Investigating novel methods of insect control.

Leigh, Stewart (2019) Investigating novel methods of insect control. Doctoral thesis, University of East Anglia.

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Over half of the world's population is at risk for contracting potentially fatal arboviruses such as dengue or Zika. Treatment of many of the diseases caused by these viruses is limited by the absence and lack of availability of vaccines or cures, prompting strategies to control the viral vectors and prevent disease transmission to humans. In this thesis I investigated two potential vector control strategies- "satyrization" and (/genetic underdominance" to provide proof of principle. Satyrization is a form of reproductive interference whereby unidirectional hybrid mating frequency and asymmetric post-mating effects from seminal fluid protein (Sfp) transfer between species can contribute to the competitive exclusion of one species by another. Satyrization has been documented in nature whereby the dengue vector Aedes aegypti has been shown to suffer population reduction when in sympatry with the less virulent vector Ae. a/bopictus. In this thesis I investigated the underlying mechanics and drivers of satyrization in a series of experiments conducted within closely related members of the Drosophila melanogaster species subgroup. This confirmed the widespread presence of satyrization and demonstrated a potential link between hybrid mating and asymmetric effects of Sfps. I also found that resistance to satyrization did not quickly evolve between D. melanogaster and D. simulans as active satyrization was still present between the species after 12 generations in sympatry, in contrast to what has been reported between Aedes mosquitoes. My underdominance research focussed on a (/killer-rescue'' strategy. This comprises a lethal Minute phenotype caused by knockouts (KO} of key haploinsufficient Ribosomal protein (Rp) genes, and a transgenic Rescue gene on a separate chromosome that contains functional copies of the KO Rp genes to nullify the costly effects of the Minute phenotype. This allows the lethal KO Rp alleles to spread through a population for multiple generations. I developed and built this Rescue gene in D. melanogaster and quantified the fitness costs associated with Minute, to then theoretically model and simulate the spread of an underdominant release. My model showed that a single 1:1 release of this underdominant killer-rescue system could provide insect control for up to 20 generations. However, the Rescue construct in the form that I developed requires further development before it is fit for purpose as it would not express effectively in female carriers, and very few males carried the transgene. This informed the next steps required for redesigning the Rescue constructs. Overall my thesis research produced a promising evaluation of the potential use of satyrization and genetic underdominance systems for insect control, and opened up important new avenues for further study.

Item Type: Thesis (Doctoral)
Faculty \ School: Faculty of Science > School of Biological Sciences
Depositing User: Chris White
Date Deposited: 12 Apr 2021 10:11
Last Modified: 30 Sep 2022 01:38


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