Nocturnal oviposition of the forensic scuttle fly, Megaselia scalaris (Loew) (Diptera: Phoridae) indoors

Abstract

In forensic entomology, nocturnal oviposition of flies could reduce discrepancy of minimum post-mortem interval (PMImin) estimation which is due to assumption that oviposition only occurs during day time hours. Previous records indicate that some forensic species of Calliphoridae and Sarcophagidae displayed nocturnal oviposition and larviposition but such occurrences can be inconsistent. Apart from blow flies and flesh flies, the scuttle flies (Diptera: Phoridae) are known to be forensically important indoors and they exhibit diurnal and nocturnal behaviour. To investigate if oviposition by scuttle flies occurs during night or day time hours, baited scuttle fly traps consisting decomposed cow’s liver were placed inside the Forensic Entomology Laboratory, Faculty of Health Sciences, Universiti Kebangsaan Malaysia on diurnal and nocturnal intervals. The traps were divided into two groups, i.e. light-exposed and total dark conditions. It was discovered that all specimens collected were Megaselia scalaris (Loew) and they were active and performed oviposition during day and night times. Light exposure did not affect oviposition activity during diurnal and nocturnal periods. Therefore, it is recommended that nocturnal oviposition must be taken into consideration when using this fly as reference for PMImin estimation.