Thermal Tolerance Contributes to the Competitive Displacement of Meloidogyne incognita by Meloidogyne enterolobii

Meloidogyne enterolobii has been displacing Meloidogyne incognita as the dominant root-knot nematode (RKN) species in Hainan, China, with ongoing northward expansion. This study examines whether and how thermal tolerance contributes to this competitive displacement by comparing survival and reproductive traits of both species across a 10–55°C gradient. Meloidogyne enterolobii exhibited significantly lower mortality in second-stage juveniles (J2s) and eggs under all tested conditions, with superior survival particularly pronounced under short-term high-temperature stress (≥40°C for ≤7 days) and prolonged low-temperature exposure (10–15°C for ≥9 days). At ≥25°C, M. enterolobii produced 1.04–1.54× more egg masses and achieved higher fecundity (1.06–1.80×) than M. incognita , while the latter retained limited reproduction at 20°C (0.57 ± 1.51 egg masses/plant at 38 days post-inoculation). At elevated temperatures (30–35°C), the reproduction factor (RF) of M. enterolobii exceeded that of M. incognita by 27.4–130.3%, indicating a distinct competitive advantage under warming. However, at 25°C, M. incognita showed a higher RF, suggesting a context-dependent fitness pattern that we interpret within the framework of survival–reproduction trade-offs. These findings provide experimental evidence that superior thermal tolerance contributes to the competitive displacement of M. incognita by M. enterolobii , and offer actionable insights for predicting nematodes distribution shifts and designing thermal-based management strategies to mitigate agricultural losses under climate change.