Field resistance and laboratory fitness of different maize varieties to Spodoptera frugiperda

Objective Spodoptera frugiperda is one of main pests damaging maize.It is the most economical and environmentally friendly strategy to control S. frugiperda by selecting and using resistant maize variety. Method In this study，the field resistance of 47 maize varieties to S. frugiperda was evaluated by leaf damage level and ear damage level under natural infection in the field；and the laboratory fitness of S. frugiperda fed on 4 maize varieties which field resistance varied greatly was detected；finally，biochemical substances content of these maize leave were determined and their correlation with leaf damage index and feeding fitness was analyzed. Result The results showed that the resistance of 47 maize varieties to S. frugiperda was different between seedling stage and earing stage.At the seedling stage，there were also 39 sensitive varieties and 7 highly sensitive varieties and only Jingke 968 reached the medium resistance level.At the ear stage，8 varieties showed high resistance，5 varieties reached the resistance standard，13 varieties were moderately resistant，7 varieties were sensitive，and 14 varieties were highly sensitive.The varieties with high resistance were Wanxiantian 159，Meiyushuangtiannuo 502，Guitian 571，Ganketian 9，Baimuda，Guitian 570，Zhengtian 68，Jingheng 18-1.The host suitability index of S. frugiperda fed on 4 maize varieties ranking from high to low were Ruiyu 926，Ganketian 8，Jingke 968 and Shuangcui 270，and host suitability index were 9.57，7.12，6.40，and 6.13，respectively.The leaf damage index in the field was positively correlated with reducing sugar content of maize leave（R=0.940，P=0.030），and the host suitability index was negatively correlated with tannin and total alkaloid content（tannin：R=-0.910，P=0.045；total alkaloid：R=-0.926，P=0.037），it was also negatively correlated with amylose and total sugar content，but there was no significant difference. Conclusion One maize variety with medium resistance in seeding stage and 8 maize varieties with high ear resistance were screened.Due to the poor resistance of different maize varieties to S. frugiperda under natural conditions，other green control technologies should be developed to reduce damage of this pest.This study also proved that the indoor fitness was different from the field resistance results.At the same time，it was found that reducing sugar，tannin and total alkaloid may be involved in maize defense pests，which provided a research basis for further screening of insect-resistant metabolites.