From infection barriers to efficacy enhancement: mechanistic strategies for entomopathogenic fungal biocontrol

Entomopathogenic fungi (EPF) are important microbial control agents, yet their efficacy is often constrained by variable host susceptibility, fungal fitness, and environmental conditions. We examine four interconnected processes during EPF infection: adhesion and germination on the insect cuticle, cuticle penetration, survival and proliferation within the hemocoel, and infection-associated changes in host behavior and transmission. For each process, fungal virulence mechanisms and insect countermeasures are evaluated based on the strength of supporting evidence and their generality across fungal and insect taxa. These mechanistic insights are then linked to strategies for improving EPF efficacy, including strain optimization, environmental stress priming, genetic manipulation, RNA interference, mycovirus-mediated phenotypic modification, and microbiome-based approaches. Particular attention is given to whether enhanced virulence comes at the cost of fungal growth, persistence, host specificity, or delivery. By linking mechanistic insights at each stage of infection to corresponding intervention strategies, this review offers a framework for prioritizing approaches that can improve the reliability of EPF-based pest management.