Publication Type
Journal Article
Journal Name
Ecological Modelling
Publication Date
12-1-2026
Abstract
The biology and population dynamics of terrestrial arthropods are strongly influenced by environmental conditions, particularly temperature, but thermal responses alone do not determine whether a population can establish when development depends on host resources. Here, we extend an existing physiologically based risk-index framework by explicitly coupling stage-structured insect demography with host-resource dynamics and deriving the resulting population-level invasion threshold through the Next-Generation Matrix (NGM) approach. The formulation integrates temperature-dependent development, fecundity and mortality across egg, larval, pupal and adult stages with host-resource production and depletion, yielding the basic reproduction number (R0[jls-end-space/]) as a mechanistically interpretable risk index, where (Formula presented) >1 identifies conditions permitting population growth. We demonstrate the framework using Busseola fusca and Chilo partellus, two major maize stemborers in Malawi. The stage-structured formulation produced distinct species-specific invasion windows: (Formula presented) >1 occurred between 19.4–30.6 °C for B. fusca and 24.5–36.7 °C for C. partellus, with maximum reproductive potential at 25.9 °C and 31.2 °C, respectively. Global sensitivity analysis identified female oviposition, adult mortality, resource decay and resource production as dominant drivers of the population-level threshold. Spatial application reproduced contrasting geographic patterns, with broader reproductive potential for B. fusca across central and northern Malawi and a more restricted warm-lowland pattern for C. partellus. Independent larval observations were positively associated with predicted stage-transition success, with stronger agreement for B. fusca (Spearman ρ =0.60) than for C. partellus (ρ =0.30). The framework therefore provides a general route for translating stage-specific physiological traits and resource dependence into an NGM-based population invasion threshold that can support mechanistic pest risk assessment and early-warning applications.
Keywords
Climate-driven pest dynamics, Early warning systems, Maize stem borers, Ontogenetic thermal responses, Resource-based risk index, Thermal trait-based modelling
Recommended Citation
Agboka, K., Rossini, L., Sokame, B., Meltus, Q., Onditi, J., Azrag, A., & Abdel-Rahman, E. (2026). A trait-based thermal risk-index framework integrating stage-structured insect demography, host resources and the Next-Generation Matrix. Ecological Modelling, 522 https://doi.org/10.1016/j.ecolmodel.2026.111849
Creative Commons License
This work is licensed under a Creative Commons Attribution-NonCommercial-No Derivative Works 4.0 International License.