The Potential of Using Different Legume Species in a Push–Pull Approach to Manage Spodoptera frugiperda in Maize in China

Abstract

Fall armyworm (FAW), Spodoptera frugiperda (Smith), a notorious pest native to the tropical and subtropical Americas, has recently invaded China, causing substantial damage to crops, particularly maize. The push–pull strategy has been reported to be an effective prevention measure for FAW in Africa, with maize–soybean intercropping significantly reducing FAW infestation. To assess the potential of legume hosts as ‘push’ or ‘pull’ plants to control FAW in maize, we employed life table analysis and indoor cage tests to investigate the offspring performance, feeding and oviposition preference of FAW on five selected legume species, namely mung bean (Vigna radiata L.), soybean (Glycine max L.), kidney bean (Phaseolus vulgaris L.), red bean (Vigna angularis Willd.) and cowpea (Vigna unguiculata L. Walp), with maize (Zea mays L.) as a control. Mung bean and cowpea were subsequently selected as repellent and attractant plant, respectively, to study FAW infestation levels in maize in the field. The results showed that maize was the most suitable host plant for FAW, as indicated by its shortest developmental duration and highest pupal weight. However, among all the tested legume species, cowpea was the best host for FAW, with shorter larval, pre-adult and adult durations than on the leaves of the other legumes. Moreover, the feeding and oviposition preference tests revealed that FAW had a strong preference for maize and cowpea, but strongly rejected mung bean. Compared with that in the maize monoculture group, the total number of eggs laid in the maize–mung group decreased by 67.25%, whereas that in the maize–cowpea group significantly increased by 2.04-fold in greenhouse tests. In the randomised block field experiment, the infestation of maize by FAW in the mung bean–cowpea system was significantly lower than that in the maize monoculture or in the system with maize surrounded only by cowpea. This study indicated that mung bean and cowpea are promising candidates as repellent plants (push) and attractant plants (pull), respectively, for intercropping with maize to reduce the damage caused by FAW.