The potential of using different legume species in a push-pull approach to manage Spodoptera frugiperda in maize in China

<p>Fall armyworm (<em>Spodoptera frugiperda</em>)<em> </em>is a notorious pest on crops, especially on maize. The push-pull strategy based on the intercropping system has been reported to effectively reduce the damage of <em>S. frugiperda</em>. However, the suitable mode for <em>S. frugiperda</em> management in maize-based intercropping systems in China has not been reported thoroughly. In this study, the adaptability, feeding, and oviposition preferences of <em>S. frugiperda</em> on maize (<em>Zea mays</em> L.), mung bean (<em>Vigna radiata</em> L.), soybean (<em>Glycine max</em> L.), kidney bean (<em>Phaseolus vulgaris</em> L.), red bean (<em>Vigna angularis</em> Willd.) and cowpea (<em>Vigna unguiculata </em>L. Walp), were firstly compared through lift table analysis and indoor cage tests. Subsequently, based on the results from the laboratory tests, mung bean –cowpea was selected as the push-pull system for <em>S. frugiperda</em> occurrence studied in the field. Results showed that maize is the most suitable host for <em>S. frugiperda</em>, as indicated by the shortest developmental duration and the highest pupal weight. However, among all the tested bean plants, the cowpea is the best for <em>S. frugiperda</em>, on which the larval duration, pre-adults, and adult durations were significantly shorter than others. Meanwhile, the feeding and oviposition preference tests revealed that <em>S. frugiperda</em> had a strong preference for maize and cowpea, while the opposite was true for mung bean. Compared to maize monoculture, the number of eggs of <em>S. frugiperda</em> laid in maize-mung decreased by 67.25%, and that in maize-cowpea significantly increased to 2.04 times. In a randomized block experiment in the field, it was found the incidence of maize in the mung bean-cowpea system was significantly lower than that of maize monocropping and maize only surrounded by cowpea. This study indicated that mung bean and cowpea are promising candidates as a repellent plant (push) and attractant plants (pull) to be intercropped with maize using the push-pull strategy to lessen the damage caused by <em>S. frugiperda</em> in maize-based intercropping systems.</p>