Pupal emergence pattern in cactophilic Drosophila and the effect of host plants

Effects of three different host plants on two sex life table parameters of the fall armyworm Spodoptera frugiperda

The fall armyworm Spodoptera frugiperda (Lepidoptera: Noctuidae) is a major phytophagous pest that invaded China in late 2018, posing a serious threat to local agricultural production. Therefore, we investigated the effects of maize, soybean, and sweet potato on the growth, development, and reproduction of S. frugiperda under laboratory conditions. The developmental period of the egg-larval stage was significantly longer when S. frugiperda fed on sweet potato (28.94 days) compared to maize (16.19 days) and soybean (17.82 days). Sweet potato feeding significantly prolonged the pupal period, but this effect was not observed in the adult stage. Spodoptera frugiperda larvae fed on sweet potato had the lowest pupal weight (116.18 mg) and pupation rate (68.19%). The mean fecundity of females significantly differed among the plants, with egg production being highest for insects fed on maize (996.17 eggs) and lowest for those fed on sweet potato (319.28 eggs). Spodoptera frugiperda fed on sweet potato exhibited the smallest net reproductive rate (47.892), lowest intrinsic rate of increase (0.083 day-1), lowest finite rate of increase (1.086 day-1), and longest mean generation time (46.806 days). Overall, S. frugiperda can survive and complete its entire life cycle on all three host plants.

Oviposition Preference and Age-Stage, Two-Sex Life Table Analysis of Spodoptera frugiperda (Lepidoptera: Noctuidae) on Different Maize Varieties

Host plants play an important role in the growth, development, and reproduction of insects. However, only a few studies have reported the effects of maize varieties on the growth and reproduction of S. frugiperda. In this study, a free-choice test was used to evaluate the oviposition preferences of female adults on ten common maize varieties and ten special maize varieties. The population fitness of S. frugiperda on six different maize varieties was also examined using the age-stage, two-sex life table method. The results showed that S. frugiperda oviposited and completed its life cycle across all maize cultivars. Moreover, the S. frugiperda females exhibited a significantly higher oviposition preference on the special maize varieties than on the common maize varieties. The highest number of eggs and egg masses occurred on Baitiannuo and the lowest on Zhengdan 958. The egg + larval stage, preadult, pupal stage, adult, APOP, TPOP, and total longevity of S. frugiperda were significantly shorter on the special maize varieties than on the common maize varieties. The fecundity, oviposition days, pupal weight, and hatching rate of S. frugiperda were significantly higher on the special maize varieties than on the common maize varieties. Specifically, S. frugiperda had the highest fecundity, female, and male pupal weight on Baitiannuo. Moreover, the net reproductive rate (R₀), intrinsic rate of increase (r), and finite rate of increase (λ) of S. frugiperda were the greatest on Baitiannuo, whereas the shortest mean generation time (T) occurred on Zaocuiwang. The lowest R₀, r, and λ, and longest T occurred on Zhengdan 958, suggesting that Zhengdan 958 is a non-preferred host plant compared to the other tested maize varieties. The findings of this study can provide a reference for the rational planting of maize and provide basic scientific information for the management of S. frugiperda.