Biological reinvasion of Cochliomyia hominivorax (Diptera: Calliphoridae) in Mexico: impacts and risks under different climate change scenarios.

The New World screwworm, Cochliomyia hominivorax (Diptera: Calliphoridae), is an obligate parasitic fly that causes severe myiasis in livestock, wildlife, and humans, generating substantial economic and public health impacts. Following its historical eradication from North and Central America through sterile insect technique (SIT) programs, recent outbreaks in Central America and southern Mexico indicate ongoing biological reinvasion. We evaluated current and future environmental suitability for C. hominivorax using ecological niche modeling (Maximum Entropy [MaxEnt]) calibrated with 1,972 occurrence records derived from 10,204 outbreak reports across Mexico and Central America. Models were developed using WorldClim bioclimatic variables under current climatic conditions (1970-2000) and future climate scenarios (Shared Socioeconomic Pathways [SSPs]: SSP1-2.6 and SSP5-8.5 for 2050). Suitable environments currently encompass most of Central America and 27 of 32 Mexican states, with highest suitability concentrated in southeastern Mexico. Future projections indicated expansion and intensification of highly suitable areas, particularly in the Yucatán Peninsula, Chiapas, and Tabasco. Spatial analysis of 238 human myiasis cases reported in Mexico during 2025-2026 revealed significant aggregation within highly suitable areas predicted by the models (χ2 = 179.3, P < 0.001). These findings suggest that environmental suitability is spatially associated with the current reemergence of C. hominivorax and may facilitate further expansion under climate change. Our results highlight the need for strengthened surveillance, regional biosecurity strategies, and coordinated One Health interventions to prevent large-scale reinfestation across Mesoamerica.