Combined elevated temperature and CO2 alter Wolbachia abundance and host fitness but not cytoplasmic incompatibility in a stored-product pest

Elevated temperature plus CO2 (32°C, ~1000 ppm) shifts Wolbachia strain abundance in coinfected Callosobruchus chinensis, with Ori declining and Con increasing, while CI stays stable.

• Why it matters: Coinfecting Wolbachia strains may respond differently to climate-like conditions, potentially changing host performance and the reproductive incompatibility that shapes symbiont spread.
• What they did: Beetles from an isofemale line and derived Con-only and uninfected sublines were kept at 30°C, ~500 ppm CO2 or eT&CO2; Wolbachia relative abundance and CI intensity were measured, alongside life-history traits across generations.
• The result: CI expression remained stable across conditions, but eT&CO2 reduced egg-laying by coinfected females and altered development, longevity, and fecundity across traits and generations; equilibrium analyses indicated lower infection persistence in F1 but higher persistence in F2 under eT&CO2.

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