Presentation Title

Crime Stopping Insects: A Fly’s Point of View

Faculty Mentor

Levi Zahn, Alec Gerry

Start Date

18-11-2017 10:45 AM

End Date

18-11-2017 11:00 AM

Location

9-271

Session

Bio Sciences 2

Type of Presentation

Oral Talk

Subject Area

biological_agricultural_sciences

Abstract

Medicocriminal Entomology is a lesser known application of Forensic Science involving the utilization of necrophagous and/or carnivorous arthropods as evidence to be used in solving crimes. Medicocriminal Entomology, more widely referred to as Forensic Entomology, unites aspects of human decomposition and the adversarial justice system. The data collected by Forensic Entomologists can be used to attain the time of insect colonization, the period of insect activity, and subsequently, an estimation of the post mortem interval. On decaying organic matter, insects arrive in successional waves that correspond to different stages in the decay process. However, various intrinsic and extrinsic factors can greatly challenge the ability to obtain consistent insect successional data. Therefore, to begin to understand southern Californian insect succession during winter months, and to demonstrate to the general public the duties of a Forensic Entomologist, a swine carcass was exposed to natural environmental conditions for a two-and-a-half-month period. The carcass was photographed and surveyed once a day for the first four weeks, and every other day for the remainder of the experiment. Insect collections took place during every survey. The surveys concluded that the primary colonizers of the pig carcass consisted mostly of insect species from the families Calliphoridae, Phoridae, Piophilidae, Histeridae, and Dermestidae. These families were noted as abundantly present as adults and immatures (both visually and via collections) throughout the experiment, though not all coincided with the same decomposition stages. Insects collected from the carcass as eggs or larvae were reared in lab and determined to primarily be Calliphoridae. These samples were utilized to estimate the post-mortem interval from daily developmental information for each species. Replicates of this experiment need to be conducted for each season in order to more accurately develop insect succession models specific to southern Californian medicocriminal cases.

Summary of research results to be presented

The results to be presented are in two main parts. The first of which will include a general summary of Mediocriminal Entomological sciences, as well as the biological impacts of decomposition and insect necrophagy. In addition, proper insect evidence collection protocol and forensic scene behavior will be detailed in this section. In part two, a summary of the experiment will be given. All of the insect families identified from the experiment in collections will be reviewed with short but concise ecological descriptions. The step-by-step calculation of the post-mortem interval using keystone Diptera species (Lucilia sericata, Lucilia Mexicana, and some specimens from the Chrysominae) collected during the experiment will be showcased in this portion. The current scientific debate on insect evidence use for post-mortem estimations will also be discussed. The presentation will conclude on a conversation about future work that must be conducted in order to settle this current debate, and further Medicocriminal sciences.

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Nov 18th, 10:45 AM Nov 18th, 11:00 AM

Crime Stopping Insects: A Fly’s Point of View

9-271

Medicocriminal Entomology is a lesser known application of Forensic Science involving the utilization of necrophagous and/or carnivorous arthropods as evidence to be used in solving crimes. Medicocriminal Entomology, more widely referred to as Forensic Entomology, unites aspects of human decomposition and the adversarial justice system. The data collected by Forensic Entomologists can be used to attain the time of insect colonization, the period of insect activity, and subsequently, an estimation of the post mortem interval. On decaying organic matter, insects arrive in successional waves that correspond to different stages in the decay process. However, various intrinsic and extrinsic factors can greatly challenge the ability to obtain consistent insect successional data. Therefore, to begin to understand southern Californian insect succession during winter months, and to demonstrate to the general public the duties of a Forensic Entomologist, a swine carcass was exposed to natural environmental conditions for a two-and-a-half-month period. The carcass was photographed and surveyed once a day for the first four weeks, and every other day for the remainder of the experiment. Insect collections took place during every survey. The surveys concluded that the primary colonizers of the pig carcass consisted mostly of insect species from the families Calliphoridae, Phoridae, Piophilidae, Histeridae, and Dermestidae. These families were noted as abundantly present as adults and immatures (both visually and via collections) throughout the experiment, though not all coincided with the same decomposition stages. Insects collected from the carcass as eggs or larvae were reared in lab and determined to primarily be Calliphoridae. These samples were utilized to estimate the post-mortem interval from daily developmental information for each species. Replicates of this experiment need to be conducted for each season in order to more accurately develop insect succession models specific to southern Californian medicocriminal cases.