Background:This study investigates the impact of Albopleistophora grylli, a newly identified microsporidian parasite, on the cricket species Gryllus bimaculatus and Gryllus assimilis, which are commonly cultured for food and feed. Microsporidia are obligate intracellular parasites that can significantly affect host physiology and survival, especially in dense rearing conditions. The research addresses the potential risks of A. grylli in commercial cricket rearing, focusing on its effects on cricket survival, development, and fecundity. Results: The study found that while microsporidian exposure had minimal impact on survival rates at low and medium cricket densities, high densities led to decreased survival regardless of exposure. Exposed crickets had slightly higher feed intake and faeces production, possibly indicating compensatory feeding behavior. Furthermore, exposed males displayed higher weights than non-exposed males, particularly at lower densities. No significant effect of microsporidian exposure on fecundity was observed, although a marginal interaction effect suggested reduced fecundity at higher densities in exposed females. Additionally, microsporidian spores were successfully detected in almost all exposed crickets, confirming efficient infection. Conclusions: The findings suggest that A. grylli poses limited direct risk to cricket survival and reproduction under typical rearing densities, although higher densities exacerbate survival risks. The compensatory feeding behavior observed in infected crickets may indicate an adaptive host response to infection. Overall, while A. grylli infection does not heavily impact cricket rearing at controlled densities, the study underscores the need for careful density management and continuous monitoring of microsporidia in cricket farming to mitigate potential risks in high-density conditions