Research On Chemical Control Technology For Fall Armyworm With Reduced Pesticide Use And Increased Efficienc

Spodoptera frugiperda is a migratory pest native to the tropical and subtropical regions of the Americas.It has the characteristics of strong drug resistance and hidden early damage.At present,it has caused serious harm to corn and other major crops in China.In this experiment,through the field investigation of the occurrence law of Spodoptera frugiperda,indoor toxicity test and field application test,the control agent,application time and application method of Spodoptera frugiperda were discussed,and the key technology of chemical control of Spodoptera frugiperda was refined.The control law of Spodoptera frugiperda in the Three Gorges Reservoir Area of Chongqing was studied to achieve the goal of reducing pesticide and increasing efficiency.The main results are as follows:（1）There were three damage peaks of S.frugiperda from sowing to tasseling stage in the Three Gorges Reservoir area of Chongqing.The first peak time was from the end of April to the beginning of May,and the insect strain rate was below 1%.The second peak was the corn bellmouth period in early and middle June,and the insect plant rate was 30%～50%.The third peak occurred in the silking stage of maize in early July,mainly damaging filaments and young spikes,and it was found that the second peak of the elderly larvae in the region overlapped with the third peak of the young larvae.（2）The results of leaf-dipping toxicity test showed that 5%emamectin benzoate had the highest indoor toxicity to S.frugiperda（4th-5th instar larvae）,with48h LC₅₀of 3.193mg/L,followed by 8%chlorfenapyr and 5%chlorantraniliprole with 48h LC₅₀of 153.555mg/L and 223.101mg/L.The toxicity of 25g/L deltamethrin and 5%lufenuron was low,with 48h LC₅₀of 830.532mg/L and 1199.584mg/L,respectively.The results of indoor toxicity test showed that 5%emamectin benzoate had the highest indoor toxicity to Spodoptera frugiperda（2-3 instar larvae）,with 24h LC₅₀of 0.201mg/L,followed by 25g/L deltamethrin and 8%chlorfenapyr,with 24h LC₅₀of 8.499mg/L and 27.419mg L.The indoor toxicity of 5%lufenuron and 5%chlorantraniliprole was weak,with 24h LC₅₀of 66.983mg/L and 121.705mg/L,respectively.In the field pesticide screening test,chlorantraniliprole,emamectin benzoate and chlorfenapyr were determined as field pesticide reduction and synergistic agents.（3）The proportion of S.frugiperda larvae in the first peak of damage in the Three Gorges Reservoir area is low and difficult to observe.Under normal circumstances,one application of S.frugiperda can be reduced,and the second peak of damage can be focused on.（4）The results of the application effect test of different application methods showed that the artificial sprayer sprayed the pesticide>the chemical sanding snack>the UAV sprayed the pesticide.Among them,the effect of artificial spraying pesticides was the best,and the population decline rate reached 89.86%,while the effect of UAV spraying pesticides was the worst,and the population decline rate was only 49.91%.（5）The results of pesticide reduction and efficiency test showed that the control effect of 6g of emamectin benzoate per 667m²on the larvae of S.frugiperda reached92.74%.The control effect of 4g emamectin benzoate+20g ethylene glycol was91.54%per 667m²,the control effect of 14g chlorantraniliprole was 93.64%per667m²,and the control effect of 10g chlorantraniliprole+20g ethylene glycol was95.4%per 667m².（6）The use of drug reduction and efficiency technology,every 667m²can reduce 0.25 labor,reduce labor costs 25yuan;in the case of adding ethylene glycol as pesticide adjuvant,compared with the recommended dosage,the dosage was reduced by more than 30%,and the cost of each 667m²was 2.4～5.5 yuan,which was reduced by nearly 50%.At the same time,the control effect on S.frugiperda was enhanced,and the control effect reached more than 90%,which greatly increased the economic benefits of corn farmers.