Dr James Ryalls


"My research interests focus on understanding the mechanisms driving herbivore responses to future changes in climate and atmospheric conditions"

James Ryalls

Postdoctoral Researcher

Centre for agri-environmental research

School of Agriculture, Policy and Development

University of Reading




DOMINO stands for Degradation  of Odour signals by air pollution: chemical Mechanisms, plume dynamics and INsect-Orientation behaviour

In collaboration with Dr Robbie Girling (University of Reading; UoR), Dr Christian Pfrang (UoR), Dr Ben Langford (Centre of Ecology & Hydrology; CEH), Dr Eiko Nemitz (CEH) and Dr Michael Birkett (Rothamsted Research), this project focuses on understanding the mechanisms by which air pollution can alter insect orientation behaviour and the ecological consequences of these changes, with a particular focus on pollination services.



Get tough, get toxic or get a bodyguard

Supervised by Dr Scott Johnson and Dr Ben Moore, this Australian Research Council (ARC)-funded project aimed to: (i) integrate belowground herbivory into the optimal defence theory framework by considering various above- and below-ground chemical and physical defences against herbivory across a range of grasses, and (ii) identify the underlying reasons for different root defensive strategies employed.

Grasses are relatively tolerant of above-ground herbivory but usually also fight back using a variety of mechanisms, including:

1. Toughness (direct physical defence)

2. Toxicity (direct chemical defence)

3. Bodyguards (indirect defence via recruitment of the herbivore's enemy)

Little was known about how roots are defended against root herbivores as most research to date has focussed on above-ground defences.  We investigated the underlying reasons for the different root defensive strategies employed, with potential implications for the management of grasslands, which represent one of Australia's most threatened habitats.



Australia, Wales, Scotland, Madagascar

Get tough, get toxic or get a bodyguard

Postdoctoral Research 2016-2017

Australian Research Council grant

Hawkesbury Institute for the Environment, Australia

Silicon-based grass defences extend up the food chain

British Ecological Society small research grant 2016

Hawkesbury Institute for the Environment, Australia

The impacts of climate change and belowground herbivory on aphids via primary metabolites

Doctor of Philosophy (PhD) 2012-2016

Hawkesbury Institute for the Environment, Sydney, Australia

Determinants of invasiveness: the effects of grazing, nutrient availability, disturbance and seed-predating soil fauna on the invasion success of tree mallow, Lavatera arborea

Masters of Research (MRes) 2010-2011

Cardiff University, Wales in collaboration with The University of Aberdeen, Scotland

Population genetic diversity and differentiation in the Chinese bamboo rat (Rhizomys sinensis) using microsatellite markers

Undergraduate Final Year Research Project 2009-2010

Cardiff University, Wales

Malagasy skinks: an investigation into weather and habitat preference in the Analamazaotra Forest Station Reserve

Undergraduate Professional Training Year (PTY) 2008-2009

Association Mitsinjo, Andasibe, Madagascar




Book Chapters:


Johnson SN, Crotty FV, Ryalls JMW, Murray, PJ (2018). Belowground Experimental Approaches for Exploring Aboveground-Belowground Patterns. In: Ohgushi T, Wurst S, Johnson SN (eds) Aboveground-Belowground Community Ecology. Ecological Studies (Analysis and Synthesis), vol 234. Springer, Cham.


Ryalls JMW, Harrington R (2016). Climate and Atmospheric Change Impacts on Aphids as Vectors of Plant Diseases. In: Johnson SN, Jones TH (eds) Global Climate Change and Terrestrial Invertebrates. Oxford, UK: Wiley.

Johnson SN, Ryalls JMW, Staley JT (2016). Impacts of Atmospheric and Precipitation  Change on Aboveground–Belowground Invertebrate Interactions. In: Johnson SN, Jones TH (eds) Global Climate Change and Terrestrial Invertebrates. Oxford, UK: Wiley.



Journal articles:

Reitmayer CM, Ryalls JMW, Farthing E, Jackson CW, Girling RD,  Newman TA (2019). Acute exposure to diesel exhaust induces central nervous system stress and altered learning and memory in honey beesScientific Reports, 9, 5793.

