Endosymbiotic bacteria that obligately associate with entomopathogenic nematodes as a complex are a unique model system to study competition. These nematodes seek an insect host and provide entry for their endosymbionts. Through their natural products, the endosymbionts nurture their nematodes by eliminating secondary infection, providing nutrients through bioconversion of the insect cadaver, and facilitating reproduction. On one hand, they cooperatively colonize the insect host and neutralize other opportunistic biotic threats. On the other hand, inside the insect cadaver as a fighting pit, they fiercely compete for the fittest partnership that will grant them the reproductive dominance. Here, we review the protective and nurturing nature of endosymbiotic bacteria for their nematodes and how their selective preference shapes the superior nematode-endosymbiont pairs as we know today.

与昆虫病原线虫复杂结合的内共生细菌是研究竞争的独特模型系统。这些线虫寻找昆虫宿主并为其内共生菌提供入口。内共生菌通过它们的天然产物，通过消除继发感染来培育线虫，通过昆虫尸体的生物转化提供营养，并促进繁殖。一方面，他们合作定居昆虫宿主，并中和其他机会性生物威胁。另一方面，在昆虫尸体内部作为战斗场，他们激烈竞争最适合的伙伴关系，从而赋予他们生殖优势。这里，