Control of parasitic infections in grazing livestock is under severe strain from drug resistance and climate change, and new approaches are urgently needed. Foraging on ‘bioactive’ plants that inhibit parasites and boosting predatory fungi in dung that feed on developing parasite stages, show promise but more work is needed to determine how to maximise their impact.
The central idea behind this project is that natural biological environments can stimulate responses to augment effects of plant and fungal metabolites against livestock parasites.
There are good reasons to hypothesise that plants subject to natural herbivory and infection, hence ‘nibbled and riddled’, will increase expression of defensive molecules (Plant Specialized Metabolites, PSM) since many such compounds are protective in nature. Condensed tannins, for example, are unpalatable and inhibit digestion but at optimal levels kill parasites in the ruminant gut and increase growth and performance. In the dung, fungi that are normally saprophytic are known to convert to predatory behaviour when nematode density is high, and then secrete compounds that kill and digest developing parasites, reducing onward transmission. It is therefore possible that a biologically rich ‘rotten’ dung-soil environment could stimulate behaviour change in fungi and increase expression of useful nematodical compounds.
This project will explore the consequences of biotic interactions for the expression and effects of antiparasitic molecules by plants and fungi. It brings cutting-edge chemistry into the study of natural ecological interactions with a view to enhancing the utility of nature-based solutions for animal health.
Chemical profiles of plant extracts will be compared when grown under protection from herbivores/pests versus exposed to varying degrees of natural challenge. Tree, shrub and legume/forb species that are palatable to ruminants and with evidence of antiparasitic bioactivity will be chosen, e.g. willow, hazel, chicory. Mesh bags will be used to protect plants or plant parts from insects and other pests, alongside variable browsing and mechanical pruning. Chemical profiles will be analysed using high performance liquid chromatography and associated informatics for chemical characterization, including tannin structure where tannins are present. Extracts from fungi will be similarly compared when grown in medium inoculated with nematodes and ruminant dung that is sterile versus naturally colonized or augmented with dung-breeding organisms. The antiparasitic effects of chemicals extracted from these different sources will be assessed using in vitro bioassays, mainly nematode larval exsheathment and mortality rates. Results will be used to assess the relevance of the biotic environment for the bioactivity of plants and fungi against parasites of farmed ruminants. Epidemiological modelling will be applied to estimate consequences for parasite transmission under climate change.
If effects are stronger in natural communities than when extracts are harvested from more sterile pipelines, this would suggest benefits from integrating these solutions into diverse farm environments. Ways to exploit any synergies found will therefore be co-produced with livestock farmers through field schools and other knowledge exchange activities.
The student will benefit from training in chemistry, parasitology, ecology and animal health, preparing them for diverse career possibilities in scientific research and also government and private sectors.
Essential candidate background:
- First degree in biology, chemistry, animal or plant science or other relevant discipline.
- Demonstrated interest in animal health or in exploring biological or chemical interactions in a laboratory environment.
Photo by Jesse Bauer on Unsplash
|Profile: Eric Morgan|
Institution: Queen's University, Belfast
Department/School: School of Biological Sciences
Dr Stephen Cochrane – Queens University Belfast, School of Chemistry and Chemical Engineering
Academic profile: https://pure.qub.ac.uk/en/persons/stephen-cochrane
Email address: firstname.lastname@example.org
Prof Ilias Kyriazakis – Queens University Belfast, School of Biological Sciences
Academic profile: https://pure.qub.ac.uk/en/persons/ilias-kyriazakis
Email address: I.Kyriazakis@qub.ac.uk
- Cable et al. 2017. Global change, parasite transmission and disease control: lessons from ecology. Philosophical Transactions of the Royal Society B 372, 1719.
- Cochrane et al. 2015. Production of new cladosporin analogues by reconstitution of the polyketide synthases responsible for the biosynthesis of this antimalarial agent. Angewandte Chemie International Edition 55, 664-668.
- Cochrane et al. 2020. From plant to probe: semi-synthesis of labelled undecaprenol analogues allows rapid access to probes for antibiotic targets. Chemical Communications 56, 8603.
- Yang et al. 2020. Natural diversity in the predatory behavior facilitates the establishment of a robust model strain for nematode-trapping fungi. Proceedings of the National Academy of Sciences USA 117, 6762-6770.
- Hoste et al. 2015. Tannin containing legumes as a model for nutraceuticals against digestive parasites in livestock. Veterinary Parasitology 212, 5-17.
- Nombela et al. 2009. Pre-infestations of tomato plants by whiteflies (Bemisia tabaci) or aphids (Macrosiphum euphorbiae) induce variable resistance or susceptibility responses. Bulletin of Entomological Research 99. 183-191.