Functionally distinct T-helper cell phenotypes predict resistance to different types of parasites in a wild mammal

The adaptive immune system is critical to an effective response to infection in vertebrates, with T-helper (Th) cells pivotal in orchestrating these responses. In natural populations where co-infections are the norm, different Th responses are likely to play an important role in maintaining host health and fitness, a relationship which remains poorly understood in wild animals. In this study, we characterised variation in functionally distinct Th responses in a wild population of Soay sheep by enumerating cells expressing Th-subset specific transcription factors and quantifying Th-associated cytokines. We tested the prediction that raised Th1 and Th2 responses should predict reduced apicomplexan and helminth parasite burdens, respectively. All measures of Th-associated cytokine production increased with age, while Th17- and regulatory Th-associated cytokine production increased more rapidly with age in males than females. Independent of age, sex, and each other, IL-4 and Gata3 negatively predicted gastro-intestinal nematode faecal egg count, while IFN-γ negatively predicted coccidian faecal oocyst count. Our results provide important support from outside the laboratory that Th1 and Th2 responses predict resistance to different kinds of parasites, and illustrate how harnessing specific reagents and tools from laboratory immunology will illuminate our understanding of host-parasite interactions in the wild

Host resources and parasite traits interact to determine the optimal combination of host parasite-mitigation strategies.

Organisms have evolved diverse strategies to manage parasite infections. Broadly, hosts may avoid infection by altering behaviour, resist infection by targeting parasites or tolerate infection by repairing associated damage. The effectiveness of a strategy depends on interactions between, for example, resource availability, parasite traits (virulence, life-history) and the host itself (nutritional status, immunopathology). To understand how these factors shape host parasite-mitigation strategies, we developed a mathematical model of within-host, parasite-immune dynamics in the context of helminth infections. The model incorporated host nutrition and resource allocation to different mechanisms of immune response: larval parasite prevention; adult parasite clearance; damage repair (tolerance). We also considered a non-immune strategy: avoidance via anorexia, reducing intake of infective stages. Resources not allocated to immune processes promoted host condition, whereas harm due to parasites and immunopathology diminished it. Maximising condition (a proxy for fitness), we determined optimal host investment for each parasite-mitigation strategy, singly and combined, across different environmental resource levels and parasite trait values. Which strategy was optimal varied with scenario. Tolerance generally performed well, especially with high resources. Success of the different resistance strategies (larval prevention or adult clearance) tracked relative virulence of larval and adult parasites: slowly maturing, highly damaging larvae favoured prevention; rapidly maturing, less harmful larvae favoured clearance. Anorexia was viable only in the short term, due to reduced host nutrition. Combined strategies always outperformed any lone strategy: these were dominated by tolerance, with some investment in resistance. Choice of parasite mitigation strategy has profound consequences for hosts, impacting their condition, survival and reproductive success. We show that the efficacy of different strategies is highly dependent on timescale, parasite traits and resource availability. Models that integrate such factors can inform the collection and interpretation of empirical data, to understand how those drivers interact to shape host immune responses in natural systems

Crop Updates 2004 - Cereals

This session covers twenty eight papers from different authors: PLENARY 1. Declining profitability in continuous cropping systems. Is more wheat the answer on Duplex soil? Dr Wal Anderson, Department of Agriculture 2. Disease implications of extending the wheat phase in low-medium rainfall areas, Dr Vivian Vanstone and Dr Robert Loughman, Department of Agriculture 3. Prolonged wheat phase on duplex soils – where do weeds set the boundary? Vanessa Stewart, Department of Agriculture WHEAT AGRONOMY 4. Management of small grain screenings in wheat, Dr Wal Anderson and Dr Darshan Sharma, Department of Agriculture 5. Agronomic responses of new wheat varieties, Christine Zaicou-Kunesch, Dr Darshan Sharma, Brenda Shackley, Dr Mohammad Amjad, Dr Wal Anderson and Steve Penny,Department of Agriculture 6. Managing wheat yield reduction from wide rows, Dr Mohammad Amjad and Dr Wal Anderson, Department of Agriculture 7. Row spacing and stubble effect on wheat yield and ryegrass seed set, Glen Riethmuller, Department of Agriculture 8. Grain protein management – lessons learnt on the south coast, Jeremy Lemon, Department of Agriculture 9. Unravelling the mysteries of optimum seed rates, Dr Wal Anderson, Dr Darshan Sharma, Brenda Shackley and Mario D’Antuono, Department of Agriculture 10. Agronomic features for growing better wheat – south east agricultural region 2003, Dr Mohammad Amjad, Veronika Reck and Ben Curtis, Department of Agriculture 11. Agronomic responses of new wheat varieties – great southern agricultural region 2003, Brenda Shackley and Judith Devenish, Department of Agriculture 12. Variety specific responses of new wheat varieties – central agricultural region 2003, Dr Darshan Sharma and Dr Wal Anderson, Department of Agriculture 13. Agronomic responses of new wheat varieties – northern agricultural region 2003, Christine Zaicou-Kunesch, Melaine Kupsch and Anne Smith, Department of Agriculture BARLEY AND OAT AGRONOMY 14. Gairdner for high rainfall – where does Baudin fit in? Blakely Paynter, Roslyn Jettnerand Leanne Schulz, Department of Agriculture 15. Oaten hay – varieties and agronomy, Blakely Paynter, Jocelyn Ball and Tom Sweeny, Department of Agriculture NUTRITION 16. In-furrow fungicide applications in liquid fertiliser, Dr Stephen Loss, CSBP Ltd 17. Elemental sulphur as a fertiliser source in Western Australia, Ashleigh Brooks1A, Justin Fuery2, Geoff Anderson3 and Prof Zed Rengel1,1UWA, 2Summit FertilizerFertilisers and 3Department of Agriculture 18. Genetic variation in potassium efficiency of barley, Paul Damon and Prof. Zed Rengel, Faculty of Natural and Agricultural Sciences, UWA 19. Managing protein through strategic N applications, Eddy Pol and Dr Stephen Loss, CSBP Ltd 20. Nitrogen management for wheat in high rainfall cropping areas, Narelle Hill1, Ray Tugwell1, Dr Wal Anderson1, Ron McTaggart1and Nathan Moyes2, 1Department of Agriculture and 2Landmark 21. Flag smut resistance in current WA wheat varieties, John Majewski and Dr Manisha Shankar, Department of Agriculture 22. Rust resistance update for wheat varieties in WA, Dr Manisha Shankar, John Majewski and Jamie Piotrowski, Department of Agriculture PESTS AND DISEASES 23. Stripe rust in WA – where was it and what can we learn from 2003? Dr Robert Loughman and Ciara Beard, Department of Agriculture 24. Foliar disease management – a key factor in the adoption of Baudin and Hamlin barley, Dr Kithsiri Jayasena, Dr Rob Loughman, Kazue Tanaka and Grey Poulish, Department of Agriculture 25. Validating aphid and virus risk forecasts for cereals, Dr Debbie Thackray, Rohan Prince and Dr Roger Jones, Department of Agriculture and Centre for Legumes in Mediterranean Agriculture HARVESTING 26. Swathing Gairdner barley at 30% moisture, Peter Nelson¹ and Nigel Metz², ¹Cooperative Bulk Handling and ² Fitzgerald Biosphere Group MODELLING 27. Development of a web based grower decision aid application for cereal growers, Dr Leisa Armstrong1, Yee Leong (Alex) Yung1and Dr Moin Salam2 1School of Computer and Information Science, Edith Cowan University; and 2Department of Agriculture 28. Wheat varieties updated in ‘Flowering Calculator’ – a model predicting flowering time, Brenda Shackley, Dr David Tennant, Dr Darshan Sharma and Christine Zaicou‑Kunesch, Department of Agricultur

