Do broader thermal ecological niches and higher activity levels in exotic ants provide a competitive advantage over subtropical native ant species?

Ectotherms’ body temperatures are closely linked to the environment, yet thermal ecology research has often emphasized lab-based thermal limits (CT_max/CT_min), frequently overlooking field behavioral observations. This limits insight into species adaptation under climate change and biological invasions. Our study bridges this gap by integrating laboratory CT_max data with field recordings to examine thermal responses in foraging activities of native and exotic ants in subtropical Hong Kong. We collected 846h of field behavior data alongside substrate temperatures and measured CT_max for 748 workers across five exotic and six native species, constructing thermal performance curves (TPC) to assess temperature responses. By further incorporating a decade of local foraging records (10,023 entries) and thermal limits for 50 native species (2,218 data points), we found comparable CT_max between exotic and native ants, but exotic species exhibited lower thermal sensitivity (Q₁₀). Exotic ants also demonstrated varied thermal strategies: three species showed broader thermal niches, consistent with thermal generalism and competitive exclusion, while two others had narrower niches yet higher activity speeds than natives. Overall, warming trends may favor exotic species, potentially exacerbating their ecological impact.