| As a major pest with seasonal long-distance habitat,Cnaphalocrocis medinalis is one of the main pests of rice in Fengtai County.It occurs frequently in rice production areas in China,and the extent of hazard is extremely serious.It has caused a serious threat to the production safety of rice.At present,chemical prevention is sill the main method to control C.medinalis.Although most of the chemicals used are low-toxic pesticides,they still have great influence on the environment and natural enemies.Therefore,it is of great significance to grasp the occurrence law of C.medinalis clearly,to study green control technology and to screen high-efficiency,safe,low-toxic and low-polluted chemicals.In this study,the occurrence law of C.medinalis in Fengtai County was studied,and a set of green control method was explored.The results were as follows:(1)Study on the occurrence law of C.medinalis in Fengtai CountyThe occurrence law has been summarized by analyzing the historical data of C.medinalis occurred from 2011 to 2020 in Fengtai County,Huainan City,Anhui Province.The result showed that C.medinalis mainly migrated to Fengtai County in early July.But there was an earlier trend in recent three years,which should be prevented in advance.There were 3 generations occurred in Fengtai,of which the fifth(3)generation and six(4)generation were the main harmful generations.The degree of occurrence over the years was mild to moderate,and the occurrence characteristic was that the occurrence of fourth(2)generation to sixth(4)generation was getting more and more severe,with a sporadic occurrence in the fourth(2)generation,a mild occurrence in the fifth(3)generation and mild to moderate occurrences in the sixth(4)generation.The occurring extent of Six(4)generation is more serious than other generations,so it is necessary to control the moth peak period,egg hatching peak period and low age larvae peak period by using insecticides in time and properly.(2)Screening of highly effective insecticides to control C.medinalisThe toxicity and field efficiacy of 8 insecticides such as 20% Emamectin·indoxacarb SC,200g/L Chlorophenamides SC,1.8% Avermectin EC were studied.The results of virulence test showed that all the 8 insecticides had high toxicity to C.medinalis.The toxicity order wasas follows:5% Emamectin benzoate SL> 1.8% Avermectin EC >34%Spinetoram·Methoxyfenozide SC >20% Emamectin·indoxacarb SC>200g/L Chlorophenamides SC>10%Tetrachlorantraniliprole SC>40%Thiamethoxam·chlorantraniliprole SL> 15% Indoxacarb EC.They all showed higher differences to 48% Chlorpyrifos EC.he results of field experiments showed that all the 8insecticides had good control effects on C.medinalis.Among them,20% Emamectin · indo xacarb and 200g/L Chloranbenzoamide had the best control effect,98.86% and 98.25%after 14 days of treatment,respectively.1.8% Avermectin emulsion had the worst control effect,89.82% after 14 days of treatment.All the 8 tested insecticide had no harm to rice in the range of experimental dose.It was suggested that they should be used alternately or rationally mixed in production practice.(3)Study on green control technology to C.medinalisThe control effect of 4 single green control technologies(Frequency vibration solar insecticidal lamp,Sex pheromones trap,Trichogramma releasing and 16000IU/mg Bt WP)and green integrated technologies of their combination were compared against C.medinalis.The results showed that the control effect of 16000IU/mg Bt WP showed significantly higher than the other three methods.The control effects of frequency vibration solar energy insecticide lamp,Sex pheromones trap and Trichogramma releasing were 47.54%,43.03% and 57.84%,respectively,which were not ideal and could not be used as a separate method.They were suggested to use with other methods.Among the green integrated technologies,the combinations of Trichogramma + Bt and Insecticidal lamp + Bt had the best control effects,which were 93.62% and 91.32%,respectively,no difference with chemical control area.The control effects of Sex pheromones trap +Trichogramma,insecticidal lamp + Trichogramma,Sex pheromones trap + Bt had better control effects,which were all above 83%.The control effect of Sex pheromones trap +insecticidal lamp was poor,only 74.61%,and it was suggested to be used as a supporting technology to other control technologies.Based on the occurrence law of C.medinalis in Fengtai county,the control strategy to Fengtai county is put forward,namely,reducing the source base of fifth(3)generation,and focusing on the control of sixth(4)generation.It is suggested to keep accurate prediction,grasp the suitable period for larval control,use insecticides precisely and comprehensive use of various green integrated prevention and treatment technologies. |
PDF Full Text Request