Distribution characteristics of Spodoptera frugiperda (Lepidoptera: Noctuidae) winter populations in typical Mountain agricultural area of Southwest China

Abstract

Fall armyworm (FAW), Spodoptera frugiperda (Lepidoptera: Noctuidae) is one of the most damaging crop pests worldwide and has become a significant threat to the food security in many countries. The Lancang River (Mekong) valley and Nujiang River (Salween) valley, which are typical mountain agricultural areas located in the Hindu Kush-Himalayan (HKH) mountain range, are the key channels for the south to north migration of FAW in southwestern China. The purpose of this study was to analyze the population structure and distribution of FAW winter populations in the Lancang River and Nujiang River basins and relate these findings with respect to altitude, latitude, and mean monthly winter temperature in order to explore the spatial and temporal distribution characteristics of the winter population. Our results indicated that overwintering populations of FAW mainly appeared in winter cornfields with a few pupae found in summer cornfields near the middle and lower reaches of the Lancang River basin (south 26.04° N and below 1600 m) and the Nujiang River basin (south of 26.80° N and below 1500 m). Winter corn appeared to be a prerequisite for the occurrence of FAW in winter. The mean monthly temperature of the coldest month being greater than 10 °C is one critical factor determining where FAW populations will occur in winter. Some control options that could be used in these river basins include adjusting crop planting patterns and developing a large-scale non-host isolation band.