Entomology Commons^™

Assessing Integrated Pest Management Protocols For The Invasive Aquatic Weed Giant Salvinia (Salvinia Molesta), Samantha Lee Prinsloo

LSU Doctoral Dissertations

Giant salvinia (Salvinia molesta) is free-floating aquatic fern that originates from South America. Through human introduction, giant salvinia has escaped its native range and is listed as an invasive species across multiple continents causing negative socio-economic and environmental impacts. This research aimed to expand our understanding of integrated pest management for controlling giant salvinia by combining chemical and biological control. The objectives were to assess the effects of rainfastness, carrier volume, and growth stage on herbicide efficacy, assess augmented biological control and optimal weevil release densities, assess weevil populations in the field, determine herbicide and surfactant toxicity to …

Environmental, Social, And Molecular Regulation Of Foraging Behavior In The Formosan Subterranean Termite, Arjun Khadka

LSU Doctoral Dissertations

Foraging is a critical activity in social insects, essential for resource acquisition and colony sustenance. In termites, this behavior is shaped by environmental, social, and genetic factors, yet the underlying regulatory mechanisms remain poorly understood. In this study, we examined how environmental food and moisture availability, and the age of termites affected foraging activities, along with the molecular regulation of foraging in the Formosan subterranean termite, Coptotermes formosanus, using a combination of behavioral assays, transcriptomics, and molecular biology approaches. First, we demonstrate that food and moisture deprivation (FMD) significantly affects foraging, with termites under deprivation conditions exhibiting increased foraging …

Biological Control Of Roseau Cane Scale With Parasitoid Wasps In Louisiana, Tanner C. Sparks

LSU Doctoral Dissertations

Roseau cane scale, Nipponaclerda biwakoensis (Hemiptera: Aclerdidae) is an invasive species of scale insect negatively impacting Phragmites australis (Cyperales: Poaceae) stands within the Mississippi River Delta. The scales were first detected in 2017 from reports of Phragmites die-back within the MRD by landowners. Initial range surveys located RCS infested Phragmites stands were primarily limited to southeastern Louisiana with a single population near Port Arthur, Texas. Follow-up field surveys conducted annually from 2021 to 2023 monitoring further range expansion by the scale show the current range extends nearly 600 km between High Island, Texas and Bayou la Batre, Alabama. Climate matching …

Integrated Pest Management And Behavior Of Stored Grain Beetles, Ethan Doherty

LSU Doctoral Dissertations

The lesser grain borer, Rhyzopertha dominica, and the rice weevil, Sitophilus oryzae, are two of the most destructive pests of stored rice. Their management has relied heavily upon fumigant insecticides. However, amid growing concerns that fumigant-resistant pests are becoming widespread, there is an urgent need for diversified management techniques and integrated pest management. Here, we explored management techniques and the behavior of these beetles. Host plant resistance toward both beetles was evaluated for 13 varieties of rice. We found large differences among varieties for both beetles in all resistance measures. We found that while nutritional components of a …

Morphological And Molecular Characterization Of The Olfactory System In The Formosan Subterranean Termite, Paula Castillo

LSU Doctoral Dissertations

The Formosan subterranean termite, Coptotermes formosanus, is a eusocial insect species. Its members live in colonies consisting of reproductive (queen and king) and non-reproductive individuals (workers and soldiers). Olfaction is an essential sense for the social life of many insects. However, in termites, little is known about how olfactory cues are perceived in the peripheral sensory system (antennae) and processed in the central nervous system (brain) to elicit different behavioral responses across castes. In this study, we investigated the olfactory system in all castes (soldiers, workers, and reproductive alates), from the antennal and brain morphology to the antennal gene …

Evaluating The Pesticide-Induced Outbreak Of Soybean Looper, Chrysodeixis Includens (Walker) (Lepidoptera: Noctuidae), In Louisiana Soybean, Scott Lee

LSU Doctoral Dissertations

Soybean looper, Chrysodeixis includens (Walker), has established itself as the primary lepidopteran defoliator in Midsouth soybean agroecosystems. Pesticide-induced outbreak events associated with this pest have been observed by soybean producers. The insecticides believed to prompt these incidents are routinely used for the control of other co-occuring pests, such as stink bugs. Outbreak conditions present soybean producers with conflicting management decisions for pests. Laboratory, greenhouse, and field experiments were conducted to provide a better understanding of insecticide usage impact on populations of C. includens and the arthropod community. To discern the potential mechanisms behind C. includens outbreak, a baseline for the …

