Instars: A Journal of Undergraduate Research (Texas Digital Library - TDL E-Journals)
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220 research outputs found
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Effects of Quicklime on Insect Colonization
No full textEntomological evidence in the form of immature blow flies (Diptera: Calliphoridae) and flesh flies (Diptera: Sarcophagidae) are often used in forensic investigations to estimate the minimum postmortem interval (mPMI) using species-specific growth charts established under ideal conditions. Clandestine burials often do not fall within these ideal conditions, and insect colonization can be influenced by the presence of chemicals meant to enhance the rate of decay, such as lime. While lime in fact slows decomposition, the direct effect of the presence of lime on insect colonization is poorly represented in literature. Two lamb livers were used as analogues for human remains in a field experiment. They were left open to colonization both treated with lime and untreated and monitored for insect activity. By total number and stage of larvae collected, the results suggest a significant increase in attraction to the lime-treated liver, implying that lime might have acted as an olfactory attractant rather than an olfactory deterrent to gravid Sarcophagidae females
The Effect of Various Soil Types on Decomposition Rate
No full textThe decomposition rates of chicken carcasses in various soil types were observed and analyzed over a period of four weeks to determine if there were any major differences in how soft tissue decomposed in various environments. Three chicken carcasses were placed in plastic bins containing (a) sand (S), (b) topsoil (T), and (c) a compost/manure mixture (M). After the four week period, it was determined that the compost/manure mixture caused the fastest decomposition rate in the carcass followed by the topsoil and then the sand
Relationship between Mosquito Species Distribution and Human Population Density
No full textAbstract: Mosquitoes are known to exhibit different feeding behaviors, with some preferring to feed on mammals, others on birds, and so on. Many of them vector life-threatening diseases and pose a threat to public health and safety. When coupled together, mosquitoes that prefer to be around people could be more likely to transmit disease to those individuals. If it is possible to predict and map the potential mosquito species and vectors that are most closely associated with people, it would serve as an invaluable tool in combating disease. In an effort to see if this was possible, an experiment was done by surveying the mosquito larvae around College Station, TX in areas with varying population densities. The mosquitoes were identified down to the species taxonomic level and plotted against the population map of Brazos County. Mosquito species varied widely by location, with different feeding preferences per each area surveyed. When results were evaluated for any possible trends, it was found that areas with high populations did not show a preference for any one species or genus and did not yield species that preferred to feed on people. Key Words:relationship, mosquito, distribution, populatio
Effects of Water Temperature on Development and Survival to Adulthood in Culex quinquefasciatus (Diptera:Culicidae) and Psorophora ferox (Diptera:Culicidae) Larvae
No full textDue to the ability of mosquito species to survive in wide variety of temperatures, an experiment was conducted to test how water temperature affects the maturity rate of Culex and Psorophora species larvae and adults, two genuses that are common in College Station, Texas. Larval mosquitoes were reared in different temperature environments ranging from 9C to 34C to ascertain the effects of water temperature on the maturity and survival rates of mosquitoes. The data collected from this experiment revealed that mosquito larvae mature very quickly in optimal water temperatures, approximately 21C, and also can survive for extended periods of time, specifically 5 weeks during this experiment, in water that is below 10C. This data implicates that, during the colder months of November and December in Texas, large populations of mosquitoes could survive in their larval state in breeding pools and rapidly mature to adults during periods of uncharacteristic warm weather. These large influxes in mosquito populations coupled with reduced cold-weather mosquito control measures could result in higher disease transmission rates between humans and mosquitoes
Diet-based Sodium Regulation in 6th Instar Grasshoppers, Schistocerca americana (Drury) (Orthoptera: Acrididae)
No full textThis study analyzed sodium intake by Schistocerca americana (Drury) (Orthoptera: Acrididae) grasshoppers using three different seedling wheatgrass based diet treatments to simulate a natural food source. Sodium is a key nutrient for grasshopper cells, nerves, and reproduction. Grasshoppers acquire sodium from plants that they consume. However, it is unclear if grasshoppers self-regulate their sodium intake. Additionally, if grasshoppers self-regulate their sodium intake, the extent to which they do is uncertain. Newly molted 6th instar grasshoppers were fed one of three diets in which the level of sodium that they had access to was varied. The S. americana grasshoppers consumed significantly less of the 0.5 M added sodium only diet when presented with an option to choose between this diet and a no-sodium-added diet (t = 9.6026; df = 7; P < 0.0001). Grasshoppers in the 0.5 M added sodium only treatment consumed a significantly lower amount of food (P < 0.0001) as well as gained a significantly lower average mass (P < 0.0001) compared to the grasshoppers in the no-sodium-added only treatment. Our results generally correlated with previous studies on Locusta migratoria (L.) (Orthoptera: Acrididae) and information about the ecological tolerances and nutritional requirements of grasshoppers. Our data suggests that S. americana grasshoppers are capable of self-regulating their sodium intake. Additionally, we show that high concentrations of sodium in grasshopper diets have a negative effect on body mass. Our study illustrates that diet-based sodium regulation is a factor in the relationship between insect herbivores and their environments
