Effects of different maize varieties on the growth and development of Spodoptera frugiperda and the parasitization of Microplitis pallidipes

To investigate the effects of feeding on different maize varieties on the growth, development, and reproduction of Spodoptera frugiperda, and on the parasitism of Microplitis pallidipes to S. frugiperda, effects of feeding on three varieties of fresh maize (Shenketiannuo 99, Shenkenuo 602, Shengketian 811), a common maize variety (Zhengdan 958) and artificial diet on the developmental duration, egg number, hatchability, and adult longevity of S. frugiperda were assessed. The indicators such as parasitism rate, cocoon and bee emergence rates of M. pallidipes to S. frugiperda feeding on different varieties of corn were statistically analyzed. The findings indicated that the number of eggs laid, the adult longevity, and the survival rate and developmental duration of S. frugiperda larvae were significantly influenced by a diet consisting of various corn varieties and artificial diet (P < 0.05). Generally, S. frugiperda feeding on fresh corn of 3 varieties exhibited a greater egg-laying capacity, an increased survival rate of larvae, and a reduced development duration. Among them, the adult S. frugiperda that feeding on Shenshennuo 602 had the largest number of eggs (1 420.78), the highest larval survival rate (82.33%), and the shortest larval development period (15.77 days). There were significant differences observed in the parasitism rate and cocoon emergence rate of M. pallidipes to S. frugiperda larvae feeding on different maize varieties and artificial diet (P < 0.05). Specifically, the parasitism rate of M. pallidipes to S. frugiperda feeding on common corn (64.18%) was higher than that of three fresh corn varieties (48.78%~54.75%), and the parasitism rate of M. pallidipes to S. frugiperda feeding on artificial diet was the lowest (39.41%). The higher cocoon emergence rate of M. pallidipes was found in the parasitized S. frugiperda feeding on artificial diet and common corn (74.80% and 72.53%), while it was lower in those feeding on fresh corn (48.39%~55.49%). These results indicated S. frugiperda feeding on fresh corn had better growth and reproduction ability. The parasitic effect of M. pallidipes on S. frugiperda feeding on common corn was better than those S. frugiperda larvae feeding on fresh corn. Therefore, when the parasitoid M. pallidipes is used to control S. frugiperda in the fresh corn planting area, the release quantity or release times of the parasitoid should be appropriately increased to ensure the control effect.