The genetic control of agricultural pests (Plutella xylostella, L. and Tribolium castaneum, Herbst)

Thesis

The interaction between an increasing global human population and a number of important long-term trends and issues are putting strain on food production. Insects represent a significant food security concern causing up to 15% of global crop losses. Conventional chemical methods are ineffective; inducing resistance and degrading the environment. Sustainable alternatives are sought.

The sterile insect technique provides a sustainable solution. Genetic engineering can augment this historic technique by replacing radiation-induced sterilization with sperm-specific nuclease expression to introduce double-stranded DNA breaks in the gametes of mass-reared and released males. This paternal-effect system is dependent on elucidation of appropriate sperm-specific promoters and suitable chaperone-nuclease combinations. This thesis develops this technology in the SIT neglected insect orders, the Lepidoptera and Coleoptera. Specifically the Plutella xylostella (Plutella xylostella, L.) and the red flour beetle (Tribolium castaneum, Herbst).

I provide the foundations for a paternal-effect genetic-control-system in both species by developing a conditional sperm-specific expression system in Plutella xylostella and a female-specific expression system in Tribolium.

Mass-rearing insects for the genetic control of a species can be augmented by recent developments in RNAi. I show that the sex ratio of Tribolium can be adjusted by treatment with dsRNA transformer, producing pseudomales as an additional bonus.

In addition, an exploratory data analysis of producing transgenic lines in insects using piggyBac was undertaken. As well as providing a comprehensive compendium and assessment of the transgenic literature, something not yet published elsewhere, a predictive model was produced that could be very useful to a wide diversity of researchers in insect molecular biology, developmental biology, disease biology and genetics.

It is hoped that this work will contribute towards the effective control of the Plutella xylostella in the near term, and form a model for the sustainable control of other lepidopteran and coleopteran species through genetic pest management.

Authors: Gregory, M

• DOI: 10.5287/ora-yebb5rp9o
• Type of award: DPhil
• Level of award: Doctoral
• Awarding institution: University of Oxford
• Language: English
• Keywords: Diamondback moth; Paternal effect; dsRNA; Markov Chain Monte Carlo Method; Spermatogenesis; Spermiogenesis; Plutella xylostella; RNAi; Red flour beetle; Female lethal; Food production; Sperm lethal; piggyBac; Sterile insect technique; transformation; Tribolium castaneum
• Subjects: Genetic engineering; Molecular biology; Insect sterilization; Insect pests--Control; Food security; Double-stranded RNA