Vol. 9, Issue 11, Part A (2025)

The decomposition of organic remains is a complex ecological process governed by intricate interactions among insects, microorganisms, and environmental factors. This review comprehensively examines the colonisation dynamics and behavioural ecology of insects associated with human cadavers and animal carcasses, emphasizing their significance in forensic investigations. Over the past two decades (2005-2025), research has advanced substantially in understanding the role of necrophagous Diptera and Coleoptera in mediating tissue breakdown and providing crucial evidence for postmortem interval (PMI) estimation. Early colonisers, such as blowflies (Calliphoridae) and flesh flies (Sarcophagidae), exhibit predictable oviposition, feeding, and breeding behaviours influenced by temperature, humidity, and habitat type. Comparative analyses reveal broad ecological similarities between human and animal decomposition but also highlight physiological and microbial differences affecting colonisation timing, volatile organic compound (VOC) emission, and insect succession. Recent studies integrating molecular diagnostics, microbial profiling, and volatile analysis have improved accuracy in species identification and PMI estimation. Furthermore, the emerging field of entomotoxicology has demonstrated the potential of insect larvae as biological indicators of drugs and toxicants in advanced decomposition. Environmental and ecological determinants-including microclimate, seasonality, soil type, and vegetation-profoundly influence decomposition trajectories and insect behaviour, particularly in tropical regions such as India. Despite these advancements, gaps persist in methodological standardization, region-specific reference datasets, and the effects of climate change on insect distribution. Future research should focus on standardized global protocols, molecular integration, and climate-adaptive forensic models to enhance precision and reproducibility. This synthesis underscores that a comprehensive understanding of insect behaviour and colonisation ecology is fundamental to modern forensic science, bridging biological theory with practical legal application.