Wheat-Bran-Based Artificial Diet for Mass Culturing of the Fall Armyworm, Spodoptera frugiperda Smith (Lepidoptera: Noctuidae)

Abstract

Spodoptera frugiperda Smith (fall armyworm (FAW)) has invaded many countries in Africa and Asia in recent years, considerably restricting global agricultural production. In this study, we assessed the rearing performance of four artificial diets (D1: an artificial FAW diet based on wheat bran and soybean, maize, and yeast powders; D2: an artificial diet developed for Helicoverpa armigera (Hübner), based on wheat bran and soybean and yeast powders; D3: an artificial diet based on soybean powder; D4: an artificial diet based on wheat bran) for FAWs. We designed D4 based on a traditional diet (D2) but substituted the wheat bran for soybean and yeast powders. At 25 ± 1 °C, 75% ± 5% RH, and a 16:8 h L:D photoperiod, the larval stage of FAWs fed on D4 lasted 15.88 d, the pupal stage lasted 9.48 d, the pupal mass was 270.45 mg, the number of eggs deposited was 1364.78, and the mating rate was 89.53%. Most biological indicators of the larvae that were fed D4 were basically consistent with those of the larvae fed on the traditional diet (D2), but the intrinsic rate of increase (r), finite rate of increase (λ), and net reproduction rate (R0) of the D4 FAWs were lower than those of the D2 FAWs. The flight capacity (flight distance, duration, and velocity were 19.73 km, 6.91 h, and 2.90 km/h, respectively) of the D4 FAWs was comparable to that of the FAWs fed a traditional diet and maize leaves. Compared with the three other formulas, the cost of using D4 was lower by 26.42% on average. These results show that using cheap wheat bran instead of soybean flour and yeast powder as the basic material for an artificial diet for FAWs is feasible, which will substantially reduce rearing costs and promote the development of new controlling measures for FAWs. In addition, this study also has a reference value for reducing the cost of artificial diets for other insects.