Date of Award

Spring 5-31-2017

Document Type

Thesis

Degree Name

Master of Science (MS)

Department/Program

Forensic Science

Language

English

First Advisor

Jennifer Rosati

Second Reader

Nathan Lents

Third Advisor

Hunter Johnson

Abstract

During decomposition, there are many different insects groups that utilize carrion as a resource. In particular, blow flies (Order: Diptera; Family: Calliphoridae) are considered to be a forensically important family due to their ability to rapidly locate and colonize a carrion resource. As a result, blow flies are commonly used as indicator species in PMI estimations. However, recent research indicates that the colonization behavior of these species can be influenced by a variety of abiotic and biotic factors. In this study, the effects of arrival order, resource quality and bacterial or species cues on the oviposition behavior of Phormia regina were investigated. Colony cages containing gravid P. regina females (100) and males (50) were exposed to resources of different quality (fresh vs. aged pork liver), species presence/absence (with or without Lucilia sericata eggs) and bacterial cues (sterilized vs. unsterilized L. sericata eggs). To test the effect of resource quality, fresh and aged pork liver was used. To test the effect of arrival order, colonization by L. sericata was simulated using eggs collected from L. sericata colony cages that were immediately placed on both the fresh and aged liver. To test the effect of bacterial cues, freshly collected L. sericata eggs were immediately placed on liver or were subjected to a sterilization treatment to remove bacteria prior to placement on the resource and subsequent exposure to P. regina for colonization. These factors affected not only the amount of eggs laid on the resource and the locations of oviposition, but also influenced the time of colonization in each treatment. The colonization behavior of P. regina was quantified by measuring the time to colonization, location and amount of eggs laid in each treatment condition. Fresh liver without L. sericata eggs was used as a control. The results from this study can improve our knowledge and understanding of the mechanisms driving the colonization behavior for forensically important blow flies and validate their use as indicator species for the estimation of the minimum time of colonization.

 
 

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