Clarity of Shoe Impressions in Different Soil Types
No full textForensic science is a vastly expanding field as many different types of evidence and methods of analysis are being developed. One key type of evidence is impression evidence, and this experiment focused on shoe impressions made in soil. The research was based on how different types of soil at different moisture levels affects the clarity of shoe impressions. Shoe impressions were made in four various “types” of soil and three different impressions were made in each type. Molds were taken in plaster and then analyzed to see the clarity at which the shoe impressions could be made out. It was noted that none of the molds displayed individual characteristics and it was very different to observe even the basic tread of the shoe. The results show that the soil with the higher moisture levels made it overall easier to see and analyze the tread of the shoe and that soil that is more malleable, but not muddy, allows for shoe impressions to be more easily read
The Attractiveness of Various Household Baits to Drosophila melanogaster (Meigen) (Diptera: Drosophilidae)
No full textWhile Drosophila melanogaster (Meigen) (Diptera: Drosophilidae) has been well studied for its scientific uses as a model organism, not as much work has been put into controlling them as pests across the world. These fruit flies are a common nuisance to households everywhere, and can present health issues through spreading bacteria and other pathogens it comes into contact with onto the food we consume. Controlling them is largely done with baited traps which they are attracted to, but finding what substances they are most attracted to can improve the effectiveness of these traps. For this experiment, seven household substances including, apple cider vinegar, 20% sugar water, simple syrup, banana slices, mushroom slices, beer, and wine, were used to bait traps. These were all placed outside, to compare and test their attractiveness to D. melanogaster. It was found that after eight days out, bananas attracted the most flies, followed by mushrooms, apple cider vinegar, wine, beer, simple syrup, and then the 20% sugar solution. The results were mostly consistent with what was expected considering what compounds fruit flies are attracted to. The results were able to demonstrate what household items prove most effective in attracting fruit flies in order to remove the pests from wherever it is needed. Additional research could look into the attractiveness of each of the active chemicals fruit flies are attracted to, and also find what concentrations and mixtures of these are most attractive to better make a bait for the flies
Attractiveness of Solenopsis Ants (Hymenoptera: Formicidae) to Assorted Sugars and Oils
No full textFire ants (Solenopsis spp.) are bothersome insects to both humans and the environment alike. Due to their prevalence in areas near human habitation, we sought to determine a substance that the ants find attractive that could be used in future control methods. To answer our question, we designed a simple experiment in which Solenopsis sp. specimens were each given the opportunity to choose from a variety of sugars and oils that were presented on a piece of paper in front of them. It was determined that fire ants have a stronger attraction to substances higher in fatty acids, such as cooking oils, than carbohydrates. These results have shown that when devising a home remedy for controlling these insects, individuals would have the most success if they were to use an oil-based product in their control method
Leaf-cutter ants (Genus: Atta) preference for leaves treated with secondary compounds in mid-elevation rainforest
No full textComparison of Resistant and Susceptible Cowpea Plants to Cowpea Aphid (Koch) (Hemiptera: Aphididae)
No full textAphids are one of the most devastating agricultural pests to multiple plants. Plant transformations are being considered as a population control method. This long-term research aims to characterize the molecular mechanism underlying plant-aphid interaction between the cowpea plant and the cowpea aphid. A resistant cowpea line (IT98K-205-8) and a susceptible cowpea line (IT98K-589-2) were observed to analyze how effective a resistant cowpea is in comparison to a susceptible one. Each line was planted, analyzed and scored. Both lines, resistant and susceptible resulted in significantly different results in both room 127 and room 124. Line 205 showed a lower population of aphids starting at day one while line 589-2 population began to decrease on the third day. As seen in this experiment, the overall result was that the resistant line was significantly lower in progeny production than that of the susceptible plant. The survival of the aphid population also decreased on each leaf from day one. Resistant cowpea plants are potential to reducing the aphid population. Additional research should go into manufacture of cowpea plants that are resistant to aphids to benefit crop production for farmers around the world