Browsing by Author "Pechal, Jennifer"
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Item Intraspecific Gene Flow and Vector Competence among Periplaneta americana Cockroaches (Blattodea: Blattidae) in Central Texas(2010-01-16) Pechal, JenniferOne of the most overlooked areas in forensic entomology is urban, which applies to insects and their arthropod relatives that have interactions with humans, their associated structures, and companion animals. American cockroaches, Periplaneta americana (L.), are common pests of urban environments. Analyzing spatial distribution of P. americana populations in an artificial, outdoor environment provided insight of gene flow among populations collected in central Texas. This information provides for a better understanding of how and if populations were segregated, or if there was a single unified population. Populations can be genetically differentiated through determining variation of specific gene regions within populations. This study revealed a ubiquitous distribution of cockroach populations, and their ability to indiscriminately inhabit areas within an urban environment. Overall, cockroaches were identified from a large interbreeding population with no discernable relationship between genetic variation of P. americana and spatial distribution. Identifying cockroach populations is relative to understanding the ability of surrogate species indirectly affecting man by their ability to transfer disease-causing organisms including bacteria. This may have potentially deleterious health consequences on animal and/or human populations. There are several pathogens associated with cockroaches which are overlooked during diagnosis of sudden ailments with symptoms being similar to food-borne illnesses, including abdominal cramping, diarrhea, nausea, and fever. Analyzing spatial distributions of Escherichia coli and Campylobacter spp. in relationship to collected cockroaches allowed for prevalence of bacteria species to be identified among populations. The prevalence of bacteria isolated from total populations collected indicated a high prevalence (92.3%) of bacteria carried by the exoskeleton of P. americana. Gram-negative bacteria acquisition and dissemination of organisms such as E. coli was prevalent on campus. Screening for E. coli 1057:H7 and Campylobacter spp. resulted in no positive colony growth. The lack of Campylobacter spp. growth from cuticular surfaces may have resulted from undesirable conditions required to sustain colony growth. Data from this study corroborates the potential ability of cockroaches to mechanically transmit pathogens.Item The Importance of Microbial and Primary Colonizer Interactions on an Ephemeral Resource(2012-07-16) Pechal, JenniferCarrion decomposition is an essential ecosystem function as it is an important component of nutrient cycling. Carrion decomposition has primarily been attributed to insect consumption, with little attention given to microbial communities or their potential interactions with insects. The first objective was to use passive insect-trapping methods to assess primary colonizer communities on swine carcasses between two treatments: 1) carrion with access to insects and 2) carrion excluded from insect access for five days using exclusion cages. Despite similarities between succession patterns within each treatment, carcasses initially exposed to insects had significantly fewer insect taxa. Therefore, collections of adult insect communities associated with carrion are promising as an indication of whether or not there has been a delay in insect colonization of a resource. There has yet to be a study documenting bacterial communities during carrion decomposition. The second objective was to describe bacterial community succession and composition during decomposition in the presence and absence of naturally occurring insects. Total genomic DNA was used to identify bacterial community composition via a modified bacterial tagged encoded FLX amplicon pyrosequencing. I obtained 378,904 sequences and documented distinct bacterial community successional trajectories associated with insect access and exclusion carcasses. By the fifth day of decomposition, Proteus was the dominant (72%) bacterial genus on exclusion carcasses while Psychrobacillus (58%) and Ignatzschineria (18%) were dominant bacterial genera on insect carcasses. These data are the first to document bacterial community composition and succession on carrion. My final objective was to assess microbial community function in response to carrion insect colonization using metabolic profiling. I characterized microbial community metabolic function in the presence and absence of the primary necrophagous insects. I documented significant microbial community metabolic profile changes during active decomposition of carcasses. Mean carcass microbial community metabolic function with insect access continuously decreased over decomposition during both field seasons. Thus demonstrating microbial metabolic activity may have discriminatory power to differentiate early and late stages of decomposition. Overall, my data contributes to an understudied area of microbial research important to organic matter decomposition, forensic entomology, and microbial-insect ecological interactions.