Insecticide Selection And Decrement And Synergism Of Controlling Aphis Gossypii By Unmanned Aerial Vehicle

Aphis gossypii is one of the main pests in cotton production.In recent years,it has caused an outbreak in southern Xinjiang.Due to its small size,fast reproduction speed and strong adaptability,it is difficult to prevent and control.At present,the control of Aphis gossypii is still manual and semi-mechanized,which is not only inefficient,but also can't solve the problem of Aphis gossypii outbreak and spread in a short time in cotton fields in Xinjiang.Plant protection technology by Unmanned Aerial Vehicle(UAV)has been gradually accepted by cotton farmers for Aphis gossypii prevention and control due to its high efficiency,convenient operation,no secondary damage to crops,drug saving and water saving.However,UAV plant protection technology in the control of Aphis gossypii,due to the complex and changeable operating environment,mostly based on experience or reference to the ground spray to determine the dose and configuration method,resulting in poor spraying operation efficiency and operation effect,also easy to cause a large negative impact on the environment.Therefore,this paper studies the change of temperature and humidity in the cotton field in southern Xinjiang and the rule of occurrence and growth of Aphis gossypii,and grasps the rule of occurrence and harm of Aphis gossypii in the cotton field,so as to provide basis for the establishment of plant protection unmanned aerial vehicle to prevent and control Aphis gossypii in the critical period.According to the characteristics of low-altitude and low-capacity spraying,the droplet settlement law,flight control parameter measurement and low-altitude pesticide application technology of UAV in cotton field were studied.The toxicity and selectivity of various insecticides on Aphis gossypii and Coccinella undecimpunctata were studied by combining indoor and field experiments,so as to provide a basis for reducing pesticide use and improving ecological and economic benefits.The results are as follows:1.A preliminary study on the temperature and humidity and the occurrence rule of Aphis gossypiiThe results showed that: Aphis gossypii first moved into the cotton field from late April to early may,the temperature was 18 ~ 28?,the humidity was 5%-10%,the percentage of Aphis gossypii was less than 5%,and the total Aphis gossypii amount of 100 plants was no more than 30.With the increase of temperature,the Aphis gossypii population reached its peak in late June,when the average temperature was 31-33?and the humidity was 18%-30%.The percentage of Aphis gossypii reached more than 95% and the average amount of 100 plants was about 28786.In late July,cotton entered the flower-boll period,and cotton plants gradually changed from vegetative growth to reproductive growth.The number of Aphis gossypii began to gradually fade,with an average temperature of 29 ~ 32?and a humidity of 17%-23%.The percentage of Aphis gossypii was 30% ~ 60%,and the average number of Aphis gossypii per plant is 8031.2.Effects of MG-1P unmanned aerial vehicle spray parameters on the droplet deposition distribution of cotton canopy and the control effect of Aphis gossypiiIn order to clarify the distribution pattern and control effect of cotton aphid by MG-1P unmanned aerial vehicle on cotton canopy,the effective spray range under different flight parameters and the distribution pattern and control effect of cotton aphid were studied.The results show that the effective spray width is 4.7m with the highest droplets density and the best droplets uniformity and the best cotton effect which is 96.83% when the flying height is 2.5m.Considering the distribution characteristics of the droplet deposition and the control effect of Aphis gossypii,the best spray parameters should be 2.5m flying height and 4.7m spray width.3.Toxicity determination of insecticides to Aphis gossypii and Coccinella undecimpunctataThe result of the toxicity measuremen showed that the highest toxicity to Aphis gossypii among the five pesticides was 5% Dipropyl cycloester DC,which was 24.71 in 48h-LC50,and 46% Acetamiprid WG came second,the 48h-LC50 value was 34.50,70% Imidacloprid WG had the lowest virulence to Aphis gossypii,48h-LC50 is 17.43,but the highest virulence to Coccinella undecimpunctata was 70% Imidacloprid WG,48h-LC50 was 131.38,and 5% Dipropyl cycloester DC had the lowest virulence against Coccinella undecimpunctata,1083.39 at 48h-LC50,the ratio of selective virulence for different agents(Coccinella undecimpunctata LC50/Aphis gossypii LC50)was 5% Dipropyl cycloester DC31.69>46%Acetamiprid WG>22% Sulfoxaflor SC>65%Pymetrozine WG>70% Imidacloprid WG.4.Study on insecticide screening of controlling Aphis gossypii by UAV8 kinds of pesticides were sprayed by UAV to screen out the best pesticides on controlling Aphis gossypii and make further efforts to conduct a reduction test to determine the effect after the reduction.The results showed that 22% Sulfoxaflor SC and 70% Imidacloprid WG had the best control effect on Aphis gossypii,96.2% and 92.4% respectively after 7d.22% Sulfoxaflor SC and the 70% Imidacloprid WG reduction test showed that the prevention effect was 75.1% and 70.2% when the conventional dosage was reduced by 10% and 20%,which was no significant difference from the conventional dosage(CK),but when the reduction was 30%,the prevention effect was 51.6% and 64.7%,which was significantly different from the control after 7days.The prevention effects were 87.1% and 54.5%,respectively after 15 days when two insecticide were reduced by 10%.No significant difference from conventional dosage,while other reduction treatments were significantly different from conventional dosage(CK).In production practice,it was recommended that 22% Sulfoxaflor SC was reduced by 10% and sprayed once every 15 days,which could achieve the same control effect as conventional spraying.70% Imidacloprid WG was reduced by 20% per spraying once every 7d,it could achieve the same control effect as conventional spraying.