Life Sciences Commons^™

Rnai-Mediated Gene Silencing In The Exotic Redbay Ambrosia Beetle, Xyleborus Glabratus, And Insect-Fungal Interactions Within The Laurel Wilt Complex, Morgan Christine Knutsen

Theses and Dissertations--Entomology

Laurel wilt disease (LWD) is a lethal vascular disease impacting lauraceous hosts caused by Harringtonia lauricola, the fungal symbiont of the redbay ambrosia beetle (Xyleborus glabratus Eichoff) (RAB) (Coleoptera: Curculionidae). LWD has caused tree mortality throughout the southeastern United States and is continuing to spread into new regions. Current management methods have not been successful in preventing spread, warranting investigation into innovative techniques including RNA interference (RNAi).

Elongation factor-1 alpha (ef1a) and actin (act) were established as stably expressed reference genes after exposing beetles to different photoperiod, temperature, and dsRNA exposure. After RAB oral …

Linking Previous Experiences To Behavior And Health In The Honey Bee (Apis Mellifera), Rebecca R. Westwick

Theses and Dissertations--Entomology

An organism’s ability to respond to changing conditions can be vital to its success. Indeed, plasticity is a common feature of living organisms. Much of the research in this area, though, has focused on effects caused by environmental conditions. What has received relatively less attention is how social experiences and broader features of an organism’s social environment can lead to long-lasting changes in health and behavior. This knowledge gap exists despite the well-documented existence of health and behavioral effects after social interactions in certain taxa such as humans.

Social insects such as honey bees provide an excellent opportunity to better …

Ecological Risk Assessment Of Transgenic Conditional Lethality Systems For Genetic Biocontrol Strategies, Fernan Rodrigo Perez-Galvez

Theses and Dissertations--Entomology

Genetic strategies of insect pest control are receiving increased interest due to recent advances in genetic engineering. By introducing alleles that make males functionally sterile, genetically modified (GM) insects can be used in area-wide pest management programs similar to the Sterile Insect Technique (SIT). Genetic control strategies carry several potential benefits, including improved efficacy and specificity, lower operation costs, and reduced dependence on chemical insecticides, but their use is still controversial despite extensive technical documentation indicating their innocuity to humans and the environment. This hesitation is likely due to the novel nature of the approach.

While the first field applications …

Costs And Benefits Of Integrating Poultry Into Cover Crop - Vegetable Rotations, Viktor Halmos

Theses and Dissertations--Entomology

Integrated livestock systems were once common leading up to the 20th century where livestock generated manure that was then used to fertilizer crop production in a closed- or semi-closed system. However, with the industrialization of agriculture in the mid to late 20th century, specialization drove simplified systems that segregated livestock from cropping systems. This segregation led to nutrient surpluses occurring in livestock operations, and nutrient demands in cropping systems creating a plethora of environmental issues. With the increased awareness of environmental issues, a renewed interest in integration has driven producers and researchers to experiment with integration again. For research, the …

Surveillance For Ticks And Tick-Borne Pathogens In Kentucky, Anna Rosalee Pasternak

Theses and Dissertations--Entomology

Tick-borne diseases are an emerging threat to human and animal health. In Kentucky, tick-borne disease surveillance has identified rising incidences of spotted fever rickettsiosis, ehrlichiosis, and Lyme disease. Since these diseases occur through the bites of infected ticks, effective prevention efforts are reliant upon knowing where the risk of exposure to tick bites exists. Historical data on tick distribution in Kentucky is variable, with very little reported on a statewide scale, leaving vector control workers, public health personnel, physicians, veterinarians, and others to rely on outdated, intermittent, or out-of-state information. In my dissertation, I surveyed ticks and select tick-borne pathogens …

Managing Death In Termites, Jizhe Shi

Theses and Dissertations--Entomology

Death of individuals from the same species represents potential risks from disease, predation or competition for animals. Diverse responses associated with death have evolved ranging from simply avoiding or being attracted to the corpses in solitary animals to complicated undertaking behavioral repertoire in eusocial insects. A systematic review in chapter 1 suggested cannibalism is an ancestral and widespread death-related behavior in all non-human animals. Termites are suggested to switch their undertaking behavioral responses from cannibalism to burial based on interactions between chemicals associated with death to balance risks and benefits associated with decomposition. In eusocial animals like termites with caste …

Understanding The Effects Of Age, Environmental Conditions, And Placement On Cockroach Gel Bait Performance, Isabelle Lucero

