Life Sciences Commons^™

Emergent Fungal Entomopathogen Does Not Alter Density Dependence In A Viral Competitor, Andrew M. Liebhold, Ruth Plymale, Joseph S. Elkinton, Ann E. Hajek

Articles

Population cycles in forest Lepidoptera often result from recurring density-dependent epizootics of entomopathogens. While these systems are typically dominated by a single pathogen species, insects are often infected by multiple pathogens, yet little is known how pathogens interact to affect host dynamics. The apparent invasion of northeastern North America by the fungal entomopathogen Entomophaga maimaiga some time prior to 1989 provides a unique opportunity to evaluate such interactions. Prior to the arrival of E. maimaga, the oscillatory dynamics of host gypsy moth, Lymantria dispar, populations were apparently driven by epizootics of a nucleopolyhedrovirus. Subsequent to its emergence, E. …

Plant-Mediated Alteration Of The Peritrophic Matrix And Baculovirus Infection In Lepidopteran Larvae, Ruth C. Plymale, Michael J. Grove, Diana Cox-Foster, Nancy Ostiguy, Kelli Hoover

Articles

The peritrophic matrix (PM) lines the midgut of most insects, providing protection to the midgut epithelial cells while permitting passage of nutrients and water. Herein, we provide evidence that plant-mediated alteration of the PM contributes to the well-documented inhibition of fatal infection by Autographa californica multiple nucleopolyhedrovirus (AcMNPV) of Heliothis virescens F. larvae fed cotton foliage. We examined the impact of the PM on pathogenesis using a viral construct expressing a reporter gene (AcMNPV-hsp70/ lacZ) orally inoculated into larvae with either intact PMs or PMs disrupted by Trichoplusia ni granulovirus occlusion bodies containing enhancin, known to degrade insect intestinal mucin. …

Induction Of Systemic Acquired Resistance In Cotton Foliage Does Not Adversely Affect The Performance Of An Entomopathogen, Ruth C. Plymale, Gary W. Felton, Kelli Hoover

Articles

Baculoviral efficacy against lepidopteran larvae is substantially impacted by the host plant. Here, we characterized how baculoviral pathogenicity to cotton-fed Heliothis virescens larvae is affected by induction of systemic acquired resistance (SAR). Numerous studies have shown that SAR induced by the plant elicitor benzo-(1,2,3)-thiadiazole-7- carbothioic acid S-methyl ester (BTH) can protect against plant pathogens, but reports on the impacts of SAR on chewing herbivores or on natural enemies of herbivores are few. We found that BTH application significantly increased foliar peroxidase activity, condensed tannin levels, and total phenolic levels but did not alter dihydroxyphenolic levels. Consumption of BTH-treated foliage did …

Plant Galls, Michael Paul Grisham

Honors Theses

Plant galls, or cedidia, are defined as

...pathologically developed cells, tissues, or organs of plants that have risen mostly by hypertrophy and hyperplasy under the influence of parasitic organisms like bacteria, fungi, nematoda, mites, or insects.

The plant gall is unique in providing not only food, but shelter as well for its host. While the host benefits, damage to the plant results. Among other things sap flow is disturbed, premature decay results, non-essential parts are developed at the cost of essential parts, and many other injuries occur. A few examples of the benefits of plan galls may be cited. Nitrogen …