Preliminary Study On The Control Of Tomato Whitefly By Triolei

Tomato(Solanum lycopersicum L.)is a crop of Tomato in Solanaceae.It is one of the vegetables widely planted all over the world.Tomato is damaged by a variety of diseases and pests.At present,chemical pesticides are mainly used for control,but a series of problems such as damage to tomato growth,threat to tomato food safety and drug resistance arise.Therefore,tomato planting urgently needs green and safe pest control methods.Vegetable oil insecticide is a green pesticide,but its control efficiency is low,so it is not widely used as an insecticide,but the content of triglyceride,one of its main components,is positively correlated with the insecticidal effect.In this study,Bemisia tabaci,the main pest of tomato,was used to develop the agent by using the purified triglyceride,and the appropriate emulsifier was selected.The effects of triglyceride on Tomato Growth(plant height,stem diameter,photosynthetic pigment and resistance index)and volatile substances(composition and content change)of tomato,as well as its virulence and repellent effect on Bemisia tabaci,were explored in order to optimize the concentration of triglyceride,screen the concentration of triglyceride insecticide suitable for tomato,and develop a new type of triglyceride insecticide with high efficiency,green and environmental protection,It is of great significance for the control of tomato Bemisia tabaci.At the same time,it provides technical and product support for tomato green planting.The main research contents of this paper are as follows:1.Screening of insecticides for controlling Bemisia tabaciThrough the analysis of fatty acid components of 7 kinds of vegetable oils,it is concluded that the fatty acid components with high content are linoleic acid or oleic acid,accounting for more than 60% of the total.The HLB value of triglyceride(97%)was determined by emulsification method and the emulsifier was selected.The HLB value of triglyceride(97%)was 8.5.When the emulsifier AEO3,np4 and Tween80 were mixed,the mass ratio was 1:1:0.015 and the addition amount was10%,the emulsification was stable;Finally,considering the production cost of newly developed pesticides and the stability of pesticides,the crude oil of triglyceride(97%)was selected for development,and finally a new agricultural spraying oil product-90% triglyceride(97%)emulsion was developed.2.Effects of triglyceride on physiological indexes and volatiles of tomatoBy measuring the biomass of tomato plants,it was found that the external application of appropriate amount of triglyceride could promote the growth rate of plant height and stem diameter,so as to promote the growth and development of tomato.Appropriate concentration of triglyceride can promote the synthesis of photosynthetic pigment.Triglyceride can significantly increase the content of photosynthetic pigment in tomato leaves at 3,6 and 9 days after treatment.Through the determination of antioxidant enzyme activity,it was found that the SOD activity increased significantly when treated with 0.5% and 0.25%triglyceride on the 3rd,6th and 9th days.The treatment of 0.5%,0.25%,0.125% and 0.1% triglyceride on the 3rd,6th and 9th days had significant differences with the blank control group,and could significantly improve the POD activity of tomato leaves.The change of CAT activity of tomato leaves was the same as that of POD activity.In addition,when 0.5%triglyceride was applied externally,the growth rate of plant height,stem diameter,photosynthetic pigment content and antioxidant enzyme activity increased the most.At the same time,through the volatile identification of tomato leaves treated with different concentrations of triglyceride,it was found that there were differences in the content of volatile substances in each group.A total of 32 VOCs were found in the treatment group,of which 16 volatile substances had significant differences.In addition,the content of many terpenoids in the volatile substances in the triglyceride treatment group was significantly higher than that in the control treatment group.3.Lethal effect of triglyceride on Bemisia tabaciThe virulence of triglyceride to Bemisia tabaci at each age(expressed by LC50)from strong to weak was adult,old nymph,young nymph and egg;The toxicity of triglyceride to Bemisia tabaci increased with the increase of concentration and time.The toxic effect of trioleic acid glyceride(32187.299 mg/l)on whitefly eggs was stronger than SK mineral oil(18096.070 mg/l),and the difference was significant.The toxicity of triglyceride to the adults of Bemisia tabaci was stronger than that of SK mineral oil,and the LC50 values after treatment were 167.156 and 354.541mg/l respectively.4.Repellent effect of triglyceride on Bemisia tabaciThe "Y" tube was used to determine the effect of triglyceride on the behavior of Bemisia tabaci.The results showed that triglyceride had repellent effect on Bemisia tabaci after treatment for 1,4,7 days and 1hour.Triglyceride and SK mineral oil had obvious repellent effect on Bemisia tabaci after treatment for 1 hour and 1 day.The difference was significant,but the repellent rate of triglyceride was large(76.00% and64.37% respectively).After 4 days of treatment,the repellent effect of mineral oil was stronger than that of triglyceride(the repellent rate was47.23%),and there was no difference between triglyceride and SK mineral oil.After 7 days of treatment,the repellent effect of triglyceride was weakened.The repellent rate of triglyceride was only 35.54%,and that of SK mineral oil was 40.69%.