Browsing by Author "Weaver, Michael John"

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    Bed Bug Management in Low-Income, Multi-Unit Housing: An Evaluation of Resident Education and Cost-Effective, Minimally Toxic Suppression Methods
    Stedfast, Molly Logan (Virginia Tech, 2014-06-10)
    In the United States, we have been battling the bed bug (Cimex lectularius L.) resurgence for over ten years. Current treatment methods are labor intensive, time consuming, and very expensive. Many studies have evaluated the efficacy of treatment methods, but few have focused on bed bug suppression in multi-unit housing. Low income, multi-unit housing residents lack basic bed bug knowledge and are particulary vulnerable to bed bug infestations because they are unable to afford conventional treatment. In this study, diatomaceous earth (D.E.), an inexpensive desiccant dust labeled for bed bug control, was evaluated for its efficacy in killing bed bugs, and determined to be successful. A proactive bed bug suppression program that included D.E. was implemented in a low-income housing facility in Harrisonburg, VA. The program consisted of inexpensive, low toxicity, integrated bed bug management methods, including a novel strategy for applying a perimeter barrier of D.E. in apartment units (n = 121). Over the course of one year, both the number of initial infestations and the costs associated with bed bug treatments were reduced. Low-income, multi-unit housing residents (n = 479) from three cities (Harrisonburg and Richmond, VA; New Orleans, LA) were surveyed before and after an educational seminar to assess their bed bug. After attending the seminar, residents (n = 112) significantly improved (P < 0.0001) their bed bug knowledge, and were able to correctly answer more bed bug-related questions than they had before the educational seminar.
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    Comparing University Entomology Outreach Events While Examining Public Views of Arthropods and Pesticides
    Blevins, Stephanie Lynn (Virginia Tech, 2018-10-12)
    Hokie BugFest is an annual free event designed by the Entomology Department at Virginia Tech to translate the importance of entomology to the public. The event has grown from 2,000 attendees in 2011 to over 8,000 attendees in 2017. Entomology faculty, staff, graduate students and alumni partner with Virginia Cooperative Extension, Virginia 4-H, and other entities to provide an educational experience to the public. The goal of this outreach event is to showcase entomological research, increase public awareness, elevate the appreciation of entomology, develop better public perceptions of insects and other arthropods, and educate participants about pesticide safety and pest management practices. Although many institutions host entomology outreach events like Hokie BugFest (Frazier, 2002; Hamm and Rayor, 2007; Hvenegaard et al., 2013), little research has been conducted to compare the impact of these activities. Whether these events impact public attitudes toward insects and other arthropods is also lacking (Pitt and Shockley, 2014). Several studies have been conducted in other states to investigate public attitudes toward arthropods and pesticides (Baldwin et al., 2008; Byrne et al., 1984; Frankie and Levenson, 1978; Hahn and Ascerno, 1991; Potter and Bessin, 1998); however, research is missing in Virginia. In order to contribute to this literature, three surveys were developed. One survey focused on investigating entomology outreach events similar to Hokie BugFest. Results revealed that event structure, attendance, funding sources, and popular exhibits impact the hosting institution and the surrounding communities. The other two surveys focused on gauging the impacts Hokie BugFest has on youth and adult attendees. Results indicated the event has a positive impact on attendee perceptions of insects, other arthropods, and pesticides.
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    Environmental Influences on Subterranean Termite Foraging Behavior and Bait Acceptance
    Swoboda, Lois Elizabeth (Virginia Tech, 2004-02-25)
    Reticulitermids were significantly more likely to discover subterranean baits connected by physical guidelines than freestanding baits under both laboratory and field conditions. In the laboratory, subterranean termites built significantly longer tunnels adjacent to cellulosic guidelines than plastic guidelines. In the field, all guideline materials were equally effective at directing tunneling activity. Reticulitermes spp. workers were tested to determine their preferred substrate temperature. The preferred range for Reticulitermes spp. workers was found to be 18 to 27 degrees C. A laboratory bioassay was performed to determine if Reticulitermes spp. aggregates within thermal shadows. Significantly more Reticulitermes spp. workers aggregated within cool thermal shadows than control areas. In a multiple choice bioassay, mean consumption was higher for paper baits treated with fructose, galactose, glucose, raffinose, sucrose, trehalose and uric acid than for control baits. In a multiple choice bioassay, mean consumption was significantly lower for baits treated with arbutin, and most amino acids than for control baits. In the no-choice bioassay, the amount of paper bait consumed did not differ significantly for any of the treated baits tested and control baits.
