Exploring the potential of genetic improvement of insects: a case study using the haplodiploid parasitoid wasp Nasonia vitripennis

Shuwen Xia

Research output: Thesisinternal PhD, WU

Abstract

Insects have gained increasing interests in diverse agricultural applications, ranging from the use of insect-derived protein in animal feed to the use of insects as natural enemies of agricultural pests. Using the knowledge of genetics is a powerful way to improve the application of insects in agriculture. The exploitation of genetic variation in insects has been discussed for long time, however, the nature of genetic variation is still largely unexplored for insects outside of well-studies species. The main aim of this thesis was to explore the potential of genetic improvement of insects. To this end, I investigated the genetic basis of wing morphology and associated phenotypic traits in the parasitoid wasp Nasonia vitripennis as a case study. First, I used a modified Animal Model with a pedigree relationship matrix, and the Genomic Restricted Maximum Likelihood method to quantify the amount of genetic variation and variation due to host effects for these traits. Host effects occur because Nasonia species are gregarious wasps, which lay more than one egg into a single host, so that the offspring share a common developmental environment. The results have shown substantial host effects on wing morphology traits, especially for size traits: hosts explained up to 64% of the total phenotypic variation. Significant additive genetic variation were also observed for all traits. Second, I conducted genome-wide association study (GWAS) to further reveal the genetic basis of these traits. Several genomic regions that significantly associated with wing morphology variation were identified. Third, I implemented genomic prediction for wing morphology traits in N. vitripennis to explore its potential in insects. The results have showed promising accuracies based on a cross-validation strategy, which suggests that genomic prediction is feasible in insects. Furthermore, I investigated the relationship between the level of inbreeding and inbreeding depression for wing morphology traits using sex-biased gene expression. I found no evidence for a relationship between inbreeding and sex-biased gene expression, and I did not observe any inbreeding depression for wing morphology traits. Finally, I discussed the potential of improvement of insect parasitoids by selecting better hosts and the implications of the exploration of genetic variation for potential applications in insects selective breeding. Together, this thesis provides important insights into the genetic architecture of wing morphology in the parasitoid wasp Nasonia vitripennis. The findings contribute to the knowledge of the genetic basis of wing morphology traits in insects, and also show the promising potential of using genetic tools to improve insects.

Original languageEnglish
QualificationDoctor of Philosophy
Awarding Institution
  • Wageningen University
Supervisors/Advisors
  • Groenen, M.A.M., Promotor
  • Zwaan, Bas, Promotor
  • Bijma, Piter, Co-promotor
  • Pannebakker, Bart, Co-promotor
Award date24 Apr 2020
Place of PublicationWageningen
Publisher
Print ISBNs9789463953559
DOIs
Publication statusPublished - 24 Apr 2020

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