Life Sciences Commons^™

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 …

The Effects Of Juvenile Exposure To Sub-Lethal Concentrations Of Pesticides On The Adult Reproductive Biology Of The Male Southern House Mosquitoe, Culex Quinquefasciatus, Shiloh Dean Judd

LSU Master's Theses

Mosquitoes transmit pathogens capable of causing significant diseases, the worst of which can permanently disfigure or kill. Mosquito control efforts can be strengthened by better understanding all aspects of mosquito biology, but there is deficient information regarding sperm production in male mosquitoes. Understanding the sperm production and capacity of vector species may reveal new control strategies.

The goal of this research was to determine if larval exposure to sub-lethal concentrations, defined as killing less than half of the sample population, of pesticides negatively impacts the adult male reproductive health of the southern house mosquito, Culex quinquefasciatus Say. This study quantified …

Ecology Of Emerald Ash Borer (Agrilus Planipennis: Buprestidae) In Louisiana, Balwinder Kaur

LSU Master's Theses

In 2015, emerald ash borer (EAB) was detected in North Louisiana (LA). There is no information on wood inhabiting insects of green ash (Fraxinus pennsylvanica Marshall) trees, phenology and parasitoid establishment in LA. The first objective of the study was to quantify the insect assemblages and to compare their diversity, abundance and evenness within the epicenter of the EAB infestations in North LA including regions in Central and South LA where EAB has not been detected yet. We established four treatments, based on log diameter: small and large; and log condition: dead and live for green ash. All the …

Residual Effects Of Termiticides On Mortality Of Formosan Subterranean Termites, Coptotermes Formosanus Shiraki, In Substrates Subjected To Flooding, Rajani Sapkota

LSU Master's Theses

Formosan subterranean termites (Coptotermes formosanus Shiraki) are one of the most important economic insects in the Southern US since they cause severe and costly damage to properties. Soil treatment with termiticides is the most widely used and reliable method for termite prevention, but their efficacy after a home floods, an all too common event for a homeowner in recent years, has prompted many pest control companies to suggest a new treatment is necessary. This can be expensive and possibly unnecessary. However, several factors such as termiticide water solubility and binding properties, soil type and soil leachability and the inherent …

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 …

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, …

Susceptibility Of Field-Collected Pupations Of The Corn Earworm, Helicoverpa Zea (Boddie) (Lepidoptera: Noctuidae) From Three Southern States Of The U.S. To Cry1a.105 And Cry2ab2 Proteins, Gagandeep Kaur

LSU Master's Theses

The corn earworm (CEW), Helicoverpa zea (Boddie) (Lepidoptera: Noctuidae), is a major target pest of pyramided Bt corn and Bt cotton in the U.S. In 2016 and 2017, notable corn ear damage and larval survival of CEW were observed on pyramided Cry1A.105/Cry2Ab2 corn in some fields in northeast Louisiana. The objectives of this study were 1) to determine if the ear damage and larval survival observed in the area were due to resistance development to the Bt proteins in the plants, and 2) if resistance had occurred, to determine the approximate distributions of the resistance in the southern region of …

Impact Of Sorghum Cultivar, Phenology, Nitrogen, And Silicon Fertilization On Melanaphis Sacchari Biology, Luna Lama

LSU Master's Theses

The sugarcane aphid, Melanaphis sacchari (Zehntner) (Hemiptera: Aphididae), is an invasive pest of grain sorghum, Sorghum bicolor (L.) Moench. Since its first outbreak in sorghum in 2013, severe infestations have spread throughout the southern U.S. causing high economic losses. While insecticidal control has mitigated some of the impacts of this pest, a sustainable ecology-based management program is needed to reduce reliance on chemical control. We studied the effects of silicon (rates equivalent to 0 and 3360 kg Si/ha) and nitrogen (rates equivalent to 0, 110, and 220 kg N/ha) on M. sacchari growth and reproduction on resistant (DKS 37-07) and …

Characterizing The Physiological Role Of Inward Rectifier Potassium (Kir) Channels In Tick Salivary Gland Function, Zhilin Li

LSU Master's Theses

The tick salivary gland is a critical tissue that enables blood feeding, maintenance of the ionic gradients, and facilitates pathogen transmission. Therefore, the broad objective of this investigation was to leverage pharmacological approaches to investigate the role of potassium ion channels to salivary gland function of Amblyomma americanum in an effort to identify a tractable target site for therapeutic development.

Data collected in Chapter 2 clearly illustrated that the A. americanum salivary gland is reliant upon inward rectifier potassium (Kir) channels for fluid secretion, which was similar to previous work performed by our laboratory on Drosophila salivary gland. Therefore, the …

Determining Bioindicators For Coastal Tidal Marsh Health Using The Food Web Of Larvae Of The Greenhead Horse Fly (Tabanus Nigrovittatus), Devika Rajeev Bhalerao

LSU Master's Theses

The greenhead horse fly Tabanus nigrovittatus Macquart is native to coastal marshlands from Texas to Nova Scotia. The larvae are apex invertebrate predators and their development is dependent on the food web in the soil. Surveillance of T. nigrovittatus after the 2010 Deepwater Horizon oil spill in the Gulf of Mexico showed population crashes of adults in the coastal marshes of East Louisiana near places where oil made landfall, but not in West Louisiana where the oil did not reach. Sediment collection in 2011 from West and East Louisiana revealed larval population crashes in the Eastern coastal region. We hypothesized …