Characterization Of Antiviral Immunity, Host Virus Interactions, And Toxicity Of Agrochemical Residues In The Western Honey Bee, Christopher Fellows

LSU Doctoral Dissertations

Honey bee colonies have perished at an alarming rate for over 15 years. Among the multitude of threats to bee health, virus infections and agrochemical exposure appear to be major drivers of colony loss. As virus infection is among the most damaging influences on bee health, we first investigated a putative target for antiviral immunity, termed K_ATP channels. We previously demonstrated that pharmacologically activating K_ATP channels induces the production of reactive oxygen species and increases survival during infection with Israeli Acute Paralysis Virus. Here, we demonstrate that K_ATP modulation and ROS induction reduce virus replication and enhance …

Defining Understudied Mechanisms Of Potassium Ion Flux In The Insect Nervous System, Rui Chen

LSU Doctoral Dissertations

To identify novel insecticide target sites that can address the evolution of insecticide resistance, our group has tested the insecticidal potential of two potassium flux pathways: potassium-chloride (K+/Cl−) cotransporter (KCC) and inward rectifier potassium (Kir) channels. GABAergic signaling is the cornerstone of fast synaptic inhibition for neural signaling in arthropods; thus, the γ-aminobutyric acid (GABA)-receptor-chloride-channel (GRCC) complex has been a longstanding target for insecticides. Despite the importance to neuronal homeostasis, the upstream mechanisms enabling GRCC function are poorly defined. The data presented in this dissertation provide strong support that KCC is an essential ion transport system for proper neural function …

The Applied Use Of Zein Nanoparticles In Agriculture, Colin Bonser

LSU Doctoral Dissertations

Nanotechnology is a multifaceted and a promising strategy in agricultural pest management for the development of insecticides or insecticide carriers. Research has shown that nanoparticles increase stability and efficacy of entrapped chemical pesticides to prevent active ingredient degradation while improving chemical stability and solubility. The following work evaluated nanoparticles synthesized from biopolymers, materials that originate from renewable sources also have an increased biodegradability.
Work was conducted under laboratory, greenhouse, and field conditions to test the biopoloymers as possible insecticide and insecticide carriers. The primary biopolymer evaluated in the following studies was zein, although lignin and chitosan were also evaluated. Overall, …

Esterase Mediated Insecticide Resistance In The Southern House Mosquito, Culex Quinquefasciatus, Vivek Pokhrel

LSU Doctoral Dissertations

Much is known about the development of insecticide resistance associated with targeted application against insect populations. However, off-target selection by applications of insecticides in agricultural and residential sites also impacts development of insecticide resistance and is understudied. Similarly, the impact of selecting one life stage of mosquitoes on the insecticide susceptibility of different life stages is largely unknown. The first part of this study shows that susceptibility to chlorantraniliprole, which is applied in rice and sugarcane fields in LA, decreased (5.7 to12-fold) in populations of Culex quinquefasciatus collected from near these fields compared to a reference field strain. In addition, …

The Risks Posed By Mosquito Ultra-Low Volume Applications To Procambarus Clarkii Production, Timothy Mcnamara

LSU Doctoral Dissertations

Mosquito abatement has received much scrutiny due to concerns about the impacts of control applications on non-target organisms. In Louisiana, a great deal of this concern has come from crawfish farmers claiming mosquito abatement applications have damaged crawfish production. To determine which mosquito abatement practices and products pose a risk to crawfish production, we conducted a series of studies examining mosquito abatement practices in the vicinity of crawfish production fields and the impacts of common mosquito abatement product exposure on crawfish health and production. We found that mosquito ULV applications are the most likely to result in exposure to crawfish …

Geographical Distribution, Allele Frequency, And Inheritance Of Cry1a.105 And Cry2ab2 Resistance In Helicoverpa Zea In The Southeastern Region Of The United States, Wenbo Yu

LSU Doctoral Dissertations

The corn earworm, Helicoverpa zea (Boddie), is a target pest of Bacillus thuringiensis (Bt) maize and cotton in the U.S. Previous studies have reported that this pest has developed field resistance to pyramided Cry1A/Cry2A maize and cotton in certain areas of the southern United States. The objectives of this study were to 1) determine the current status and distribution of the resistance to Cry1A.105 and Cry2Ab2 in H. zea in the southeastern United States; 2) estimate the resistance allele frequencies to the two Bt proteins in H. zea field populations in the region, and 3) assess the inheritance of the …

Sodium Mediates Developmentally Plastic Responses In Plants And Herbivores, Luis Santiago-Rosario