Johnson SN, Ryalls JMW, Barton CVM, Tjoelker MG, Wright IJ, Moore BD (2019). Climate warming and plant biomechanical defences: silicon addition contributes to herbivore suppression in a pasture grass. Functional Ecology, 33, 587-596.

Ryalls JMW, Moore BD, Johnson SN (2018). Silicon uptake by a pasture grass experiencing simulated grazing is greatest under elevated precipitation. BMC Ecology, doi: 10.1186/s12898-018-0208-6.

Ryalls JMW, Moore BD, Johnson SN, Connor M, Hiltpold I (2018). Root responses to domestication, precipitation and silicification: weeping meadow grass simplifies and alters toughness. Plant and Soil, doi: 10.1007/s11104-018-3650-5.

Kremer JMM, Nooten SS, Cook JM, Ryalls JMW, Barton CVM, Johnson SN (2018). Elevated atmospheric carbon dioxide concentrations promote ant tending of aphids. Journal of Animal Ecology, doi: 10.1111/1365-2656.12842.

Johnson SN, Lopaticki G, Aslam TJ, Barnett K, Frew A, Hartley SE, Hiltpold I, Ryalls JMW  (2018). Dryland management regimes alter forest habitats and understory arthropod communities. Annals of Applied Biology, doi: 10.1111/aab.12419.

Johnson SN, Glauser G, Hiltpold I, Moore BD, Ryalls JMW (2018). Root herbivore performance suppressed when feeding on a jasmonate-induced pasture grass. Ecological Entomology, doi: 10.1111/een.12527.

Johnson SN, Ryalls JMW, Gherlenda AN, Frew A, Hartley SE (2018). Benefits from below: silicon supplementation maintains legume productivity under predicted climate change scenarios. Frontiers in Plant Science, doi: 10.3389/fpls.2018.00202.

Ryalls JMW, Hartley SE, Johnson SN (2017).  Impacts of silicon-based grass defences across trophic levels under both current and future atmospheric CO2 scenarios.

Biology Letters, doi: 10.1098/rsbl.2016.0912.

Johnson SN, Hartley SE and Ryalls JMW, Frew A, DeGabriel JL, Duncan M, Gherlenda A (2017). Silicon-induced root nodulation and synthesis of essential amino acids in a legume is associated with higher herbivore abundance. Functional Ecology, doi:10.1111/1365-2435.12893.

Ryalls JMW, Moore BD, Riegler M, Bromfield LM, Hall AAG, Johnson SN (2017). Climate and atmospheric change impacts on sap-feeding herbivores: a mechanistic explanation based on functional groups of primary metabolites. Functional Ecology, 31, 161-171.

Johnson SN, Gherlenda AN, Frew A, Ryalls JMW (2016). The importance of testing multiple environmental factors in legume–insect research: replication, reviewers and rebuttal. Frontiers in Plant Science 7, 489, doi: 10.3389/fpls.2016.00489.

Ryalls JMW, Moore BD, Riegler M, Johnson SN (2016). Above–belowground herbivore interactions in mixed plant communities are influenced by altered precipitation patterns. Frontiers in Plant Science 7, 345, doi: 10.3389/fpls.2016.00345.

Ryalls JMW, Moore BD, Riegler M, Gherlenda AN, Johnson SN (2015). Amino acid-mediated impacts of elevated carbon dioxide and simulated root herbivory on aphids are neutralized by increased air temperatures. Journal of Experimental Botany 66, 613-623.

Johnson SN, Ryalls JMW, Karley AJ (2014). Global climate change and crop resistance to aphids: contrasting responses of lucerne genotypes to elevated atmospheric carbon dioxide. Annals of Applied Biology 165, 62-72.

Ryalls JMW, Riegler M, Moore BD, Lopaticki G, Johnson SN (2013). Effects of elevated temperature and CO2 on aboveground–belowground systems: a case study with plants, their mutualistic bacteria and root / shoot herbivores. Frontiers in Plant Science 4, 445.

Ryalls JMW, Riegler M, Moore BD, Johnson SN (2013). Biology and trophic interactions of lucerne aphids. Agricultural and Forest Entomology 15, 335-350.





