Temperature effects on development and cuticular hydrocarbons in forensically relevant Dermestes maculatus

Dermestes maculatus, a globally distributed beetle of significant forensic importance, is commonly found on decomposing remains, its presence on corpse aiding in post-mortem interval (PMI) estimation and is economically important due to its destructive feeding on stored animal products. Its cuticle contains species-specific cuticular hydrocarbons (CHCs), which vary with developmental stage, sex, and environmental conditions. This study investigated the use of larval body size (length, head capsul width, and weight) and CHC profiles as potential indicators of larval age under controlled rearing temperatures (20 °C, 30 °C, and 40 °C). Adult beetles were collected, identified morphologically and through mitochondrial cytochrome oxidase I (mtCOI) gene sequencing, and bred and reared to obtain larvae. Larvae were reared under laboratory conditions (60% RH, 12:12 h L: D light-dark cycle) at the three temperature regimes. Developmental duration and morphometric data were recorded across instars, and CHCs were analyzed via gas chromatography-mass-mass spectrometry (GC- MS) in the 2nd, 4th and 6th instars. Results demonstrated a temperature-dependent decrease in developmental time and an increase in larval size between 20 °C and 30 °C, while development was arrested at 40 °C, with high egg mortality. CHC profiles varied significantly with instar and temperature, highlighting their sensitivity to both intrinsic and extrinsic factors. These findings demonstrate that morphological measurements and cuticular hydrocarbon analysis are reliable indicators of larval age in D. maculatus, although validation under field conditions is required before routine application to forensic post-mortem interval estimation.