Wahlers, J (2020) The use of spider venom neurotoxin-based fusion proteins as species-selective pesticides. Doctoral thesis, Liverpool John Moores University.

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Abstract

The current generation of synthetic pesticides and anti-parasitic compounds have been linked to numerous ecological issues, such as pollinator decline. However, without their use agricultural output will suffer tremendously and thus alternative solutions must be investigated. An ideal alternative to these pesticides needs to retain the oral/topical toxicity and stability of current treatments, without being toxic to vertebrates and non-target invertebrates such as pollinators. Knottin toxins found in the venom cabals of spiders have been shown to fulfil these criteria, and as such are under investigation as lead compounds for new bio-pesticides.

The downside of these toxin peptides is their lack of oral toxicity. By combining the genes for these peptides with the gene for an orally toxic protein known as Galanthus nivalis agglutinin an orally toxic fusion protein can be expressed. Such fusion proteins have been previously shown to be selective and effective pesticides, with exposure through oral and injection routes being deleterious to lethal for several pest species yet without harming beneficial hymenopterans.

This thesis explores the efficacy of three such neurotoxic fusion proteins in the potential control of helminthic parasites using the model nematode species Caenorhabditis elegans. Survival bioassays and time budget studies were undertaken to determine any potential negative effects of oral, contact and injection exposure to field-realistic levels of Hv1a/GNA on the survival and behaviour of the British bumble bee species Bombus terrestris. Preliminary electrophysiology experiments were also conducted, using affordable extra-cellular recording equipment to determine Hv1a/GNA’s effects on the nervous activity of B. terrestris and the cricket species Gryllus assimilis. Finally, the potential interactions between Hv1a/GNA and the CaV1s of B. terrestris and C. elegans were investigated using homology modelling techniques.

Item Type:	Thesis (Doctoral)
Uncontrolled Keywords:	Venom; Neurotoxin; Pesticide
Subjects:	Q Science > QD Chemistry Q Science > QH Natural history > QH301 Biology R Medicine > RM Therapeutics. Pharmacology S Agriculture > S Agriculture (General)
Divisions:	Biological & Environmental Sciences (from Sep 19)
Date Deposited:	18 Nov 2020 09:21
Last Modified:	04 Jan 2023 10:13
DOI or ID number:	10.24377/LJMU.t.00014018
Supervisors:	Williamson, S, O'Reilly, A and Fitches, E
URI:	https://researchonline.ljmu.ac.uk/id/eprint/14018

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