Ryalls JMW, Johnson SN (2017). Legume pasture pest responses to global climate change. Proceedings of the Ninth Australasian Conference of Grassland Invertebrate Ecology, pp. 117-119. Western Sydney University, Hawkesbury, NSW, Australia.


Hiltpold I, Ryalls JMW, Moore BD, Johnson SN. (2017) Recruitment of entomopathogenic nematodes toward Panicum bisulcatum roots damaged by scarab larvae. Proceedings of the Ninth Australasian Conference of Grassland Invertebrate Ecology, pp. 51-53. Western Sydney University, Hawkesbury, NSW, Australia.

Ryalls JMW, Hartley SE, Johnson SN (2016). Silicon and tri-trophic interactions. Oral presentation at the British Ecological Society Annual Meeting 2016, Licerpool, UK.

Ryalls JMW, Moore BD, Riegler M, Johnson SN (2016). Aboveground–belowground interactions. Oral & poster presentations at the Ninth Australasian Conference of Grassland Invertebrate Ecology (4-7 April 2016), Western Sydney University, Australia.

Ryalls JMW, Riegler M, Moore BD, Johnson SN (2014). How climate change mediates belowground effects on aboveground aphids in lucerne. Proceedings of the 10th European Congress of Entomology (eds P. Smithers, D. George & J. Banfield-Zanin), pp. 45-46. The Royal Entomological Society, University of York, UK.

Ryalls JMW, Riegler M, Moore BD, Johnson SN (2014). Above, Below and Beyond: how climate change mediates interactions between above- and below-ground insects on lucerne. Oral presentation at 10th European Congress of Entomology in York, UK.

Ryalls JMW., Riegler M, Moore BD, Johnson SN (2014). Above-belowground interactions in lucerne. Poster presentation at 15th International Symposium on Insect-Plant Interactions, Neuchâtel, Switzerland.

Ryalls JMW, Riegler M, Moore BD, Johnson SN (2013). How does climate change mediate belowground effects on aboveground aphids in lucerne?  Oral presentation at EcoTas13, New Zealand.

Ryalls JMW, Jones TH, Ross L, van der Wal R (2011). Determinants of tree mallow invasiveness.  Poster presentation at the British Ecological Society Annual Meeting 2011, Sheffield, UK.



British Ecological Society large research grant (£20,000) for research in ecology

"Does air pollution inhibit the recruitment of plant bodyguards?"

British Ecological Society small research grant (£5,000) for research in ecology

"Back to the future: how past, present and impending CO2 concentrations shape silicon-based defences in grasses"


E.A.Southee Award (AU$10,000) to Promote Excellence in Agricultural Research, Western Sydney University

"Future-proofing Australian lucerne against the threats of climate change and invasive pests"

Sponsorship for the Ninth Australasian Conference on Grassland Invertebrate Ecology

4-7 April 2016, Hawkesbury, Australia

Best Photograph Award at the Ninth Australasian Conference of Grassland Invertebrate Ecology 4-7 April 2016, Hawkesbury, Australia

Hawkesbury Institute for the Environment (HIE) Postgraduate Research Award

HIE 2015 Jann Conroy Award for Outstanding Student's Presentation

HIE 2015 John Cairney Award for Outstanding Student's Publication

HIE 2014 Presentation Award - People's Choice 



BBC Radio 4 Farming Today - Controlling agricultural pests


"Plants have evolved a taste for sand that deters hungry insects"

New Scientist, 15 March 2017

"Climate change may hinder plants' ability to defend against predators"

ECNS, 15 March 2017

"Plants have learned to imitate the 'taste of sand' for protection"

The Earth Chronicle of Life, 17 March 2017



Experimental images

Cicada unsuccessful emergence
Cicada unsuccessful emergence

NSW, Australia

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BBC team
BBC team

Andasibe, Madagascar

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Grass root grub
Grass root grub

Cane beetle larvae eating Microlaena root

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Sitona discoideus larva and eggs

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Rain exclusion shelters
Rain exclusion shelters

Hawkesbury Forest Experiment, Richmond, NSW, Australia

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Praying mantis
Praying mantis
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Glasshouse fun
Glasshouse fun

Hawkesbury Campus, Western Sydney University

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Aphid net
Aphid net

Lucerne surrounded by net to prevent aphid movement

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They used to fall into my pitfall traps

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