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    The etiology of the decline of eastern white pine (Pinus strobus L.) on Virginia landscapes: a survey of stress factors
    Weaver, Michael John (Virginia Polytechnic Institute and State University, 1982)
    A decline of eastern white pine, Pinus strobus L., has been observed for over 80 years in the eastern United States. The syndrome has not always been discussed as a decline but reported under a variety of names. Symptoms vary with time required for trees to die, but generally include chlorotic foliage, in many cases needle loss producing a tufted appearance, premature annual loss of needles, drooping of needles in some cases, shriveling of bark after a period of time, and eventual death after a period of months to years. An investigation into the causes of decline on landscape sites in Virginia included an indexing technique to compile and analyze, systematically, pertinent data from good and poor quality sites. Over 300 variables were studied from over 100 observations to narrow down the apparent causal factors for future investigation in a controlled environment. Observations were organized into two groups for analysis, one called the “decline habitat” and the other the “natural habitat”. Natural habitat observations consisted of trees from a site in the Jefferson National Forest (VA) and decline habitat observations consisted of trees from mostly western Virginia landscapes. After thorough study for a period of two years, a group of growth indicators were weighed against a group of site quality indicators. Growth quality indicators included: a height vs. age index, a 10-year compilation of tree ring increments and inter-branch whorl measurements converted to percent growth per year, and seasonal foliar color changes using a Munsell rating index. Site quality indicators centered around the soils with soil pH, clay content, amounts of compaction and soil disturbance as the most prominent factors derived from the study. Soil pH averaged 6.95 with a range of 5.9-8.1 for decline habitats; while the pH averaged 5.50 with a range of 5.0-6.0 for the natural habitat. Clay content averaged 37.05% for decline sites vs. 17.76% for the natural site for soils above and in the root zones of white pines. Clay content averaged 43.99% for decline sites vs. 17.95% for the natural site for soils beneath the root zones of white pines. Soils under decline habitat trees were highly compacted with measurements as high as 1806.1 psi to penetrate some decline habitat soils, while the natural habitat soils had little if any compaction, with readings of between 138 and 273 psi. Soil disturbance was not present in the natural site while present in most decline sites. The major cause of disturbance was construction and earth-moving activities around landscape sites. Important abiotic factors which worked in concert with soil factors included poor planting practices, competition with tree feeder roots from turfgrass, chemical pollutants, and mechanical damage by weather and man. Biotic factors were viewed as secondary agents attracted to already weakened trees after initiation of decline by the previously discussed factors. Separate studies of seasonal foliar color changes and the initial finding of the pinewood nematode in Virginia aided in identifying additional indicators of and contributors to decline.
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    Fine Tuning a Sprayer with "Ounce" Calibration Method
    Grisso, Robert D.; Weaver, Michael John; Bradley, Kevin Wayne; Hagood, Edward S.; Wilson, Henry P. (Virginia Cooperative Extension, 2009-05-01)
    Guidelines to quickly evaluate the performance of a sprayer. Sprayer calibration, nozzle discharge, spray pattern uniformity, speed checks, pump performance and plumbing arrangements are evaluated with minimal calculations.
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    Fine tuning a sprayer with ounce calibration method
    Grisso, Robert D.; Weaver, Michael John; Bradley, Kevin Wayne; Hagood, Edward S.; Wilson, Henry P. (Virginia Cooperative Extension, 2001)
    This extension publication discusses guidelines to quickly evaluate the performance of a sprayer. Sprayer calibration, nozzle discharge, spray pattern uniformity, speed checks, pump performance and plumbing arrangements are evaluated with minimal calculations.
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    Historical Use of Lead Arsenate and Survey of Soil Residues in Former Apple Orchards in Virginia
    Schooley, Therese Nowak (Virginia Tech, 2006-05-04)
    Inorganic pesticides including natural chemicals such as arsenic, copper, lead, and sulfur have been used extensively to control pests in agriculture. Lead arsenate (PbHAsO4) was first used in apple orchards in the late 1890's to combat the codling moth, Cydia pomonella (Linnaeus). The affordable and persistent pesticide was applied in ever increasing amounts for the next half century. The persistence in the environment in addition to the heavy applications during the early 1900's may have led to many of the current and former orchards in this country being contaminated. In this study, soil samples were taken from several apple orchards across the state, ranging from Southwest to Northern Virginia and were analyzed for arsenic and lead. Based on naturally occurring background levels and standards set by other states, two orchards sampled in this study were found to have very high levels of arsenic and lead in the soil, Snead Farm and Mint Spring Recreational Park. Average arsenic levels at Mint Spring Recreational Park and Snead Farm were found to be 65.2 ppm and 107.6 ppm, respectively. Average lead levels were found to be 354.5 ppm and 442.3 ppm, respectively. Based on these results, Virginia needs to look at setting standards for lead and arsenic in soil to determine if cleanup of former agricultural lands will be necessary.
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    Introduction, regulations and basic information for safe and effective use of agricultural pesticides
    Weaver, Michael John (Virginia Cooperative Extension Service, 1988-01)
    Your 1988-89 VIRGINIA PEST MANAGEMENT GUIDE outlines the latest recommendations for control of diseases, insects and weeds. The recommendations in each Pest Management Guide are based on investigations carried out by the Research and Extension Divisions of Virginia Polytechnic Institute and State University, in cooperation with other land grant universities, the USDA, and with the agricultural chemical industry.
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    Plumbing systems of agricultural sprayers
    Grisso, Robert D.; Weaver, Michael John; Bradley, Kevin Wayne; Hagood, Edward S.; Wilson, Henry P. (Virginia Cooperative Extension, 2009-05-01)
    Care and operation of different varieties of the plumbing systems of agricultural sprayers.
