The Occurrence Regularity Of Corn Borer And The Application Of Use Reduction And Efficiency Enhancement Of Insecticide In Shanxi Province

The corn borer,as a source of damage to major crops such as corn and sorghum,has been widely harmed in China in recent years,with a long duration of damage.It can even continue to damage the entire growth cycle of corn plants,directly leading to an increase in the rate of corn hollow stems and the aggravation of diseases such as ear rot.There is a general lack of professional guidance in corn cultivation in Shanxi region,resulting in the frequent occurrence of indiscriminate and excessive use of drugs.Not only is it difficult to ensure com yield and quality,but there are also serious problems such as excessive drug residues and strong pest resistance in the environment,which has brought significant ecological and agricultural development pressure to Shanxi region.Therefore,only through professional and precise unified control of the corn borer can the harm be minimized and the loss of yield and ecological environment be recovered.This article will lay a solid foundation for ensuring the long-term and efficient prevention and control of corn borers by conducting monitoring of their occurrence dynamics and conducting relevant experiments on drug reduction and enhanced control techniques in the Shanxi region.For two consecutive years,the dynamics of the occurrence of corn borers in Datong,Changzhi,and Linfen monitoring points in Shanxi Province were monitored.The results showed that the overwintering population of corn borers in Datong in 2020(34.00 heads/100 stems)was not significantly different from that in Changzhi(32.00 heads/100 stems),and the survey in 2021 also showed similar conclusions.The overwintering population of corn borers in Datong in that year(45.00 heads/100 stems)was slightly lower than that in Changzhi(49.00 heads/100 stems),However,the number of adult corn borers in both regions in 2021 was higher than the same period in 2020.The overwintering numbers of corn borers at monitoring points in Linfen in 2020 and 2021 were 48.00 heads/100 stems and 61.00 heads/100 stems,respectively,which were significantly higher than the monitoring data in Datong and Changzhi in the same year.In the past two years,the average total adult population of corn borers in Linfen was 284.75 heads/lamp and 331.00 heads/lamp,respectively,which were 1.64 times and 1.32 times the corresponding values for Datong(173.75 heads/lamp)and Changzhi(215.00 heads/lamp)in 2020,and 1.71 times and 1.34 times the corresponding values for Datong(193.25 heads/lamp)and Changzhi(246.25 heads/lamp)in 2021.This is closely related to their relatively high overwintering base.In 2021,the flower and leaf rates in Datong,Changzhi,and Linfen were as high as 15.0%,18.0%,and 23.5%,respectively.Compared with 14.0%,12.5%,and 19.0%in 2020,the damage of corn borers in all three monitoring points showed a trend of increasing weight,especially in Linfen,where the severity of corn borer damage was much greater than in Datong and Changzhi.This article selected four commonly used insecticides,including indoxacarb,phoxim,bromocyanilamide,and chlorpyrifos,for indoor toxicity testing and resistance level monitoring of corn borers.The toxicity test results showed that the toxicity effects of the four insecticides were 40%phoxim emulsifiable concentrate>10%bromocyanilamide>35%chlorpyrifos>150mg/L indopyrifos,with 150mg/L indopyrifos(LCso is 0.072mg/L)having the worst toxicity effect 48 hours after treatment,35%chlorpyrifos benzamide(LC50:0.050mg/L)showed a slightly enhanced toxicity effect on corn borers,while 40%phoxim emulsifiable concentrate(LC50:0.009 mg/L)and 10%bromocyanoxamide(LC50:0.023mg/L)showed strong toxicity,with toxicity 8.0 and 3.13 times higher than 150mg/L indoxacarb,respectively.From the monitoring results of resistance level,it can be seen that the corn borer population in Datong area has shown moderate resistance to 150mg/L imidacloprid(RR=40.57),while the corn borer population in Changzhi area has shown low level resistance(RR=8.05)and moderate level resistance(RR=13.74)to 10%bromocycloprid and 150mg/L imidacloprid.The corn borer population in Linfen mainly has moderate level resistance to 10%bromocycloprid(RR=25.49),The corn borer populations in Datong and Linfen showed sensitivity to 35%chlorpyrifos(RR 2.82,2.58,respectively),while the Changzhi population showed a decrease in sensitivity(RR 4.77).The corn borer populations at the three monitoring points showed the highest sensitivity to 40%phoxim emulsifiable concentrate,with RR 0.20,0.39,and 4.73,respectively.Therefore,they can become the preferred corn borer control agent in Shanxi region.In the study of drug reduction and efficiency enhancement,it was found that the two synergists"Jinjian" and "Huifeng" had control effects on corn borer at 84.18%and 86.16%,respectively.Their control effects were not significantly different from those without drugreduction treatment(85.94%),and when adding 10.00mL/667 m2 Huifeng,their control effects were also enhanced to some extent;The control effect of adding synergists at a 30%reduction level is 74.96%～79.43%,which is about 7.81%～10.95%lower than the control effect of reducing drugs by 15%.Based on the effectiveness of prevention,reducing the dosage of chlorpyrifos by 15%and combining it with Huifeng is the best choice for controlling corn borers in Shanxi region.However,considering the cost of efficiency enhancement,reducing the dosage of chlorpyrifos by 15%and combining it with Jianjian has a high cost-effectiveness.The prevention and control of corn borers in the Shanxi region must be tailored to local conditions and times,and based on thorough investigation and accurate prediction,it is possible to formulate the optimal prevention and control plan with targeted measures.It is necessary to achieve high efficiency in prevention and control,as well as to achieve the synergy and unity of reducing drugs,increasing production,and green quality,and promote the vigorous development of quality and efficiency oriented new agriculture in China.