Date Available

4-28-2018

Year of Publication

2016

Document Type

Doctoral Dissertation

Degree Name

Doctor of Philosophy (PhD)

College

Agriculture, Food and Environment

Department/School/Program

Entomology

Advisor

Dr. Subba Reddy Palli

Abstract

The bed bug, Cimex lectularius is an obligate hematophagous ectoparasite that feeds on humans. The increase in travel and development of insecticide resistance to commercially available insecticides have enabled the bed bug population to resurge, causing economical and psychological trauma to the human population. Lack of knowledge about the basic molecular biology of bed bugs has motivated us to study the key aspects of molting, metamorphosis, and reproduction. A blood meal triggers expression of various genes that enable bed bugs to molt or undergo metamorphosis. Molting and metamorphosis in bed bugs are regulated by two key hormones: 20-hydroxyecdysone (20E) and juvenile hormone (JH). JH induces expression of Krüppel homologue 1 (Kr-h1) gene. Higher expression of Kr-h1 in the penultimate nymphal instar represses ecdysone inducible gene E93 and the development of adult characteristics in the insect. E93 is expressed during the last instar stage in the absence of Kr-h1. E93 promotes the development of adult structures and metamorphosis to the adult stage. Studies on reproduction have also shown that blood meal and mating are essential for vitellogenin gene expression and oocyte maturation in bed bugs. JH and 20E regulate reproduction in bed bugs. Detailed studies on the involvement of juvenile hormone in reproduction using the next generation sequencing technology identified genes that regulate reproduction in bed bugs. V-Maf, avian musculoaponeurotic fibrosarcoma oncogene homolog B (MafB), forkhead box protein (Foxl2) and heparanase were found to play key roles in regulation of reproduction. The role of ABC transporters was also studied using RNA interference. ABC transporters (ATP-binding cassette) are involved in active transport of various molecules including steroid hormones, cuticle lipids, and other molecules. ABC transporters were also shown to be involved regulation of reproduction, molting and metamorphosis in bed bugs. This study lays a foundation for future research aimed at the development of novel methods for controlling bed bugs.

Digital Object Identifier (DOI)

http://dx.doi.org/10.13023/ETD.2016.079

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