Towards an energy budget based toxicokinetic-toxicodynamic model for insect-plant interactions

Insect-plant interactions are critical in ecological and agricultural systems, often resulting in significant economic losses due to herbivory. This study introduces a Dynamic Energy Budget (DEB) based toxicokinetic-toxicodynamic (TKTD) model for understanding and managing these interactions, focusing on the fall armyworm (Spodoptera frugiperda) and its impact on maize (Zea mays). Our objectives were to parameterize a DEB-TKTD model for S. frugiperda develop a simplified DEB model for maize and integrate these models to predict larval feeding rates and plant damage under varying conditions. Laboratory bioassays provided data for model calibration, involving different application rates of the insecticide tetraniliprole. The DEB-TKTD model effectively captured the feeding inhibition in larvae exposed to tetraniliprole. Simulations indicated that even low application rates could significantly reduce feeding activity in the laboratory, with smaller larvae being more susceptible. The plant model accurately described maize growth and dry matter partitioning, aligning well with empirical data. Integrated model simulations demonstrated that larval feeding damage increased with population density and temperature. The model also indicated that plant damage varied with the timing of insecticide application. These findings were consistent with field observations and highlighted the importance of optimizing application timing and understanding underlying mechanisms for effective pest management. In conclusion, while there is potential for further refinement, the current model provides a valuable tool for exploring management thresholds and application strategies to mitigate S. frugiperda infestations, thereby supporting sustainable agricultural practices.