Screening the Candidate Postmortem Marker Genes for Estimating Postmortem Intervals in Nurse Bees(Apis mellifera)

The honey bee ( Apis mellifera) plays an essential role in global agriculture; however, colony losses have been frequently reported. Because several mRNAs remain active for a limited period after death, quantitative real-time PCR(qRT-PCR) analysis of mRNA degradation may be useful for estimating postmortem intervals(PMIs) in dead bees. In this study, the expression dynamics of thirteen candidate postmortem marker genes were analyzed in nurse bee carcasses from 1 to 7 days postmortem. Among them, RPS5 and RPS18 showed significant decreases in expression within the early postmortem phase(1-3 days). Based on cubic regression models, RPS5 (R² = 0.997) and RPS18 (R² = 0.982) demonstrated strong correlations with PMI. Further-more, expression ratios using stably expressed genes as denominators revealed that RPS5/ SDH and RPS18/ SDH achieved the highest coefficients of determination (R² = 0.996), distinguishing carcasses between 1-2 and 3-7 days postmortem. These findings suggest that RPS5, RPS18, and their ratios with SDH can serve as molecular markers for PMI estimation in nurse bees. This molecular approach may support forensic analyses of honey bee mortality under both laboratory and field conditions.