Theses and Dissertations--Entomology

Cockroach baits are one of the most effective tools used for German cockroach (Blattella germanica L.) control. This is due in part to the number of cockroach baits on the market with various matrix compositions and active ingredients, aiding in the control of resistant (physiologically and behaviorally) cockroach populations through bait rotation. However, it remains unclear how cockroach gel baits perform over time and under different environmental conditions. Therefore, we aged six cockroach gel baits for varying times (24 hours, one month, three months, six months) and at three relative humidities (15%, 40%, and 80%), and tested their performance …

Net Effects Of Wild And Managed Birds In Agroecosystems, Karina Garcia

Theses and Dissertations--Entomology

Agricultural intensification and expansion have reduced biodiversity in agroecosystems, jeopardizing the ecosystem services that nature provides to humans in these landscapes including wildlife-mediated pest control. Among these purveyors of ecosystem services are birds, who can provide services to agroecosystems by consuming arthropod pests. Yet some bird species also act as pests by consuming crops. Herein, I use molecular diet analysis through high-throughput sequencing on DNA extracted from bird fecal samples to examine birds’ diet and classify bird species as consumers of major strawberry pests (Lygus spp.). Additionally, I use targeted PCR approaches to determine which bird species consumed strawberries. …

A Functional Genomics Approach To Overwintering Mechanisms In Insects, Emily Allison Wheeler Nadeau

Theses and Dissertations--Entomology

Insects living in temperate and polar environments have developed numerous adaptations to increase survival at low temperatures. A majority of insects are freeze-intolerant and die from internal ice formation, but some are freeze-tolerant and can survive ice formation in extracellular spaces. Both categories of insects prepare for winter with a combination of seasonal and rapid acclimation responses, which differ both in time course and in underlying mechanisms. In this dissertation, I examine adaptations for winter survival in several insect species with a specific focus on molecular mechanisms. To better understand the underpinning mechanisms of these adaptations, I leverage functional genomics …

Effects Of Physiological Stage And Diet On Drosophila Suzukii Olfaction, Aerianna Shindindowi Littler

Theses and Dissertations--Entomology

Massive economic damage by spotted-wing drosophila (SWD), Drosophila suzukii, results from their unique egg laying behavior. Gravid SWD flies employ a complex suite of behaviors to find fruit with the optimum firmness and chemistry. We tested for SWD attraction to various fruits and found overripe raspberries to be most attractive to gravid flies which was unexpected since they oviposit in ripe fruit. We next tested the same choice assay in a T-maze and found that the results were comparable. We also found discrete odor profiles among the ripening stages. When testing for sugars and CO2 concentrations from field-collections, overripe …

Gene Silencing Provides Insights Into Bark Beetle Biology And Creates Potential For Broad Scale Forest Protection, Beth R. Kyre

Theses and Dissertations--Entomology

Dendroctonus bark beetles are among the most economically and ecologically significant forest pests in North America and play a critical role in the overall health of conifer forest ecosystems. Dendroctonus bark beetles influence ecosystem benefits and biodiversity and drive forest succession, and adversely affect timber production, forest management, and recreation. As temperatures surge and climatic fluctuations become more extreme, catastrophic bark beetle outbreaks are increasing in frequency, escalating pressures on highly vulnerable conifer forests already compromised by heat and drought. Eruptive outbreaks of Dendroctonus beetles are largely unhindered by traditional silvicultural management; these practices further disrupt forest ecosystem services, including …

Rna Interference For Emerald Ash Borer Suppression: Ecotoxicological Assessment And Delivery Methods, Flavia Pampolini

Theses and Dissertations--Entomology

The emerald ash borer (EAB), Agrilus planipennis (Coleoptera: Buprestidae), is a highly invasive phloem-feeding insect native to Asia. It has killed millions of ash trees (Fraxinus spp.) since its accidental introduction into North America, causing profound economic and ecological impacts. RNA interference (RNAi) or double-stranded RNA (dsRNA)-mediated gene silencing is an emerging biotechnology that is developing as an innovative tool for pest management. Exogenous dsRNA triggers the RNAi pathway, silences genes, and disrupts protein function, causing insect mortality. RNAi has proven effective in reducing target gene expression and causing mortality in EAB; however, two aspects stand as barriers …

Southern Pine Beetle-Specific Rna Interference Demonstrates No Effects On Nontarget Insects, Hannah Marie Hollowell

Theses and Dissertations--Entomology

The endemic southern pine beetle (SPB), Dendroctonus frontalis Zimmermann, is a highly destructive bark beetle that has devastated coniferous forests of the southern United States for decades. Traditional management strategies have been unable to respond effectively to largescale SPB outbreaks, prompting exploration of novel techniques including RNA interference (RNAi). Double-stranded RNAs (dsRNAs) are effective at triggering gene silencing and inducing mortality in SPB, but determining delivery methods and demonstrating specificity of the treatments is necessary before this technology may progress to deployment.

