Integrated discrete epidemiological simulation model for the population dynamics of Diaphorina citri in relation to the crop cycle

• DOI: https://doi.org/10.22533/at.ed.82081626140115

• Palavras-chave: Vector dynamics, Discrete epidemiological model, Huanglongbing (HLB)

• Keywords: Vector dynamics, Discrete epidemiological model, Huanglongbing (HLB)

• Abstract:

  Huanglongbing (HLB), associated with Candidatus Liberibacter asiaticus and transmitted by Diaphorina citri, is the main phytosanitary threat to citrus cultivation worldwide. The population dynamics of the vector are a determining factor in the persistence and spread of the disease; however, most of the available epidemiological models are based on continuous formulations that do not explicitly incorporate the discrete nature of the crop's phenological cycle. In this study, a discrete-time structured epidemiological model was developed that integrates the ontogenetic dynamics of eggs, nymphs, and adults with periodic environmental modulation, using a matrix-based population projection approach. The system was formulated using weekly difference equations and parameterized with experimentally reported biological values. The annual simulation (52 weeks) showed environmentally forced nonlinear dynamics, characterized by an initial phase of exponential expansion, followed by contraction associated with reduced effective fecundity and subsequent recovery under favorable thermal conditions. The maximum egg population reached 2.1 × 10⁶ individuals in week 15, while the adult compartment showed greater relative stability, maintaining structural persistence during subcritical phases. Spectral analysis indicated that the dynamic regime depends on the effective fertility value βₜ, with supercritical behavior when βₜ > 30 eggs·adult⁻¹·week⁻¹ and contractive behavior when βₜ < 5. The temporal lag between stages allowed the identification of critical intervention windows associated with the transition between immature and adult states. The explicit incorporation of the phenological cycle into a discrete framework provides a formal basis for integrating plant–vector transmission and evaluating management strategies under climate variability.