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Forensic entomology is an important field of forensic science that utilizes insect evidence in criminal investigations. Blow flies (Diptera: Calliphoridae) are among the first colonizers of remains and are therefore frequently used in determining the minimum postmortem interval (mPMI). Blow fly development, however, is influenced by a variety of factors

Forensic entomology is an important field of forensic science that utilizes insect evidence in criminal investigations. Blow flies (Diptera: Calliphoridae) are among the first colonizers of remains and are therefore frequently used in determining the minimum postmortem interval (mPMI). Blow fly development, however, is influenced by a variety of factors including temperature and feeding substrate type. Unfortunately, dietary fat content remains an understudied factor on the development process, which is problematic given the relatively high rates of obesity in the United States. To study the effects of fat content on blow fly development we investigated the survivorship, adult weight and development of Lucilia sericata (Meigen; Diptera: Calliphoridae) and Phormia regina (Meigen; Diptera: Calliphoridae) on ground beef with a 10%, 20%, or 27% fat content. As fat content increased, survivorship decreased across both species with P. regina being significantly impacted. While P. regina adults were generally larger than L. sericata across all fat levels, only L. sericata demonstrated a significant (P < 0.05) difference in weight by sex. Average total development times for P. regina are comparable to averages published in other literature. Average total development times for L. sericata, however, were nearly 50 hours higher. These findings provide insight on the effect of fat content on blow fly development, a factor that should be considered when estimating a mPMI. By understanding how fat levels affect the survivorship and development of the species studied here, we can begin improving the practice of insect evidence analysis in casework.

ContributorsNoblesse, Andrew (Author) / Weidner, Lauren (Thesis director) / Parrott, Jonathan (Committee member) / School of Mathematical and Natural Sciences (Contributor) / Barrett, The Honors College (Contributor)
Created2021-05
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Beginning in the early 1990s, nuclear forensic science is a relatively young field that focuses on “re-establishing the history of nuclear material of unknown origin” (Mayer, et al. 2010, p. 1). Specifically, investigators compare these unknown materials, pre-detonation in this case, based on their characteristics and process history (Mayer, et

Beginning in the early 1990s, nuclear forensic science is a relatively young field that focuses on “re-establishing the history of nuclear material of unknown origin” (Mayer, et al. 2010, p. 1). Specifically, investigators compare these unknown materials, pre-detonation in this case, based on their characteristics and process history (Mayer, et al. 2010, p. 1). In 2010, the Committee of Nuclear Forensics made ten recommendations on the procedures that could lead to improvement in investigation methods. In particular, this paper discusses Recommendation 6: “The nuclear forensics community should develop and adhere to standards and procedures that are rooted in the applicable underlying principles that have been recommended for modern forensic science, including calibration using reference standards; cross-comparison with other methods; inter-laboratory comparisons; and identification, propagation, and characterization of uncertainties'' (Committee of Nuclear Forensics, 2010, p. 11). The main objective of this paper is to compile a literature review to determine how this recommendation was followed, if at all, and produce a list of suggestions that could complement any effort towards the improvement of the field. Out of the methods recommended, that which has fostered the most growth has been cross-comparison. For example, the need for human supervision has decreased, which has decreased the need for human error (Reading, et al., 2017, p. 6013). However, areas that would benefit from development are increasing the number of disciplines in the field (Croudace, et al., 2016, p. 128). These conclusions provided the basis for improvements to other existing studies like DNA and fingerprinting.

ContributorsSarraf, Yasmine (Author) / Montero, Shirly (Thesis director) / Sellner, Erin (Committee member) / van Zalen, Ed (Committee member) / Barrett, The Honors College (Contributor) / School of Social and Behavioral Sciences (Contributor) / School of Mathematical and Natural Sciences (Contributor) / School of Complex Adaptive Systems (Contributor)
Created2021-12
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The steroid hormone 20-hydroxyecdysone (20E) controls molting in arthropods. The timing of 20E production, and subsequent developmental transitions, is regulated by a variety of factors including nutrition and photoperiod. Environmental factors, such as temperature, play a critical role in regulation as well. The increasing prevalence of urban heat islands (UHI),

The steroid hormone 20-hydroxyecdysone (20E) controls molting in arthropods. The timing of 20E production, and subsequent developmental transitions, is regulated by a variety of factors including nutrition and photoperiod. Environmental factors, such as temperature, play a critical role in regulation as well. The increasing prevalence of urban heat islands (UHI), or areas with elevated temperature due to retained heat by built structures, in response to rapid urbanization has made it critical to understand how organisms respond to elevating global temperatures. Some arthropods, such as the Western black widow spider, Latrodectus hesperus, appear to thrive under UHI conditions, but the physiological mechanism underlying their success has not been explored. Recently, we have shown that L. hesperus, a troublesome urban pest, in fact responds to urban heat island conditions in Phoenix, AZ with delayed development, reduced body mass, and increased mortality. Here we look at the relationship between 20E levels and development in spiderlings reared under desert (27ᵒC), intermediate (30ᵒC), and urban (33ᵒC) temperatures, filling a noticeable gap in not only understanding ecdysteroids’ role in arachnid development but how incremental changes in environmental conditions affect the regulation of this process. Developmental progression and hemolymph 20E titers were recorded for several families of spiders collected from across the urban Phoenix area with data spanning from day 55 to 75 of development, focusing on the second developmental instar. We found that 33°C, but not 30°C, led to 1) a significantly higher production of 20E throughout development, 2) a reduced and delayed molt-inducing 20E peak, and 3) noticeable reductions in growth rate and mass. At 30°C, a variable response is seen in molt timing, without the negative impacts on size and mortality as seen at 33°C, suggesting that at UHI temperatures, the optimal developmental temperature threshold has been surpassed.
Created2019-05