Date Available

8-9-2021

Year of Publication

2021

Degree Name

Master of Science (MS)

Document Type

Master's Thesis

College

Agriculture, Food and Environment

Department/School/Program

Entomology

First Advisor

Dr. Lynne Rieske-Kinney

Abstract

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 larval weight gain, adult emergence or fecundity, and gene silencing. The model insects, a predator, herbivore, and pollinator, were evaluated in laboratory bioassays following dsRNA exposure and results from these studies demonstrate no nontarget effects on representative model insects.

Additionally, I evaluated these three SPB-specific dsRNAs on pine-associated insects that co-occur with SPB, including a pine engraver, pine defoliator, and decomposer. Lethal effects, sublethal effects such as larval weight gain or food consumption, and relative gene expression were analyzed for these insects, and results show no nontarget effects on these insects that could encounter the treatments were they to be deployed in a pine ecosystem.

Digital Object Identifier (DOI)

https://doi.org/10.13023/etd.2021.313

Funding Information

United States Department of Agriculture, Animal & Plant Health Inspection Service (USDA APHIS): Plant Protection Act 7721, Grant No. AP20PPQS&T00C032; 2019-2021

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