I evaluated three SPB-specific dsRNAs on model nontarget insects to assess potential lethal effects, sublethal effects such as …

Distribution And Diversity Of Heliothine And Other Lepidopteran Nudiviruses, Emrah Ozel

Theses and Dissertations--Entomology

Helicoverpa zea nudivirus 2 (HzNV-2) is the only known sterilizing and sexually-transmitted insect virus and causes pathological symptoms in H. zea reproductive tissues. HzNV-2 has features that make it a candidate as a H. zea (corn earworm) control agent, such as the ability to cause asymptomatic (latent) and symptomatic (lytic) infections and the ability to influence mating behavior of its host to favor virus spread. HzNV pathology has been studied and its genome sequenced, however, its prevalence in natural populations is largely unknown. In this study, we developed and used a low-cost PCR-based molecular survey to investigate HzNV-2 prevalence and …

Optimizing Monarch Butterfly And Bee Conservation Efforts In The Urban Landscape, Adam M. Baker

Theses and Dissertations--Entomology

The eastern migratory population of monarch butterflies (Danaus plexippus) is in serious decline. Most of the efforts to conserve this iconic insect focus on habitat restoration in the US Midwest. Often overlooked are small butterfly-centric gardens that can act as stepping stones between urban and rural areas. These studies aim to optimize the conservation value of such gardens.

Eight milkweed (Asclepias) species varying in height, form, and leaf shape were compared over two years in a common-garden experiment. I measured milkweed growth, rhizome spread, and bloom periods, conducted bi-weekly counts of monarch eggs and larvae, evaluated …

Epigenetic Regulation Of Hormone Action In The Red Flour Beetle, Tribolium Castaneum (Herbst), Smitha George

Theses and Dissertations--Entomology

Hormones are the chemical communication signaling molecules released into the body fluid to stimulate target cells of multicellular organisms. Two major hormones, ecdysteroids (20-hydroxyecdysone, 20E) and juvenile hormones (JH), regulate a wide variety of physiological and developmental processes in insects. Therefore, hormones have been extensively studied and are attractive targets for the development of target-specific insect control methods. Recent studies suggest that epigenetics adds another layer of regulation to explain multiple functions of the same circulating hormone in different tissues and at various time points. In my dissertation, I focused on a major post-translational modification, ‘acetylation,’ to elucidate the epigenetic …

Aggregation Behavior In The Bed Bug, Cimex Lectularius L., Paul D. Baker

Theses and Dissertations--Entomology

The bed bug, Cimex lectularius L., is a common household pest that feeds on the blood of its human hosts. Unlike many other hematophagic arthropods, bed bugs have not demonstrated the ability to vector disease; yet its presence in a household often leads to fear and anxiety amongst its human host victims. Bed bugs spend the majority of their time aggregating in enclosed and hidden locations, making it difficult to detect and eradicate them. One of the significant mediators of aggregation behavior is an aggregation pheromone. The pheromone has been identified to be six chemical compounds, five volatile compounds that …

Emerald Ash Borer Development Across A Latitudinal Gradient: Implications For Biocontrol, Sarah Pellecchia

Theses and Dissertations--Entomology

Emerald ash borer, EAB, (Agrilus planipennis Fairmaire) is an invasive beetle that kills ash trees. It was accidentally introduced from China, and has rapidly expanded across North America, now occupying much of the eastern US. Four classical biocontrol parasitoids have been released to help mitigate its spread and impact: Tetrastichus planipennisi Yang, Spathius agrili Yang, S. galinae Belokobylskij and Strazanac, and Oobius agrili Zhang and Huang. These parasitoids have been deployed throughout EAB’s invaded range, but there has been limited recovery of the parasitoids from their release sites in southern states. I evaluated whether this lack of establishment might …

