Temperature-dependent development and reproduction models of rice brown planthopper, Nilaparvarta lugens (Stål)

Nilaparvata lugens (Stål) is a serious sucking insect of rice in the world. Temperature significantly alters insect growth, development and reproduction parameters. The present study determines the required thermal constants and their effect on the life table parameters of N. lugens, focusing on the impact of temperature. Temperature-dependent linear and non-linear developmental rates, stage-specific mortality and fecundity model functions were fitted at five constant temperature regimes (18–34°C). The Insect Life Cycle Modelling (ILCYM) software was used to fit non-linear equations and to establish an overall phenology model to simulate life table parameters for each constant temperature. The lower temperature development thresholds (LTT) and thermal constants (k) were identified for each developmental stage from egg to adult and estimated from a linear function. At constant temperatures between 18 and 34°C, the developmental duration of eggs and nymphs shortens with higher temperatures, with optimal development observed between 22 and 30°C. Similarly, the maximum fecundity was observed at 26°C, and life table parameters were calculated through stochastic simulations. Life table parameters indicated higher intrinsic growth rates (r_m) and net reproductive rate (R₀) at 26 and 30°C. Additionally, the models were validated with observed and simulated values. Life table parameters, mortality and developmental time were similar to predicted values. The study's findings will help with risk assessment in the context of climate change scenarios for this pest of rice. Further, this study will help devise monitoring strategies against this pest and develop a decision support system for implementation in rice-integrated pest management.