LSU Doctoral Dissertations

Sodium plays a crucial role in organismal performance, trophic-level interactions, and eco-evolutionary dynamics. For plants, sodium impacts osmoregulation, growth, and water uptake. For animals, sodium is essential influencing osmoregulatory processes, muscle and neural development, and blood regulation. My dissertation aims to disentangle why sodium mismatch affects resource-consumer interactions and its influence on morphological and behavioral plasticity. First, I identified how sodium impacts plant performance and sodium accumulation strategies. I initially focused my research on understanding how increasing substrate sodium affects plant growth and tissue sodium accumulation strategies in controlled settings using a systematic review approach. I found that saltier plants …

Canopy Arthropod Responses To Catastrophic Wind Disturbances In Gulf Coast And Caribbean Forests, Manoj Pandey

LSU Doctoral Dissertations

Hurricanes are major natural disturbances and integral components of forest disturbance regimes globally. The frequency and intensity of hurricanes are predicted to increase in the future due to global warming. The altered hurricane regime, along with direct effects of climate change on arthropod populations and communities, has the capacity to endanger the critical ecosystem processes and services provided by forest canopies. Therefore, it is crucial to understand the responses of forest fauna to disturbances such as hurricanes. This dissertation is aimed at understanding the short-term and long-term effects of hurricanes on canopy arthropods to improve predictions of the consequences of …

Improving The Deployment Of Insecticidal Seed Treatments In Louisiana Rice In Accordance With Integrated Pest Management, Megan Marie Mulcahy

LSU Doctoral Dissertations

Lissorhoptrus oryzophilus Kuschel (Coleoptera: Curculionidae), is the most destructive insect pest of rice in the United States. Lissorhoptrus oryzophilus larvae feed on rice roots, reducing yields by up to 25 %. Lepidopteran stem borers, in the family Crambidae, are also economically important pests of rice in Louisiana.

Currently, insecticidal seed treatments are used throughout the U.S. Mid-south rice industry to prophylactically control L. oryzophilus. Chlorantraniliprole seed treatments are also effective against stem borers. Thus, insecticidal seed treatments are used on >80 % of Louisiana rice acreage. Although seed treatments reduce damage inflicted by these pests, they are applied preventatively …

Investigating Plant Tolerance For The Management Of Insect Pests In Rice, James Michael Villegas

LSU Doctoral Dissertations

The rice water weevil, Lissorhoptrus oryzophilus Kuschel (Coleoptera: Curculionidae), is the most destructive and widespread insect pest of rice (Oryza sativa L., Poaceae) in the USA. This insect poses a global threat to rice production, having invaded rice-producing regions of Asia and Europe. Moreover, lepidopteran stemborers, particularly the invasive Mexican rice borer, Eoreuma loftini (Dyar) (Lepidoptera: Crambidae), are increasingly becoming problematic in Louisiana rice. Although insecticidal seed treatments have been widely used against weevils and stemborers, alternative management strategies are needed. Plants possess defense-related traits that both reduce injury from herbivores (resistance) and the amount of yield loss per …

Characterizing The Epidemiology Of Bluetongue And Epizootic Hemorrhagic Disease Virus In Louisiana, Michael Edward Becker

LSU Doctoral Dissertations

Bluetongue virus (BTV) and Epizootic Hemorrhagic Disease Virus (EHDV) are arthropod-borne viruses (Reoviridae; Orbivirus) transmitted by biting midges in the genus Culicoides. These viruses cause hemorrhagic disease and induce serious morbidity and mortality rates in wild and captive deer. Cattle are normally asymptomatic but serve as the reservoir/amplifying host for these viruses and play an important role in the transmission cycle. The objectives of this study were to characterize the epidemiology of these viruses as they relate to white-tailed deer and cattle, evaluate different trap types for collecting Culicoides midges, and determine if these viruses can be detected …

Taxonomy And Systematics Of The New Zealand Pselaphini (Coleoptera: Staphylinidae: Pselaphinae), Brittany Elin Owens

LSU Doctoral Dissertations

The New Zealand (NZ) Pselaphini was revised at the species level, a phylogenetic analysis was performed using morphological data, and first steps were taken towards the construction of a molecular analysis of the tribe. Eight new genera and 33 new species were discovered from specimens collected from the NZ mainland, offshore islands, Chatham Islands and the Subantarctic Islands. Of the 13 species originally described in the genus Pselaphus by Thomas Broun during the late 19^th and early 20^th centuries, all were either reassigned to the genera Pselaphaulax and Pselaphogenius, or were placed into new genera. Three names …

