have found that the trans-2-hexenal of cucumber is mainly regulated by hydroperoxide lyase(HPL).The blue light irradiation time was positively correlated with the HPL activity in cucumber leaves.The HPL enzyme activity(0.092 U)after 8 h of blue light treatment was 143.75%of the control(0.0694 U).It is the HPL-9/13 gene that blue light irradiation plays a key regulatory role in HPL,and its change trend is consistent with the change trend of HPL enzyme.Through the construction of the RNAi vector and genetic transformation of this gene,two transformed cucumber seedlings were successfully obtained,and the silencing efficiency reached 88.00%.Through GC-MS measurement of RNAi cucumber seedling leaves,it was found that the volatile amount of trans-2-hexenal in the control cucumber seedlings(1.56%)was 13 times that of RNAi cucumber seedlings(0.12%).The olfactory experiment also found that the selection rate of the adult B.tabaci on RNAi cucumber seedlings(68.00%)was 1.13 times higher than that of the control(32.00%).The results showed that the HPL-9/13 gene is related to cucumber resistance to B.tabaci. |
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