Long-term temporal trends in gastrointestinal parasite infection in wild Soay sheep

Monitoring the prevalence and abundance of parasites over time is important for addressing their potential impact on host life histories, immunological profiles and their influence as a selective force. Only long-term ecological studies have the potential to shed light on both the temporal trends in infection prevalence and abundance and the drivers of such trends, because of their ability to dissect drivers that may be confounded over shorter time scales. Despite this, only a relatively small number of such studies exist. Here, we analysed changes in the prevalence and abundance of gastrointestinal parasites in the wild Soay sheep population of St. Kilda across 31 years. The host population density (PD) has increased across the study, and PD is known to increase parasite transmission, but we found that PD and year explained temporal variation in parasite prevalence and abundance independently. Prevalence of both strongyle nematodes and coccidian microparasites increased during the study, and this effect varied between lambs, yearlings and adults. Meanwhile, abundance of strongyles was more strongly linked to host PD than to temporal (yearly) dynamics, while abundance of coccidia showed a strong temporal trend without any influence of PD. Strikingly, coccidian abundance increased 3-fold across the course of the study in lambs, while increases in yearlings and adults were negligible. Our decades-long, intensive, individual-based study will enable the role of environmental change and selection pressures in driving these dynamics to be determined, potentially providing unparalleled insight into the drivers of temporal variation in parasite dynamics in the wild

Long-term temporal trends in gastrointestinal parasite infection in wild Soay sheep

Data associated with "Long-term temporal trends in gastrointestinal parasite infection in wild Soay sheep", published in the journal Parasitology. Data consist of samples collected from individuals in the Augusts of 1988-2018 and the prevalence and abundance of different parasites: fec (strongyles), foc (coccidia), nematodirus, trichuris, capillaria, and moniezia. The suffic "-prev" indicates that this is a variable indicating the presence or absence of a given parasite. The "anthelmintic" variable is a binary variable stating whether or not an animal had been treated with an anthelmintic in the 12 months prior to sample collection. SOAY SHEEP PROJECT DATA REUSE: The attached file(s) contain data derived from the long term field project monitoring individual Soay sheep on St Kilda and their environment. This is a request to please let us know if you use them. Several people have spent the best part of their careers collecting the data. If you plan to analyse the data, there are a number of reasons why it would be very helpful if you could contact Dan Nussey ([email protected]) before doing so. [NB. If you are interested in analysing the detailed project data in any depth you may find it helpful to have our full relational database rather than the file(s) available here. If so, then we have a simple process for bringing you onto the project as a collaborator.] 1) The data can be subject to change due to updates in the pedigree, merging of records, occasional errors and so on. 2) The data are complex and workers who do not know the study system may benefit from advice when interpreting it. 3) At any one time a number of people within the existing project collaboration are analysing data from this project. Someone else may already be conducting the analysis you have in mind and it is desirable to prevent duplication of effort. 4) In order to maintain funding for the project(s), every few years we have to write proposals for original analyses to funding agencies. It is therefore very helpful for those running the project to know what data analyses are in progress. 5) Individual identifiers may vary relative to other data archives from papers using the individual-level data