Efficacy Of Afidopyropen On Controlling Aphis Gossypii And The Biosafety To Hippodamia Variegata

Afidopyropen is a new biological insecticide.It has better control effect on aphids and other piercing-sucking mouthparts pests than mainstream insecticides in market because of resistance,which has great potential for widespread application in crop pest management.Focusing on Aphis gossypii and Hippodamia variegata in cotton field in Xinjiang of China,this study systematically evaluated the toxicity of afidopyropen to A.gossypii and its control effect in cotton field,as well as the biosafety to H.variegata.Bioassay of afidopyropen to A.gossypii and H.variegata were performed by leaf dipping and insect dipping method in laboratory.The results showed that afidopyropen had higher toxicity to A.gossypii,and the corrected mortality rates of A.gossypii were 94.3%and 99.0%after 24 h and 48 h treatments with the highest concentration of 1.6 m L/L,while,the corrected mortality were 68.7%and 76.4%with the highest concentration of 90 m L/L of control agent beta-cypermethrin.The semilethal concentration(LC₅₀)of afidopyropen to A.gossypii was 5.21 mg a.i./L,sublethal concentration of LC₂₀ and LC₁₀ were 1.20 mg a.i./L and 0.56 mg a.i./L,respectively.The toxicity of afidopyropen to H.variegata was low,and the highest corrected mortality of the adults was 3.4%,5.1%and 6.9%,the highest corrected mortality rates of the 3^rdinstar larvae were 6.3%,14.4%and 18.3%after 24 h,48 h and 72 h with afidopyropen application respectively.Howerver,the corrected mortality rates were over 99%after the control agent beta-cypermethrin application,indicated significantly difference with afidopyropen application.Field experiments demonstrated that afidopyropen had a better control effect on A.gossypii,and the corrected control effect was the highest（85.3%）with the highest concentration（24 ml/mu）on the 14^th day application,which was significantly higher than beta-cypermethrin treatment（the application concentration of 90 ml/mu）with the corrected control effect at-131.0%（a resurgence of aphids）.Afidopyropen had less negative effect on H.variegata population in field,and the ratio of predator to aphids with 24 ml/mu application had no significant difference to water control except the 1^st day after application.Considered with effect on controlling A.gossypii,H.variegata population and economic benefit,6 ml/mu（30 kg/mu）application was recommended for control of A.gossypii.Life table detection showed that the semilethal(LC₅₀)and sublethal(LC₁₀,LC₂₀)concentration of afidopyropen had less negative effect on fecundity of female H.variegata（F₀）and most life parameters of F₁ Generation.The pre-oviposition period of female H.variegata was 2.4 d,and fecundity per day（in eggs）was 18.1 after semilethal(LC₅₀)application,which were both not significantly different with water control（2.1 d,19.8）.The hatchability,eclosion rate and pupal weight of F₁ were 73.3%,95.3%,and 10.8 mg,respectively,which had no significant difference with water control（85.8%,97.1%,11.4 mg）.In addition,adult sex ratio of F₁ had no significant difference in different treatments.However,the developmental duration of the 1^st instar larvae of F₁ was slightly increased with concentration of afidopyropen increase and reached 3.5 d under the LC₅₀concentration application,which was significant longer than the control group（2.4 d）.It was found that the semilethal and sublethal concentration of afidopyropen had weakly effects on the predation ability of H.variegata to A.gossypii,and its predation function was corresponded with HollingⅡmodel.Prey consumption of H.variegata to A.gossypii was slightly various in different treatments,and it increased with prey density increase.Variation of searching efficiency was the same with insecticide application and control,and it declined with prey density increase.Besides,caged experiments showed H.variegata had better control efficiency on A.gossypii and there were no disadvantages on biocontrol of A.gossypii.Combinated the chemical application and biological pest control will be benefit and get a better control efficiency on A.gossypii.Flight-mill test showed that the semilethal and sublethal concentration of afidopyropen had less negative effect on the flight ability of H.variegata.The flight speed,time and distance of female H.variegata after24 h with LC₅₀ treatment of afidopyropen were 288.6 m/h,0.64 h,187.7 m,which showed no significant difference compared with the control group（336.9 m/h、0.78 h、231.2 m）.Male flight ability was less than female in all treatments.In conclusion,afidopyropen has a high toxicity on A.gossypii and can effectively reduced aphid population density of in cotton field.Moreover,it has a low toxicity to the predator-H.variegata,and has no significant negative effects on its development,fecundity,predation function and flight ability.Therefore,afidopyropen could be considered widely application in cotton fields of Xinjiang.