Sheehy, L (2024) Investigation of the genetic architecture of Phasmarhabditis hermaphrodita and other wild isolated Phasmarhabditis species. Doctoral thesis, Liverpool John Moores University.

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Abstract

The gastropod parasitic nematode Phasmarhabditis hermaphrodita was formulated into a biological control agent (Nemaslug®) to kill slugs and snails over 30 years ago and is commonly used as an alternative to chemical molluscicides in agriculture. However, the genome of P. hermaphrodita (or any other Phasmarhabditis species) is unknown; and currently no complete sequence of either the mitochondrial or nuclear genome are available. Similarly, the relationships between Phasmarhabditis and their bacterial microbiota are unknown. It had been thought that P. hermaphrodita vectored the bacterium Moraxella osloensis (the bacteria on which P. hermaphrodita is grown on an industrial scale at BASF) into slugs to kill them. Here, I sequenced the genomes of several Phasmarhabditis spp. and analysed the microbial communities of worms and slug hosts. Metagenomic profiling of the bacterial communities associated with several Phasmarhabditis spp. after they had killed their slug host (Deroceras reticulatum) was undertaken, casting doubt on the association between the worms and M. osloensis and that model of pathogenicity. Metagenomic profiling of resistant and susceptible slug hosts was used to investigate how the host microbiome is affected by an infection with P. hermaphrodita. Nuclear genomes were assembled, creating a platform for future studies on the genetics of these species. Ultimately, this research has unravelled the DNA blueprint of these interesting and useful species and could potentially lead to genetically modified Phasmarhabditis and more efficacious slug control agents.

Item Type:	Thesis (Doctoral)
Uncontrolled Keywords:	Biological control; Phasmarhabditis hermaphrodita; Parasitic; Gastropod; Metagenomic
Subjects:	G Geography. Anthropology. Recreation > GE Environmental Sciences Q Science > QH Natural history > QH301 Biology
Divisions:	Biological & Environmental Sciences (from Sep 19)
SWORD Depositor:	A Symplectic
Date Deposited:	11 Jun 2024 09:55
Last Modified:	11 Jun 2024 09:55
DOI or ID number:	10.24377/LJMU.t.00023364
Supervisors:	Rae, R and Weedall, G
URI:	https://researchonline.ljmu.ac.uk/id/eprint/23364

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