Response of Spodoptera frugiperda (Lepidoptera: Noctuidae) to salt-stressed maize plants

Salt-stressed maize is an economically important crop in many arid and semi-arid regions of the world where soil salinization is most common, and the invasive fall armyworm (FAW) Spodoptera frugiperda threatens global maize production. It thus poses a puzzle of whether FAW populations feeding on salt-stressed maize plants are becoming more or less invasive. Here, we evaluated the FAW response to salt-stressed maize plants by examining effects of salt-stressed maize plants on FAW survival, development and fecundity. We found a longer larval development time (salt-stressed, 12.9 +/- 0.8 d; non-stressed, 11.3 +/- 0.4 d), but unaffected survival rate and pupal mass accumulation in FAW feeding on salt-stressed maize plants. Moreover, the lifetime egg production of FAW females feeding on salt-stressed maize plants (633.5 +/- 62.7 eggs) was reduced by nearly half compared with those feeding on non-stressed maize plants (1255.9 +/- 70.3 eggs). Overall, FAW showed a negative response to salt-stressed maize plants. Due to limited population increase potential, FAW populations feeding on salt-stressed maize plants should pose less of a problem than ones feeding on non-stressed maize plants do. In practice, salt-stressed maize plants are quite common in arid and semi-arid regions where the relatively high-salinity groundwater is often used to irrigate maize plants, potentially limiting FAW population size. Thus, salt-stressed maize plants would contribute to practical applications of integrated pest management (IPM) strategies in controlling FAW.