Degree days and demography of Spodoptera frugiperda (J. E. Smith) (Lepidoptera: Noctuidae) on maize at different temperatures

Abstract

The temperature has a direct effect on the activity of insect pests and their developmental rate. The increasing temperature could profoundly influence the population dynamics, life cycle, length of reproduction, fecundity, and longevity. In the present study, the impact of different temperatures (32, 33, 34, 35 and 36°C) on the degree days and population fitness of Spodoptera frugiperda (J. E. Smith) was evaluated under artificial conditions. The results showed that for S. frugiperda, an average of 690.38 degree days was required to complete the total life span. The total larval developmental time, pupal duration and adult longevity required 237.38, 184.47 and 228.10 degree days, respectively. The life history data of S. frugiperda were analysed by using TWOSEX-MSChart. An increase in temperature reduced the developmental time of S. frugiperda at age x and stage j. The highest reproductive value (vx) of S. frugiperda was obtained at 34°C (600 individuals per day) and was found to be reduced at a further increase in temperature of 35°C (260 individuals per day) and 36°C (120 individuals per day). These results signify the improved fitness of S. frugiperda with increasing temperature levels, and the degree days help to predict the development pattern of S. frugiperda based on heat accumulation.