Population Dynamics And Prevention And Control Techniques Of The Rice Leaf Roller In Shanghai Farms

Cnaphalocrocis medinalis Guenee is one of the main migratory pests in rice production in the rice area of the Yangtze River Basin,which poses a great threat to the high quality and high yield of rice in Jiangsu.Shanghai Farm is located in Dafeng District,Jiangsu Province,with more than 4,700 hectares of rice cultivation area.In recent years,C.medinalishas a large area and a large amount of occurrence,and the generation overlap is serious,which brings some difficulties to the comprehensive prevention and control of the field.In order to effectively prevent and control the occurrence and damage of C.medinalis,accurate forecast is the basis.Therefore,based on the field moth catching data of 29 sites in three areas in 2014-2019 for six consecutive years,this paper combines the field moth catching with the amount of moth under the lamp,field moth checking and egg checking,analyzes the dynamic law of the pest population by using DPS and other data statistical software,and makes induction and analysis,so as to comprehensively and systematically grasp the occurrence dynamics of C.medinalis population in this field,and provide basis for effective prevention and control of its harm in production.At the same time,a variety of insecticides used and to be used in recent years to control C.medinalis were screened,and the comprehensive control measures were put forward.The main results are as follows:The results of population dynamics analysis showed that C.medinalis had 3-4generations in one year,four(2)generations of adults began to move in,and the occurrence degree of moth population was light;In the early stage of the five(3)dynasties,the migration of adults was less,while in the later stage,the number of immigrants increased;The six(4)generations are relatively complex:in general years(2016-2019),the six(4)generations are dominated by the migration of local sources transformed into adults.In special years(2014-2015),the first six(4)generations were overlapped with the local ones,and the moth population was large.Specifically:In the three years of 2014,2015,and 2018,there were a large number of moths in the early stage of six(4)generations and the number of moths per day reached about 120 per 66.7 m2.The three years of 2016,2017,and 2019,there were a large number of moths in the late stage of five(3)generations and the number of moths per day reached 58.7-97.3 per 66.7 m2.From the first ten days of August to the first ten days of September,the population number of C.medinalis was the largest in Shanghai farm,especially in the middle and last ten days of August to the first ten days of September.The results showed that monitoring the occurrence and damage of the five(3)and six(4)generations of C.medinalis was the most important work in plant protection.Through the efficacy tests of six chemical insecticides and one biological insecticide on the larvae of C.medinalis of 1-2 and 3-4 instars respectively,and the correction control effect of different insecticides at the same time and different time after the same insecticide was comprehensively evaluated.The results showed that(1)After the control of C.medinalis of 1-2 instars,except for 30ml of 5%methylaminoabamectin benzoate microemulsion,which correction control effect of the chemical insecticide was the best effect 3 days after applying insecticides while the other six insecticides were the best after 7 days.After 3-4 instars control of C.medinalis,all the insecticides had the best control effect in 3 days.(2)The correction control effect of each insecticides in 1-2 instars C.medinalis is better than that in 3-4 instars control.Taking 15 ml of 16%methotrexate suspension concentrate as an example,the control effect of C.medinalis of 1-2 instars was 85.88%after 7 days,while the control effect of C.medinalis of 3-4 instars was only 17.02%after 7 days.(3)12 ml of 15%indoxacarb suspension concentrate was the best one among 7 kinds of insecticides,and the correction control effect was 88.27%in 7 days after applying insecticides.30 ml of 6%spinetoram emulsifiable concentrate was used as a biological insecticide to control the 1-2 instars C.medinalisafter 7days,which was 87.40%,next to 12 ml of 15%indoxacarb suspension concentrate and superior to the other five insecticides(87.17%,85.88%,78.67%,78.27%,67.78%in turn from high to low 7 days after applying insecticides).Therefore,this paper proposes that the best control instar of C.medinalis should be closely linked,high-efficiency insecticides should be selected accurately and applied scientifically and reasonably,so as to ensure the high-efficiency control of C medinalis and provide guarantee for the high yield and quality of rice in this field.