Urbanization Drives Community Reorganization, Functional Filtering, and Pest Dominance in Tropical Termites

Abstract

Urbanization is expanding most rapidly in tropical regions, yet its impacts on termites, ecosystem engineers of major ecological and economic importance, remain poorly understood. We combined community surveys and morphological analyses across paired urban and forest habitats in island (Guadeloupe) and continental (Costa Rica) systems to assess how urbanization reshapes termite assemblages and functional traits. Across 20 sites and 1000 quadrats, we quantified community composition, environmental associations, and functional morphology. Forest assemblages showed greater species nestedness, indicative of non-random species loss linked to fragmentation, whereas urban assemblages exhibited higher turnover, reflecting species replacement in heterogeneous, human-modified habitats. Soil-feeding termites were significantly less frequent in Guadeloupean cities, associated with elevated temperatures, reduced soil organic carbon, and lower canopy cover. In Costa Rica, the opportunistic pest Nasutitermes ephratae occurred nearly twice as often in urban areas, which is concerning given its similarity to Nasutitermes corniger, an already established pest. This highlights cities as potential bridgeheads for emerging invasions and pathways for introduction via trade. Morphological analyses revealed habitat-associated trait shifts in opportunistic species: urban Nasutitermes populations exhibited reduced body size traits, including pronotum width, femur length, and mandibular indices, consistent with the temperature-size rule and urban heat island effects. These findings indicate that tropical urbanization does not simply reduce termite diversity but reorganizes communities, favors pest-prone species, and induces functional trait shifts that may enhance invasion risk. By integrating community and morphological data across contrasting biogeographic contexts, this study highlights the need to incorporate biodiversity conservation, evolutionary responses, and biosecurity considerations into urban ecology.