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    Plumbing systems of agricultural sprayers
    Grisso, Robert D.; Weaver, Michael John; Bradley, Kevin Wayne; Hagood, Edward S.; Wilson, Henry P. (Virginia Cooperative Extension, 2001)
    The plumbing systems of agricultural sprayers are usually considered foolproof. Sprayer problems may occur if plumbing and/or modifications are improperly done or maintenance is ignored. Retrofitting, addition of electrical control systems, and replacement of pumps or nozzles require proper knowledge of the plumbing system and the implications of these changes to sprayer performance. Routine maintenance of the plumbing system is essential.
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    Spatial factors affecting white grub presence and abundance in golf course turf
    Dimock, William John (Virginia Tech, 2004-04-27)
    A regional IPM project was initiated with four rounds of sampling for white grubs on the fairways of nine golf courses located on the Lower Peninsula of eastern Virginia, from 2000 through 2002. Fifteen regressor variables were collected and measured that included local-scale variables, golf course management practices and spatial pattern metrics derived from satellite images that underwent two methods of a supervised classification of six land-cover types (turf, woods, wetland, urban, bare soil and water) on four landscape scales derived from 10 km x 10 km buffer zones surrounding each golf course. Pearson's correlation coefficients were calculated to reduce the number of variables to a few that were highly correlated with white grub densities. Mallow's C(p) calculations were performed on the reduced variable sets to extract those that would be highly predictive. A multiple linear regression was performed using the Mallow's variables to develop eight regression equations (two classification methods x four landscape scales) that were used to predict regional white grub presence and abundance in 2003 on six additional golf courses located on the Lower Peninsula. The best model was the 6 km x 6 km buffer zones model from the second classification method, which included one local-scale variable (golf course age) and three spatial pattern metrics (total turf area, total turf area-to-total urban area ratio, and a woods interspersion-juxtaposition index). The mean difference between actual and predicted values was -0.15, standard deviation = 0.79, R2 = 81.38%. Additionally, a study was conducted to determine whether the number of white grubs collected from transects of sampled golf course fairways was significantly different from those found in the roughs. White grub counts from the roughs were significantly higher (mean = 0.283 grubs/transect, standard error = 0.0135) than those from fairways (mean = 0.146 grubs/transect, standard error = 0.0188); t = -4.31, df = 735, P = 0.0001.
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    Toxicological Analysis of the Neonicotinoid Insecticide Imidacloprid to  Honey Bees, Apis mellifera, of Different Colonies
    Langberg, Kurt (Virginia Tech, 2016-10-14)
    The honey bee, Apis mellifera, provides about $15 billion USD in crop value each year in the U.S. alone in the form of pollination services. Since 2006, commercial beekeepers have reported an average annual overwintering loss of about 28.6% of all managed colonies. There are many factors that are thought to contribute to colony loss including bee-specific pests (e.g. the Varroa destructor mite), bee-specific pathogens (e.g. Nosema fungus), modern beekeeping practices, diminished genetic variability, poor queens, climate change, and exposure to agricultural pesticides. While not the single cause of colony loss, the neonicotinoid insecticides elicit sublethal effects to honey bees that could increase their sensitivities to other stressors that affect colony health. Previous studies found that honey bees have differential sensitivities to the neonicotinoid insecticide imidacloprid, which suggest a mechanism of tolerance to the insecticide in certain colonies. In this study, I examined the imidacloprid sensitivity of honey bees collected from different colonies. After determining a range of LC50 values in the tested colonies, I examined the metabolic detoxification activities of honey bees collected from two colonies that represented the highest and lowest LC50 values, between which there was a 36-fold difference in their LC50 values. I discovered that of the three main families of metabolic detoxification enzymes, general esterases, cytochrome P450 monooxygenases, and glutathione S-transferases (GSTs), a reduction of GST activity with diethyl maleate (DEM) significantly increased imidacloprid-mediated mortality to the honey bees. A comparative analysis of GST kinetic activity from imidacloprid-susceptible and -insensitive honey bees revealed a lower bimolecular inhibition rate constant (ki) for imidacloprid-insensitive individuals (5.07 ± 0.098 nmol/min/mg protein) compared to the imidacloprid-sensitive honey bees (17.23 ± 1.235 nmol/min/mg protein). The IC50 of DEM estimated for bees from each colony showed that the imidacloprid-susceptible honey bees possess a higher IC50 (10 μM) than that of the tolerant honey bees (3 μM). These data suggest that the GSTs in the imidacloprid-tolerant honey bees might be a more efficient detoxification mechanism for the conjugation and elimination of imidacloprid, or imidacloprid metabolites, compared to that of imidacloprid-susceptible honey bees. Therefore, I hypothesize that the differences in metabolic detoxification enzyme activities of honey bees collected from different colonies can result in the differential toxicities of honey bees exposed to neonicotinoid insecticides, such as imidacloprid. However, a thorough examination of imidacloprid detoxification in honey bees is warranted to confirm this hypothesis.