Dynamic Balancing Of Foraging And Defensive Effort Contribute To The Optimality Of The Honey Bee Robbing Strategy, Grayson James Grume

Theses and Dissertations--Entomology

The optimality of a foraging strategy shifts in response to dynamic ecological conditions and the need to devote effort to other tasks. Nest defense and foraging effort in the honey bee may trade off as both tasks are performed by a shared workforce of physiologically-specialized individuals in exclusive roles. Honey robbing is a foraging strategy predicted to benefit from simultaneous increases in foraging and defensive effort, but may be constrained by workforce specialization. We developed a methodology to induce robbing behaviors with uninhabited bait hives. We used this methodology to evaluate foraging and defensive effort before and during robbing by …

Developing Alternative Practices For Management Of Flea Beetles Attacking Eggplant And Leafy Brassicaceous Greens, Robert Brockman

Theses and Dissertations--Entomology

Flea beetles are a challenging pest for many producers of vegetable crops in Kentucky. Chewing numerous small holes in the leaves of their host plants, high flea beetle populations can quickly overwhelm unestablished crops. I tested the efficacy of several alternatives to insecticides within brassicaceous leafy greens and eggplant. Four field trials in 2019 and 2020 compared essential oil sprays, the woven-mesh row cover ProtekNet, the spunbonded row cover Agribon, and reflective silver mulch to an untreated control, a conventional insecticide rotation of dinotefuran and pyrethroids, and an organic insecticide rotation of spinosad and pyrethrins. The silver reflective mulch was …

Identification And Characterization Of Epigenetic Regulators In The Yellow Fever Mosquito, Aedes Aegypti, Shankar C. R. R. Chereddy

Theses and Dissertations--Entomology

Due to the increased interactions between the sylvatic and urban cycles of Aedes aegypti life cycle, there has been an increase in the incidence of vector-borne diseases. The risk involved through the transmission of viruses like Dengue, Zika, Yellow-fever and Chikungunya calls for an effective control method for the deadly vector. The possibility of pesticide resistance and the costs involved in producing new pesticides have pushed Sterile Insect Technique (SIT) into prominence. However, current methods used to sterize insects for SIT are not highly efficient. This study tackles current issues in mosquito control by identifying and characterizing epigenetic regulators that …

Physiological Ecology Of Overwintering And Cold-Adapted Arthropods, Leslie Jean Potts

Theses and Dissertations--Entomology

Given their abundance and diversity, arthropods are an excellent system to investigate biological responses to winter. Winter conditions are being majorly impacted by climate change, and therefore understanding the overwintering biology of arthropods is critical for predicting ecological responses to climate change. In Chapters 2 and 3, I investigate the winter biology of a winter-active wolf spider. I show that winter-active spiders can take advantage of periodic prey resources and grown in the winter, which may allow them to get a jumpstart on spring reproduction. I also investigate spiders’ ability to track changes in their environment by quantifying low temperature …

A Tangled Web: The Dynamics Of Endosymbiotic Infections In A Linyphiid Spider, Laura Cecilia Rosenwald

Theses and Dissertations--Entomology

Many arthropods are infected with bacterial endosymbionts that manipulate host reproduction, but few bacterial taxa have been shown to cause such manipulations. Mermessus fradeorum (Linyphiidae) is a sheet-weaving spider that displays both feminization and cytoplasmic incompatibility (CI). To correlate reproductive manipulations to endosymbionts, I surveyed the bacterial community of M. fradeorum using high throughput sequencing and found that individuals can be infected with up to five different strains of bacteria from the genera Wolbachia, Rickettsia, and Rickettsiella. Rickettsiella was found in all 23 tested spider matrilines. I used antibiotic curing to generate uninfected matrilines that I reciprocally crossed with …

Management Of Stink Bugs (Hemiptera: Pentatomidae) On Soybean In Kentucky, Yaziri Gonzalez

Theses and Dissertations--Entomology

Phytophagous stink bugs (Hemiptera: Pentatomidae) are pests of significant importance to soybean, Glycine max (L.), because they can cause severe losses in seed quality, ultimately affecting yield. Damage to soybean is caused through a process called extra-oral digestion. This occurs when the adults and nymphs of stink bugs pierce plant tissues with their mandibular and maxillary stylets, insert digestive enzymes, break down tissue, and extract the digested plant fluid. Three endemic stink bug species of North America are present in Kentucky: green stink bug (Chinavia hilaris), brown stink bugs (Euschistus species complex), and red-shouldered stink bug (Thyanta custator) …

