Preserving host‐egg usability beyond mold control: a sorbic acid–lysozyme system for mass rearing the egg‐parasitic mite Paracarophenax alternatus

Abstract BACKGROUND Host‐egg preservation is a major bottleneck in the mass rearing of the egg‐parasitic mite Paracarophenax alternatus , a potential biological‐control resource targeting Monochamus alternatus , the principal vector of pine wilt disease in East Asia. Preserved host eggs must resist microbial deterioration while remaining suitable for mite acceptance, physogastric development and offspring production. This study aimed to develop a sequential preservation–compatibility framework integrating mold control with host‐use performance. RESULTS A 15 min dipping window standardized exposure. Sorbic acid showed the most favorable mold‐control profile among single preservatives, and solvent–concentration optimization identified 1.6 g L −1 sorbic acid in 75% ethanol as the short‐cycle benchmark, combining no visible mold at 8 days with 100% selective parasitism and the highest physogastric‐female production among no‐mold formulations. In the 16 days validation assay, SA‐L3 (1.6 g L −1 sorbic acid plus 1.5 g L −1 lysozyme in 50% ethanol) maintained no visible mold through 12 days, reached 7.3% mold incidence at 16 days and had the lowest 4–16 days mold‐incidence area under curve (14.67% d). It retained full selective parasitism, benchmark‐level physogastric‐female production, high physogastric body volume and stable developmental duration. The host‐use index (HUI = 0.994), sensitivity analysis and principal component analysis consistently ranked SA‐L3 first. CONCLUSION Host‐egg preservation for Paracarophenax alternatus cannot be optimized by mold control alone. Joint evaluation of microbial stability and host‐use performance identified SA‐L3 as the leading long‐cycle candidate under the tested laboratory conditions. This preservation–compatibility framework provides a quantitative basis for host‐substrate quality control in Paracarophenax alternatus mass rearing and related natural‐enemy production systems. © 2026 Society of Chemical Industry.