Temperature and competition: drivers in the ecological dynamics of Aedes mosquitoes and dengue spread

Dengue is a mosquito-borne viral disease endemic to tropical regions, primarily transmitted by Aedes aegypti and Aedes albopictus. Climate-driven temperature changes are altering vector ecology and expanding the geographic range where both species coexist. However, the combined effects of temperature variability and interspecific interactions, particularly the highly competitive larval stage, on mosquito population dynamics and dengue transmission remain poorly understood.

We developed a deterministic model incorporating temperature-dependent parameters to analyze vector interactions across larval stage, coupled with a Susceptible-Exposed-Infected-Recovered (SEIR) framework for human infection dynamics. We evaluated species invasion capability, population dynamics, and transmission patterns through invasion and coexistence analyses, as well as infection peak assessment. The basic reproductive number ( $R_0$ ) was derived analytically using the next-generation matrix (NGM) method, while the effective reproductive number ( $R_t$ ) was computed from numerical simulations to capture dynamic effects of larval competition.

The invasion analysis showed that larval competition was the central determinant of species outcomes. Under temperature-independent conditions, Aedes albopictus could invade only when the larval pressure exerted by Aedes aegypti ( ${\omega }_{\mathrm{ae}}$ ) was relatively low, while intermediate values produced neutral dynamics, and higher values prevented invasion. Incorporating temperature dependence broadened the parameter space in which invasion was possible, indicating that thermal variation enhances the invasion potential of Aedes albopictus. Coexistence patterns reflected this shift; temperature-independent simulations favored Aedes aegypti dominance, whereas temperature-dependent scenarios led to nearly balanced coexistence between the species. Dengue transmission patterns qualitatively followed these ecological dynamics. Temperature-independent simulations produced smaller peaks in human dengue cases, while temperature-dependent scenarios yielded a larger number of cases. Stronger competition from Aedes albopictus lowered epidemic intensity. The basic reproductive number ( $R_0$ ) was indirectly modulated by larval competition through its effects on adult mosquito abundance, while the effective reproductive number ( $R_t$ ) remained higher in temperature-independent settings and decreased substantially under stronger larval competition in temperature-dependent simulations. The purpose of the transmission component of the model is to illustrate how changes in larval competition propagate through the transmission framework, rather than to provide quantitatively validated epidemiological estimates.

Temperature significantly influences competitive interactions and dengue transmission dynamics between Ae. aegypti and Ae. albopictus. Temperature-dependent conditions enhance Ae. albopictus invasion and promote coexistence, while Ae. aegypti drives higher infection peaks under favorable thermal conditions. Increased Ae. albopictus competition lowers transmission, particularly in temperature-dependent scenarios; however, situations where both vectors exhibit similar abundances represent the most concerning context. These findings underscore the importance of integrating temperature effects and interspecific competition into vector control strategies in regions such as Colombia, where both species coexist, to effectively mitigate dengue transmission under varying climatic conditions.