Effects Of Virus Infection And Volatiles On Aphid Virus Vector Behavior On Sweetpotato, John Lawrence Dryburgh

LSU Doctoral Dissertations

Sweetpotato is affected by a wide variety of viruses worldwide, which can cause yield losses of up to 90%. Many of these viruses are transmitted by aphids in a non-persistent manner. Non-persistent viruses are acquired and transmitted within minutes, and thus conventional control, such as insecticides, are ineffective. Altering aphid movement and feeding behavior may affect the rate of virus transmission. One potential method to alter aphid behavior is volatile organic compounds (VOC), including volatiles emitted by virus infected plants, plant hormones, and commercial control agents. Aphid movement near sweetpotato fields was monitored to determine trends throughout the growing season. …

Effects Of Plant Viruses On Vectors And Non-Vector Herbivores In Three Different Pathosystems, Sunil Paudel

LSU Doctoral Dissertations

Plant viruses are an important component of agro-ecosystems and the knowledge of impacts they can cause on their hosts, and on different vectors and non-vector herbivores associated with the hosts, is very crucial in devising sound management strategies for virus disease and vector control in the landscape. The interactions between these components, however, are difficult to predict and vary according to the system under investigation. In order to understand some of these interrelationships, different sets of experiments were carried out in three different pathosystems to look at the impacts of plant viruses on vector and non-vector herbivores. Firstly, in Sorghum …

The Tripartite Interaction Between Arbuscular Mycorrhizal Fungi, Rice, And Insects, Lina Bernaola Alvarado

LSU Doctoral Dissertations

Losses caused by pests remain an important limitation to achieving high rice yields in the United States. Arbuscular mycorrhizal fungi (AM fungi) are able to modify plant physiology by increasing plant growth or inducing defense responses against insect herbivores. However, studies of the role of AM fungi in agroecological factors, including natural occurrence, plant resistance, soil dependency, and plant tolerance, with specific regards to pests that feed on rice plants have not been conducted before. A three-year study revealed natural occurring colonization by AM fungi on rice roots sampled in four rice-producing areas in the southern United States. Overall, rice-AM …

Intraguild Predation: Interactions Between Predators, Pathogens, And Their Shared Resources In Crop Pest Communities, Andrew Jason Flick

LSU Doctoral Dissertations

Crop pest management requires an understanding of the complex interactions among pest species that potentially damage crop yield and species that may be crucial for controlling pest species outbreaks. For example, predators, parasitoids, and pathogens are constantly interacting via their shared prey or hosts. Predators may prefer infected prey, which can be easier to catch; however, infected prey may be less nutritious or even lethal for predators. These interactions then dictate the short-term dynamics of host and pathogen as well as between prey and predator. "How these dynamics change as the species in the system change either empirically or theoretically?" …

Induced Resistance In Rice, Oryza Sativa, To Herbivores In The Southern United States, Emily Clare Kraus

LSU Doctoral Dissertations

The effects of herbivory and chemical applications as potential inducers of resistance to herbivores in rice, Oryza sativa L., were explored through a series of field, greenhouse, and laboratory experiments. Studies were conducted to investigate the preference and performance of several herbivore pests of rice with a focus on, Lissorhoptrus oryzophilus Kuschel, the rice water weevil (RWW), under conditions where rice plants had been stressed by previous herbivory or chemical applications. The effects of defoliation by Spodoptera frugiperda (J.E. Smith), the fall armyworm, on resistance and tolerance of rice to RWW under field conditions were examined. Herbivory by fall …

Impact Of Temperature, Plant Species, And Sorghum Cultivar On The Population Dynamics Of Melanaphis Sacchari, Monique Ferreira De Souza

LSU Doctoral Dissertations

Sugarcane aphid, Melanaphis sacchari Zehner, is now widely established in sorghum, Sorghum bicolor L., production areas of the United States and is an important economic pest. However, detailed studies of temperature, host range and plant resistance effects on the biology and population parameters of the M. sacchari biotype responsible for the sorghum outbreak in the United States have not been performed previously. Therefore, the present study aimed to investigate: 1) How temperatures affect M. sacchari 2) M. sacchari interaction with host plants 3) M. sacchari interaction with sorghum genotypes. The response of M. sacchari to six different constant temperatures (15, …

Risk Assessment Of Fall Armyworm Resistance To Transgenic Corn Containing Single Or Pyramided Bacillus Thuringiensis Genes, Ying Niu

