PhD Studentship: Characterising the Immune Repertoire of a Global Crop Pest Myzus Periscae

Location: Centre for Ecology and Conservation, Penryn Campus, Cornwall

The University of Exeter’s Centre for Ecology and Conservation is inviting applications for a PhD studentship funded by the Faculty of Environment, Science and Economy to commence on 23 September 2024 or as soon as possible thereafter. For eligible students the studentship will cover Home or International tuition fees plus an annual tax-free stipend of at least £19,237 for 3.5 years full-time, or pro rata for part-time study. International applicants need to be aware that you will have to cover the cost of your student visa, healthcare surcharge and other costs of moving to the UK to do a PhD. The following project is one of four being advertised as part of a competitive process for funding, there is one award available.

Project keywords: Innate immunity, Toll-like receptors, cGAS-STING, host-pathogen interaction, Lysozyme and antimicrobial peptide

Project Background 

It is projected the world must increase crop yield by 40% from current levels to feed the human population of 2050. Insect pests such as aphids are responsible for billions of dollars (USD) of damage. Aphids vector viral and microbial diseases, and directly damage crops. This problem demands effective biocontrol strategies, yet chemical insecticide use is increasingly discouraged. Segregating insecticide resistance also requires contingency strategies to handle pest species: in 2020, insecticide resistance in Green peach aphids (Myzus persicae) caused ~£67 million of economic losses to UK sugar beet agriculture alone. Similar economic threats unquestionably apply to crops attacked by other pest species. A promising strategy already being employed is the use of insect-infecting microbes that can be spread on crops. 

Insect-pathogenic microbes have specific host ranges determined by the host immune system. Insect immunity has been extensively characterised in fruit flies, but also other species of holometabolous insects including flies, beetles, and moths. However, there is a considerable knowledge gap in relation to the aphid immune system, and hemipteran immune systems more generally. From what is known, aphids have many bacterial symbionts, some of which supplement their diet with essential nutrients. However, some facultative symbionts are known to protect aphids against infection by parasites. Perhaps as a consequence, the Green pea aphid Acyrthosiphon pisum, has lost the “Immune deficiency” (Imd) pathway conserved across insects (Gerardo et al., 2010; Genome Biology). Moreover, Green pea aphids succumb to infection easily, and lack critical bacteria-killing enzymatic activity in their blood. It’s thought aphids evolved loss of this immune pathway to avoid harming beneficial bacterial symbionts – however, this has never been formally scrutinized.

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