<![CDATA[This study formulates and analyzes a three-dimensional plant-pest-predator model with logistic plant growth and nonlinear trophic interactions. The main objective is to investigate how pest conversion efficiency influences population persistence, equilibrium stability, and changes in long-term dynamics. The model is shown to preserve nonnegativity and boundedness of solutions, ensuring its biological feasibility. Several equilibrium states are identified, including the pest-free equilibrium, the predator-free equilibrium, and two possible coexistence equilibria. Local stability analysis reveals that the pest-free state is stable when the pest cannot invade the plant population, whereas the predator-free state may become stable when the pest persists but the predator cannot establish. The two coexistence equilibria exhibit different dynamical properties: the branch associated with the lower plant density is unstable, while the branch associated with the higher plant density can be locally asymptotically stable. Bifurcation analysis shows that variation in pest conversion efficiency generates multiple transcritical bifurcations connecting the pest-free, predator-free, and coexistence states. The stable coexistence equilibrium may subsequently lose stability through a Hopf bifurcation, leading to oscillatory population dynamics. Numerical simulations support the analytical findings and illustrate the transitions from pest extinction to predator-free persistence, stable coexistence, and oscillatory behavior. These results demonstrate that pest conversion efficiency plays a central role in determining predator invasion, coexistence stability, and the effectiveness of biological pest control.]]>
