Climatic and host‐plant drivers of continental‐scale Miridae diversity: Integrating generalized linear modelling with local spatial association analyses

Abstract Identifying the mechanisms that structure large‐scale insect diversity is central to ecological theory. Herbivorous insects are expected to respond both to direct climatic constraints and to bottom‐up regulation mediated through host‐plant diversity, yet the relative importance of these pathways at continental scales remains unresolved. This study evaluates drivers of species richness in Miridae (Hemiptera: Heteroptera) across the Nearctic region using negative binomial generalized linear models integrated with global and local spatial autocorrelation analyses. Climatic predictors representing energy availability, water balance, atmospheric moisture and winter thermal minima were assessed alongside host‐plant richness to distinguish direct climatic effects from trophically mediated influences. Miridae richness exhibited pronounced spatial heterogeneity, with diversity peaks concentrated in southern and southwestern regions. Host‐plant richness was a strong positive predictor of mirid diversity, supporting bottom‐up diversification hypotheses. However, climatic models consistently outperformed biotic‐only models. Atmospheric moisture exerted a strong negative association with richness, whereas potential evapotranspiration, annual precipitation and minimum temperature of the coldest month showed positive effects. Inclusion of winter thermal minima significantly improved model fit, underscoring the importance of cold limitation in structuring insect distributions. Sequential modelling indicated that climate influences mirid richness both directly and indirectly through host‐plant diversity. Residual spatial autocorrelation was eliminated in the best‐supported model, demonstrating that contemporary climatic gradients and host availability collectively account for the dominant geographic structure of Miridae diversity. These findings indicate that continental‐scale patterns of herbivorous insect richness arise from a hierarchical interaction between abiotic constraints and trophic opportunity, with climate establishing the bounds within which bottom‐up processes operate. The results extend climate‐richness theory to a hyperdiverse phytophagous insect clade and provide a mechanistic framework for anticipating insect responses to ongoing environmental change.