Feeding preference and adaptability of Spodoptera frugiperda (Lepidoptera: Noctuidae) on different wheat cultivars in relation to leaf biochemical contents#br#.
Aim: This study aims to determine the feeding preference and adaptability of the fall armyworm (FAW), Spodoptera frugiperda, on different wheat cultivars collected from the Huang-Huai-Hai wheat growing areas in North China, to explore the relationship between insect pest damage and wheat cultivars, and to clarify the resistance levels of different wheat cultivars to FAW, so as to provide a theoretical basis for the arrangement of insect resistant cultivars and integrated pest management in wheat fields. Methods: The feeding preference of the 1st and 3rd instar larvae of FAW to 15 wheat cultivars was compared. Four wheat cultivars with high feeding preference and two wheat cultivars with low feeding preference for the 1st and 3rd instar larvae of FAW were screened out, the contents of biochemical components (total protein, soluble sugar, total phenol and tannin) in leaves of these six wheat cultivars were determined, the relationship between the feeding preference of the larvae and the contents of biochemical components in leaves of these six wheat cultivars was clarified by Pearson correlation analysis, and the adaptability of FAW on the six wheat cultivars was observed. Results: The results revealed that the 1st and 3rd instar larvae of FAW preferred to feeding on Huaimai 46, Huaimai 33, KOK1679 and Tongmai 6, but not on Luyuan 502 or Yannong 21. The feeding preference of the 1st and 3rd instar larvae to leaves of different wheat cultivars was positively correlated with the total protein content and the soluble sugar content in wheat leaves, but negatively correlated with the total phenol content and the tannin content. The development of FAW was significantly different on leaves of different wheat cultivars, with the highest host suitability index and the shortest larval duration on Tongmai 6, and with the longest larval duration on Yannong 21. Conclusion: The FAW showed different adaptability to different wheat cultivars, and Yannong 21 showed higher resistance to this insect pest. The FAW larvae prefer wheat leaves with higher contents of total protein and soluble sugar, while the feeding can be inhibited by high contents of total phenol and tannin in wheat leaves. It is speculated that the difference of resistance levels of different wheat cultivars to FAW is resulted from the coordination of non-preference and antibiosis in wheat by the metabolism of nutrients and secondary substances.