Theses and Dissertations

Issuing Body

Mississippi State University

Advisor

Krishnan, Natraj

Committee Member

Harris, Jeffrey W.

Committee Member

Ahn, Seung-Joon

Date of Degree

5-13-2022

Document Type

Graduate Thesis - Campus Access Only

Major

Agricultural Life Sciences

Degree Name

Master of Science (M.S.)

College

College of Agriculture and Life Sciences

Department

Department of Biochemistry, Molecular Biology, Entomology and Plant Pathology

Abstract

The tarnished plant bug, Lygus lineolaris, is an economically important polyphagous pest with a broad host range. With occurrence of insecticide resistance, strategies to limit its ability to reproduce, which would curb population growth, are becoming increasingly more valuable. Strategies toward this goal include the application of insect growth regulators (IGRs) and utilization of resistant cotton lines. This thesis summarizes experiments that elucidate the physiological underpinnings of the mode of action of novaluron, an IGR, and a cotton chromosome substitution (CS) line on the reproductive physiology of L. lineolaris. Investigations reported herein indicate that novaluron inhibits oviposition by inhibiting ovarian development and decreasing the expression of a gene (LlCHS-1) encoding chitin synthase. Transcriptomic analysis of ovarian tissue of L. lineolaris fed on a resistant CS line compared to a control line revealed the downregulation of genes involved in chitin synthesis and upregulation of genes involved in chitin degradation.

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