Browsing by Subject "Forensic entomology"
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Item Fitness Effects of Colonization Time of Chrysomya rufifacies and Cochliomyia macellaria, and their Response to Intra- and Inter-specific Eggs and Egg Associated Microbes(2012-07-16) Brundage, AdrienneChrysomya rufifacies and Cochliomyia macellaria are two medically and forensically important necrophagous flies that dominate ephemeral resources in the southern US. Since its introduction in 1981, Ch. rufifacies has become established throughout the New World due to its larvae being facultative predators. Through this research I examined the interaction between the native, primary colonizer C. macellaria and the invasive, secondary colonizer Ch. rufifacies and elucidated the olfactory mechanisms used to locate, colonize, and exploit ephemeral resources. This work used competition experiments, olfactometer experiments, and high-throughput sequencing to investigate the effects of priority colonization of ephemeral resources on both species, the olfactory mechanisms employed by gravid females to locate a resource, and the effects of egg-associated volatiles on those females. Results from competition experiments indicated that priority sequence significantly affected the fitness of both C. macellaria and Ch. rufifacies. Regulation of colonization time is not chiefly governed by resource age, as previously thought, but is affected by colonization of the resource by conspecific and heterospecific individuals. Colonizing adults may use cues from early colonizers to assess resource quality. These cues may be derived from the physiology of the eggs, the 31-39 species of bacteria I determined are present on the egg chorion, or some combination of both. Design of these experiments facilitated the development of techniques to surface-sterilize Calliphoridae eggs, analyze behavior of adults in a dual choice olfactometer, and associate adult response to conspecific and heterospecific eggs with environmental cues that ultimately affect larval fitness.Item Spatial and temporal variation in carrion blow fly communities: applications to forensic entomology(Texas Tech University, 2001-05) Richards, Elizabeth NSeasonal and regional carrion decomposition studies were conducted in three geographic regions in Texas. Seasonal studies were replicated during the spring, summer and winter, for three consecutive years. Regional studies were replicated in one season (summer) for three consecutive years. Domestic pig carcasses (N=3) were placed 200m apart in each of the three study sites. Carcasses were monitored during the decay process to document spatial and temporal variation in decay patterns and in the composition of the associated blow fly communities. Distinct patterns of decomposition and distinct blow fly communities were correlated with season and these patterns were similar among geographic regions. However, the abundance of certain blow fly species did vary significantly by year. During pilot studies, Cochliomyia macellaria (F.) were the most abundant flies at all three sites. Thus, this species was the emphasis of two major sections of the dissertation: (1) an investigation of variation in wing morphology among populations across years, and (2) mitochondrial DNA variation among populations of C. macellaria. In the morphological study of C macellaria, 25 characters were measured from the right wing of each specimen in order to investigate intraspecific variation. Multivariate statistical analyses were performed, and significant variation was found among populations and across years. In the molecular study of C. macellaria, the entire cytochrome oxidase subunit II (COII) gene was sequenced (693bp) for each individual in order to investigate intraspecific variation. Regional variation was documented among the three geographic locations. DNA sequences generated in this study are deposited in GenBank. Results from this dissertation are discussed in terms of their application to forensic entomology. Entomological evidence collected from crime scenes can assist criminal investigations in numerous ways. Community succession and insect developmental timing can be used to establish a postmortem interval (PMI or time since death). Geographic distributions can be used to determine whether human remains have been relocated following death. This work is the first replicated decomposition study in the state of Texas and contributes significantly to a growing national database in forensic entomology. It is the only fully replicated study, in any US state, to extend across three consecutive years. In addition, this dissertation is the first study to apply both molecular and multivariate statistical techniques to forensic entomology, in an effort to enhance the detection of postmortem relocation of human remains.