Impact of temperature and pH variations on intergeneric interactions and proteomic responses in rhabditid nematodes

Nematodes are one of the most abundant and ecologically significant organisms, yet they are affected by environmental fluctuations; however, their intergeneric interactions under environmental stressors remain underexplored. This study explores the impact of pH and temperature differences on the growth, reproduction, and proteomic responses of four rhabditid nematode species of four genera (Bursilla monhystera, Diploscapter coronatus, Mesorhabditis spiculigera, and Protorhabditis parvus). Using controlled culture conditions, we examined intergeneric competition under low pH (4) and high temperature (35 °C) stress for six and four weeks, respectively. Experiments carried out were completely randomized with 20 replicates each and analysis of variance with interactions models were carried out to determine the impacts of low pH and high temperature treatments. Nematode growth and survival were significantly affected, with tolerant species (D.coronatus and P. parvus) exceeding sensitive complements (B.monhystera and M. spiculigera) in both the stress conditions. Temperature was the most influential factor in reducing nematode lifespan, brood size, and locomotion. Proteomic analysis of temperature-tolerant (D. coronatus) and temperature-sensitive (B. monhystera) nematodes showed 26 differentially expressed proteins (DEPs), mainly involved in metabolism, stress response, and cellular processes. Heat shock proteins (hsp-70, hsp-6) and antioxidant enzymes (glutathione peroxidase, superoxide dismutase) were upregulated in D. coronatus, demonstrated enhanced stress tolerance, whereas proteins associated with growth and reproduction were downregulated in B. monhystera, resulting in reduced fitness. These outcomes highlight genus-specific adaptive mechanisms for environmental stress and provide insights into the molecular basis of nematode resilience. The current study enhances our understanding of nematode ecology and their possible responses to climate-induced stressors.