A report of Pheidole megacephala (Fabricius 1793) (Hymenoptera: Formicidae) colonisation on small and medium-sized mammal carcasses: its implications in forensic entomology

• Published in: INTERNATIONAL JOURNAL OF TROPICAL INSECT SCIENCE
• Main Authors: Ahmad, Azwandi; Omar, Baharudin
• Format: Article
• Language: English
• Published: SPRINGER INT PUBL AG 2023
• Subjects: Entomology
• Online Access: https://www-webofscience-com.uitm.idm.oclc.org/wos/woscc/full-record/WOS:001169113100006
• ISSN: 1742-7584; 1742-7592
• DOI: 10.1007/s42690-023-01072-w

Decomposition is a natural nutrient cycling process that begins with internal bacterial activities and followed by the occupation of various invertebrates, including ants. We reported a significant colonisation of big-headed ants, Pheidole megacephala (Fabricius 1973) on small and medium-sized mammal in a tropical rain forest in Selangor, Malaysia. Three rats (Rattus norvegicus, weight = 0.508 +/- 0.023 kg) and three long-tailed macaques (Macaque fascicularis, weight = 5.750 +/- 0.776 kg) carcasses were left to decompose naturally. Large P. megacephala colonies were constructed in two out of six carcasses represented by one rat and one macaque. The remaining four carcasses were undisturbed and decomposed naturally. For the colonised rat carcass, P. megacephala covered the entire carcass with soil particles, whereas for the colonised macaque carcass, it was partly covered. After six days of decomposition, the colonised macaque body mass reduced by 22.90%, which was lower than the other two non-colonised macaque carcasses with 80.06% and 83.41%, respectively. From the final hours of day three until day five of decomposition, the colonised macaque rectum body temperature was lower than the non-colonised macaque carcasses. Flies were not seen in colonised rat carcass until day five of decomposition. However, for the colonised macaque, their arrival timing was comparable to the uncolonised carcasses, but the number of flies reduced. In conclusion, P. megacephala colonisation on rat and macaque carcass had slowed down the decomposition rate, reduced internal body temperature and the abundance of flies. If these aspects are overlooked by forensic entomologists, it can potentially lead to an inaccurate postmortem interval (PMI) estimation.