Purpureocillium lilacinum and Pochonia chlamydosporia as biocontrol agents: a comparative review of efficacy, ecology, and integrated application.

Plant-parasitic nematodes cause annual global crop losses, driving the urgent demand for sustainable alternatives to synthetic nematicides to control them. Among biological control agents, Purpureocillium lilacinum and Pochonia chlamydosporia have emerged as the most promising egg-parasitic fungi. However, their comparative biology and deployment contexts remain incompletely understood. This review synthesizes the current knowledge on their taxonomy, ecology, molecular genomics, parasitism mechanisms, biocontrol efficacy and commercial formulations. Both fungi parasitize eggs of economically destructive genera, Meloidogyne, Heterodera, and Globodera, but differ fundamentally in their ecological niches, infection mechanisms, and molecular arsenals. P. lilacinum exhibits broader ecological versatility, infecting multiple nematode life stages and producing nematicidal leucinostatins, whereas P. chlamydosporia specializes in egg parasitism, establishes stable rhizosphere endophytism, and primes systemic plant defenses via pochonin metabolites. Comparative genomics revealed shared serine proteases and chitinolytic enzyme arsenals for eggshell penetration, alongside species-specific virulence determinants shaped by positive selection and gene duplication. Field and greenhouse studies have consistently demonstrated substantial suppression of nematode egg populations, although efficacy remains strongly dependent on the fungal isolate and environmental conditions. Integration with other biocontrol agents, organic amendments, and reduced-dose nematicides consistently outperformed single-agent applications. Emerging nanoemulsion and blastospore-based formulations show promise in overcoming the persistent challenges of UV sensitivity and shelf life instability. Rather than redundant alternatives, these fungi offer complementary biological solutions, providing a mechanistic rationale for combined deployment within crop-specific, integrated pest management frameworks.