Management Of Sugarcane Aphid (Melanaphis Sacchari) Using Biological And Cultural Tactics In Kentucky, Nathan Harriman Mercer

Theses and Dissertations--Entomology

In 2013, a new aphid pest of sorghum, the sugarcane aphid Melanaphis sacchari Zehntner (Hemiptera: Aphididae), was found in the southern US, and caused significant yield loss in sorghum. Since then, M. sacchari has spread to most of the sorghum growing regions. Unmanaged populations can cause complete crop loss in grain, forage and sweet sorghum. M. sacchari cannot survive winters without a live plant tissue and must recolonize much of its pest range annually. Sweet sorghum (Sorghum bicolor) is an important crop for many growers in Kentucky, producing $16-25 million a year from its syrup. Biological control of …

Biology And Management Of The Soybean Stem Borer, Dectes Texanus Leconte, In Kentucky, Izabela Gomes

Theses and Dissertations--Entomology

Dectes texanus LeConte (Coleoptera: Cerambycidae) is a longhorn beetle species endemic to eastern United States. Originally described as a pest of weeds from the family Asteraceae, D. texanus has expanded its host range and is found infesting the stems of soybeans, Glycine max (L.) through the southwestern and middle United States. Female D. texanus chews a hole in the epidermis of a petiole and oviposits on it. Then, the D. texanus larva depletes all the pith of the stem making a tunnel down to the base of the plant and girdle the stem about 5 cm above the …

The Mechanism Of Rna Interference In Arthropods, June-Sun Yoon

Theses and Dissertations--Entomology

RNA interference (RNAi) is a useful reverse genetics tool for investigation of gene function as well as for practical applications in many fields including medicine and agriculture. Due to the variability in RNAi efficiency, RNAi-based methods are currently being developed for controlling only coleopteran insects which are known to be amenable to RNAi. The first chapter of my thesis includes findings from research to investigate what are the factors that make coleopteran insects relatively more efficient in RNAi. I used Colorado potato beetle (CPB), Leptinotarsa decemlineata and its cell line (Lepd-SL1) as study models to identify genes that play key …

Emerald Ash Borer (Coleoptera: Buprestidae) Host Expansion; Trading An Optimal Host For Enemy Free Space?, David G. Olson

Theses and Dissertations--Entomology

Emerald ash borer (EAB), Agrilus planipennis (Coleoptera: Buprestidae), is an aggressive invader from Asia that has killed millions of trees in North America. Recently EAB has been documented developing in a novel host, white fringetree, Chionanthus virginicus. I evaluated larval performance in two common ash species and white fringetree by infesting excised bolts with emerald ash borer eggs. In addition I evaluated several plant characteristics to determine which most influence larval development. I also conducted choice and no choice assays using the classical biological control agent, Tetrastichus planipennisi (Hymenoptera: Eulophidae), to assess its ability to locate larval EAB in …

Dna Barcoding As A Tool For Species Discovery And Documentation In The Superfamily Ichneumonoidea, Sarah Meierotto

Theses and Dissertations--Entomology

Changes to traditional taxonomic methods to incorporate new technologies and methods have already improved the quality of species hypotheses, but more work can be done to improve the speed of new species documentation. The mitochondrial COI DNA barcode has been successfully used to identify species with high accuracy since the early 2000s, and has been used in conjunction with morphological examinations and other DNA markers to discover and delimit new species. This thesis explores the application of DNA barcodes as the primary data for delimitation and diagnosis of new species of ichneumonoids.

The genera Zelomorpha and Hemichoma are revised and …

Bee Conservation In Urban Landscapes: Assessing Bee Assemblages, Bee–Attractiveness, And Nutritritional Value Of Woody Landscape Plants And Mitigating Potential Bee Hazard From Neonicotinoid Insecticides, Bernadette Maria Mach

Theses and Dissertations--Entomology

Public awareness of declining pollinator populations has increased interest in creating “bee–friendly” urban landscapes. I quantified bee visitation and assemblages of 72 species of flowering woody plants common in urban landscapes. I found strong plant species effects and variation in seasonal activity of particular bee taxa but no overall differences in bee visitation or genus diversity between native versus nonnative species or trees versus shrubs. Analysis of pollen from a subset of these plants revealed small but statistically significant differences in total and essential amino acids between native and nonnative species and trees and shrubs, although each group had species …