Year: 2019
Type: dissertation
Abstract: The cassava whitefly, Bemisia tabaci (Hemiptera: Aleyrodidae), is a highly invasive and destructive \nagricultural pest, with a global distribution. B. tabaci insect has evolved resistance to multiple \ninsecticides, and therefore, new control methods will have to be developed to control this insect. \nThe self-limiting system, which produces a female-specific lethal heritable element and causes \npopulation suppression, works well for control of mosquitoes. The goal of this thesis is to assess \nthe feasibility of creating a self-limiting system in B. tabaci. \nThe self-limiting system requires generating transgenic insects, and this is done via injection of \nconstructs into eggs at the pre-germ-line cell stage (around blastoderm formation), this enables \nstable germline transformation. However, there has been limited research into B. tabaci early \nembryogenesis stages, and therefore it is unclear when transformation constructs will have to be \nintroduced. In this thesis, I conducted confocal microscopy studies to determine the timing of \nearly embryogenesis stages in B. tabaci MED. Unexpectedly, I revealed that early embryogenesis \nin B. tabaci starts before the eggs are oviposited, unlike in mosquitoes and fruitflies. Therefore, \ninjecting laid B. tabaci eggs is too late for obtaining stable transgenic whitefly lines, though \nsomatic transgenics may be obtained. \nPast self-limiting transgenic insects used genes found in the sex determination pathway, for \nfemale-specific lethality, as these were expressed early and had sex-specific splicing. Genes of the \nsex determination pathways in B. tabaci and other hemipteran are largely unknown. Hence, I \nconducted a genome-wide search of 11 publicly available hemipteran genomes to identify their \nsex determination genes. Also, I conducted single-embryonic RNA-seq experiments in B. tabaci to \nassess if these genes undergo sex-specific splicing at the early embryogenesis stages in males and \nfemales. These results identified sex determination genes in B. tabaci and other hemipterans and \nrevealed potential targets for future genetic control methods.
Author: Rebecca Corkill
Language: English
Subfield: Molecular Biology
Domain: Life Sciences
Open Access status: green
Funder: Strong
OpenAlex ID: W3022896491