Diurnal Oviposition Timing of Blow Flies and DNA Identification of Early Arrivers

Faculty Sponsor

Kristi Bugajski


Arts and Sciences



Presentation Type

Poster Presentation

Symposium Date

Spring 4-23-2016


Forensic entomology is the use of insects in the criminal justice system. Blow flies (Diptera: Calliphoridae) are usually the first insects to arrive and oviposit (lay eggs) on carrion. Their early arrival makes the timing of blow fly oviposition critical for postmortem interval (PMI) calculations. The PMI is the time that has passed between death and corpse discovery. There is little known about the diurnal timing of oviposition in forensic entomology. This study documented the earliest oviposition time in relation to hours after sunrise. Three pigs were placed in a field one hour after sunrise and observed hourly for the presence of blow flies and oviposition. Three bait cups filled with aged chicken liver were also placed in the field to note differences in oviposition timing and magnitude between pigs and liver. The experiment was replicated three times in September, 2015. No oviposition was observed on any of the chicken liver bait cups. The earliest oviposition on pigs occurred four and a half hours after sunrise but adult flies were observed starting two hours after sunrise. Egg masses were collected from pigs immediately after oviposition to ensure the first blow fly species ovipositing was recorded. Egg masses were frozen in a -20°C freezer prior to DNA isolation. DNA from egg masses was isolated and the mitochondrial cytochrome oxidase I (CO I) gene was amplified by PCR. CO I sequences specific to individual blow fly species were identified using BLAST. The two blow fly species identified were Lucilia coeruleiviridis (Macquart) and Lucilia illustris (Meigen). These results confirm previous findings that Lucilia species are early arrivers on carrion. It is important to note that blow flies did not start ovipositing immediately after sunrise, and forensic entomologists should take this into consideration when making PMI estimations.

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