LSU Doctoral Dissertations

The fall armyworm, Spodoptera frugiperda (J.E. Smith), is a target pest of Bacillus thuringiensis (Bt) crops in North and South America. However, after more than two decades of the intense use of Bt crop technology, S. frugiperda has developed resistance to Bt corn in several countries. The objectives of this study were: 1) to characterize the inheritance and fitness costs of Cry1A.105 resistance in S. frugiperda; 2) to evaluate larval survival and plant injury of Cry1A.105-susceptibile, -resistant, and -heterozygous S. frugiperda populations on transgenic corn plants containing single or pyramided Bt genes; 3) to estimate the frequency of Cry2Ab2 …

Incorporation Of Biorationals And Trap Crop For Stink Bug Management In Soybeans, Kukuh Hernowo

LSU Doctoral Dissertations

Stink bugs are one of the most important seed sucking pests impacting soybean production in Louisiana. Exploration of chemicals that exhibit attraction or repellent activities toward this major pest would be beneficial to develop a push-pull strategy against this pest complex. Spinosad and neem are two commercially available natural insecticides that were claimed to have attractant and repellent activities against stink bugs. To test the potential of these chemicals, a series of experiments was conducted to investigate the olfactory, tactile, feeding, and oviposition preference of stink bugs toward different commercial spinosad products and neem. Additionally, two years of field experiments …

Ecology And Biology Of The Redbanded Stink Bug, Piezodorus Guildinii (Westwood) In Louisiana, Anup Bastola

LSU Doctoral Dissertations

The redbanded stink bug, Piezodorus guildinii (Westwood) is an invasive stink bug species that was first documented as a soybean pest in Louisiana during the year 2000. This species continues to expand northward in the MidSouth but information is lacking on its biology and ecology in the U.S. In order to determine P. guildinii’s northern range, studies were designed to investigate the cold tolerance ability of this species. The mean supercooling points of adult P. guildinii ranged from highest -8.3 ± 0.2°C in March to the lowest of -11.0 ± 0.2°C in January. Evaluation of lethal exposure time …

Evaluation Of Control Tactics For Management Of Sweetpotato Weevil (Coleoptera: Curculionidae), Jie Chen

LSU Doctoral Dissertations

Sweetpotato weevil (SPW), Cylas formicarius elegantulus (Summer), is the most damaging root-feeding insect of sweetpotato, Ipomoea batatas L. (Lam), worldwide. The efficacy and compatibility of host plant resistance and insecticide control were evaluated in this dissertation. cv. Beauregard is the most susceptible cultivar for oviposition and offspring performance of SPW compared to cvs. Evangeline and Murasaki. The oviposition preference was shaped by the larval experience of SPW, providing evidence in support of the Hopkins’ Host-Plant Selection Principle. Although oviposition on cv. Murasaki was reduced, the egg capacity of SPW developed on cv. Murasaki was not decreased, indicating an adaptive behavior …

Determining The Influence Of Imidacloprid And Glufosinate Ammonium On The Population Dynamics Of Twospotted Spider Mite Populations In Louisiana Cotton, Sebe Anthony Brown

LSU Doctoral Dissertations

Twospotted spider mites, Tetranychus urticae, is an important agricultural pest of many field crops worldwide. This study investigated the impacts of imidacloprid seed treatments on populations of twospotted spider mites while also investigating if exogenous applications of jasmonic acid can offset any hormone modulating effects caused by seed treatments. Imidacloprid seed treatments significantly increased cumulative adult mite days in 2013 but not 2015 or 2016 in the field. Applications of 10 millimolar jasmonic acid did not reduce mite severity or injury in all field trials. Imidacloprid seed treatments significantly increased all spider mite life stages in the laboratory while applications …

Termite Gut Microbes As Tools And Targets For Termite Control, Chinmay Vijay Tikhe

LSU Doctoral Dissertations

The Formosan subterranean termite (FST), Coptotermes formosanus, is an invasive urban pest in the United States. Colonies of the FST are dependent on the symbiotic gut protozoa for cellulose digestion in the workers’ guts, and the gut bacterial community is known to provide essential nutrients to the termite. The objectives of this PhD research were to develop and evaluate paratransgenesis and phage therapy for termite control. During this study, a termite gut bacterium: Trabulsiella odontotermitis was genetically engineered and was evaluated as a ‘Trojan horse’ for paratransgenesis. We proved that T. odontotermitis can tolerate 50 times more concentration of ligand-Hecate …