Larval diet affects development and reproduction of East Asian strain of the fall armyworm, Spodoptera frugiperda

In December 11, 2018, the fall armyworm (FAW), Spodoptera frugiperda invaded China and has since impacted local maize, sorghum and other crops. Here, we draw on laboratory experiments to show how different host crops (i.e., maize, sorghum, wheat and rice) and artificial diet affect larval growth and adult reproduction of one local FAW strain. Larval diet affected development duration, pupation rate, survival and emergence rate of pupae, and S. frugiperda adult fecundity. FAW attained the slowest larval development (19.4 days) on sorghum and the fastest (14.1 days) on artificial diet, with larvae attaining 99.6% survival on the latter food item. On rice, FAW larvae attained survival rate of 0.4% and were unable to pupate successfully. Pupation rate and pupal survival varied substantially between artificial diet and live plantlets at different phenological stages. Pupal weight was the highest (0.26 g) on artificial diet and the lowest (0.14 g) on sorghum, while FAW females reached the highest fecundity (699.7 eggs/female) on 2-leaf stage maize. Egg hatching rate equaled 93.6% on 4- or 5-leaf stage maize and 36.6% on artificial diet. FAW intrinsic rate of natural increase and the finite rate of increase varied between larval diets, reflecting how young maize leaves are the most suitable diet. Our findings can help to refine laboratory rearing protocols, devise population forecasting models or guide the deployment of ‘area-wide’ integrated pest management (IPM) modules in FAW-invaded areas of China and other Asian countries.