Overview
Caterpillars, the larvae of moths and butterflies (Lepidoptera), are among the most important pests of agriculture, forestry, apiculture, textile production, and stored foodstuffs in the UK and worldwide. In the UK, vegetable brassicas (e.g., broccoli, cauliflower, kale, and Brussels sprouts) are the main crops targeted, although other fruits and vegetables can be affected.
About this opportunity
Internationally, some lepidopteran species such as fall armyworm (native to the Americas) have become invasive pests across tropical Africa and Asia, and these caterpillars can consume 30 species of economically important plants. Current control is overly reliant on pesticides, and many lepidopteran pests have become resistant to multiple pesticide classes. A potential alternative method of environmentally friendly lepidopteran control is through the use of bacterial symbionts that are transmitted from mother to egg. The most widespread of these is Wolbachia, which is present in over 50% of terrestrial arthropods on average but is even more common in Lepidoptera (80% of species, and a quarter-to-one-third of individuals, are infected). Wolbachia can manipulate the reproduction of its host, causing cytoplasmic incompatibility (CI: early death of progeny from matings between infected males with uninfected females, or between parents infected by different Wolbachia strains) or male killing (selective death of male embryos), among other phenotypes. The toxin genes responsible for the reproductive manipulations are usually encoded by prophages in the Wolbachia genome. Releases of Wolbachia-infected male mosquitoes have been shown to successfully suppress wild mosquito populations at several sites around the world, but research on lepidopteran pests has lagged behind.
Aims & Objectives: In this project, you will tackle this major research gap that is hindering potential breakthroughs in pest control by collecting British moths and butterflies and isolating their Wolbachia strains into existing insect cell lines maintained in the Tick Cell Biobank at University of Liverpool. Through integrated application of ‘omics technologies (including next-generation genome sequencing on Illumina and Oxford Nanopore platforms), gene synthesis and cloning, RNA-Seq, and proteomics, you will determine the potential of these isolated symbionts to cause CI or male killing, and will generate recombinant versions of the toxins responsible by cloning into E. coli, yeast or baculovirus systems. Following biochemical characterisation of the toxins and accessory proteins from the prophages, you will compare the effects of injecting these recombinants into model lepidopteran pests (e.g., cabbage white butterflies and flour moths) with trans-infection of live Wolbachia from culture material. Phenotyping of embryos after crossing Lepidoptera in the lab will enable the student to identify the most promising Wolbachia strains, and toxin combinations, for pest control. Thus, molecular characterisation of the toxins alongside phenotypic screening will facilitate mechanistic understanding of their effects on lepidopteran reproduction, which in turn will provide a rational basis for decisions around future field deployment of Wolbachia organisms, or transgenic insects expressing Wolbachia toxins. The project will include placements at the headquarters of New England Biolabs in Massachusetts, USA, where you will gain skills in gene synthesis, cloning, proteomics, and cutting-edge sequencing approaches.
Applicants are expected to hold (or about to obtain) a minimum upper second-class undergraduate honours degree (or equivalent) in biotechnology or microbiology. Research experience in cell culture, cloning and bioinformatics is desirable.
This project is a CASE partnership project with New England Biolabs.