Vector Traits Shape Disease Persistence: A Predator-Prey Approach to Dengue.

Dengue continues to pose a major global threat, infecting nearly 390 million people annually. Recognizing the importance of studying vector biology and therein vector competence ( v c ), recent research focuses on mosquito parameters to inform transmission modeling and vector control strategies. This study models relationship between Aedes vectors and dengue pathogens, highlighting v c as a key driver of within-vector infection dynamics and endemic persistence. Using a predator-prey framework, we show that endemic conditions emerge naturally from the biological interplay between vector's strategies and pethogen pressure. We prove global stability of such conditions and determine thresholds of v c for three types of functional responses ( v c q ∗ , q = 0 , 1 , 2 ). Our results reveal that under tropical and subtropical environmental pressures, the innate immune system of vectors cannot offset high v c during endemic outbreaks, highlighting a fundamental biological trade-off: vectors can evolve increased transmission potential but cannot enhance immune capacity. This constraint defines the limits of their evolutionary response to pathogen-driven selection and drives instability in disease transmission dynamics.