Temperature and Host Plant Impacts on the Development of Spodoptera litura (Fabricius) (Lepidoptera: Noctuidae): Linear and Nonlinear Modeling

SIMPLE SUMMARY: The tobacco cutworm, Spodoptera litura (Fabricius) (Lepidoptera: Noctuidae), is a highly polyphagous and destructive insect pest, damaging a wide range of vegetables and field crops in Korea. Timely management is very important, as delays can lead to considerable economic losses. For timely management, the development of precise forecasting models is important in pest management. In this study, we estimated the temperature-based thermal requirements of S. litura with linear and nonlinear models on host plants to develop models to foresee the spring emergence and population dynamics of S. litura. We found a significant impact of temperature and host plant on the development of S. litura. Development was found to be inversely proportionate to temperature, despite no development at extreme temperatures. Based on the estimated thermal requirements, we developed a forecasting model, and this predicated the spring emergence of S. litura in May–June. Thus, the continuous observation of S. litura in crop fields is required in order to prepare more advanced administration measures against S. litura. ABSTRACT: The tobacco cutworm, Spodoptera litura (Fabricius) (Lepidoptera: Noctuidae), is one of the most serious pests in field crops, vegetables, and ornamentals. Temperatures (15, 20, 25, 27, 30, 35, and 40 °C), host plants (soybean (Glycine max (L.)), maize (Zea mays L.), groundnut (Arachis hypogaea L.) and azuki bean (Vigna angularis (Willd.) Ohwi & H. Ohashi,), and the artificial diet-dependent developmental parameters and survival of S. litura were examined in this study. Stage-specific parameters such as threshold development temperature (LDT) and thermal constant (K) (Degree day (DD)) were determined by linear and nonlinear models (Sharpe–Schoolfield–Ikemoto), respectively. The total developmental time (egg–adult) decreased with increasing temperature on host plants and with an artificial diet. The total immature developmental time varied from 106.29, 107.57, 130.40, 111.82, and 103.66 days at 15 °C to 22.47, 21.25, 25.31, 18.30, and 22.50 days at 35 °C on soybean, maize, groundnut, azuki bean, and artificial diet, respectively. The LDT for the total immature completion was 7.50, 9.48, 11.44, 12.32, and 7.95 °C on soybean, maize, groundnut, azuki bean, and artificial diet, respectively. The K for the total immature completion was 587.88, 536.84, 517.45, 419.44, and 586.95 DD on soybean, maize, groundnut, azuki bean, and artificial diet, respectively. Temperature and host plant interaction also influenced the longevity and survival of adults. The findings of this study can be used to predict the number of generations, spring emergence, and population dynamics of S. litura. The nutrient content analysis of the host plants is discussed in terms of the developmental patterns of S. litura.