夏玉米不同生育时期草地贪夜蛾防治指标研究

Studies on the control index of Spodoptera frugiperda at different growth stages of summer maize

【目的】明确玉米不同生育时期草地贪夜蛾的防治指标,为草地贪夜蛾的精准防控提供理论依据。【方法】采用田间人工接虫和模拟防治方法,以河南省主栽玉米品种郑单958为材料,分别在玉米小喇叭口期、大喇叭口期和吐丝期接入草地贪夜蛾3龄初期幼虫,设0、1、2和3头·株-14个处理,重复3次,接虫后第7天喷药杀灭幼虫,待受害叶片完全长出后调查玉米叶面积,至玉米收获期调查株高、穗长、穗直径、百粒质量、穗粒质量、产量等指标,计算草地贪夜蛾为害造成的产量损失率及防治指标。【结果】玉米受害叶面积、叶面积损失率和产量损失率均随幼虫密度提高而加大,2021年夏玉米3个生育时期平均每头幼虫造成的产量损失率分别为7.54%、4.99%和3.96%,2022年分别为7.33%、5.34%和4.59%。产量水平7500~12000 kg·hm^(-2)条件下,化学防治为主时,夏玉米小喇叭口期草地贪夜蛾的防治指标为11.1~17.6头·百株^(-1),大喇叭口期为15.9~25.4头·百株^(-1),吐丝期为21.9~35.0头·百株^(-1);生物防治为主时,3个生育时期草地贪夜蛾的防治指标分别为39.0~62.5、56.2~90.0和78.1~125.0头·百株^(-1)。【结论】明确了夏玉米不同生育时期不同产量水平田对草地贪夜蛾实施不同防治策略时的防治指标,可作为河南省夏玉米田草地贪夜蛾实时防控和精准施药的依据。

【Objective】To clarify the control index of Spodoptera frugiperda at different growth stages of maize,and provide theoretical basis for accurate control of Spodoptera frugiperda.【Method】Using the Zhengdan 958 of main maize variety in Henan Province as the material and the field artificial in-sect-catching and simulated control as methods,the early third instar larvae of Spodoptera frugiperda were introduced on maize plant at the early whorl stage,late whorl stage and silk stage,respectively.Each plant was separately treated with 0,1,2 and 3 larvae,and repeated three times.On the 7th day after inoculation,the larvae were killed by spraying insecticide.When the damaged leaves grew out completely,the area of maize leaves was investigated.Furthermore,the plant height,ear length,ear diameter,100 grain mass,ear grain quality and yield were surveyed at the harvest stage to calculate the yield loss rate and control index caused by Spodoptera frugiperda infestation.【Result】The damaged leaf area,leaf area loss rate and yield loss rate of maize increased with the increase of larval density.The average yield loss rate per larva in the three growth stages of maize in 2021 was 7.54%,4.99%and 3.96%,and that in 2022 was 7.33%,5.34%and 4.59%respectively.Under the yield level of 7500-12000 kg·hm^(-2),the control indexes of Spodoptera frugiperda were 11.1-17.6 larvae per 100 plants in early whorl stage,15.9-25.4 larvae in late whorl stage,and 21.9-35.0 larvae in silk stage for chemical control.When applying biological control,the control indexes of Spodoptera frugiperda were 39.0-62.5,56.2-90.0 and 78.1-125.0 larvae per 100 plants,respectively.【Conclusion】The control indexes of different control strategies for Spodoptera frugiperda in summer maize fields of differ-ent growth stages and different yield levels were determined,which can be used as the basis for real-time and precise application of insecticide to control Spodoptera frugiperda in summer maize fields of Henan Province.