Graduated PhD 2023
Beyond physical resistance: novel aspects of plant silicon defences against arthropod herbivores
Silicon (Si) fertilisation has received increasing recognition in recent years for ameliorating biotic stresses in plants, including damage by insect herbivores. Si defences are mostly effective against chewing insects as silicification makes plant tissues abrasive and tougher, whereas sap-feeding insects are thought to be less affected. There are still substantial knowledge gaps regarding the effects of Si on direct and indirect (i.e. whereby plants benefit from natural enemies of herbivores) plant defences against herbivorous arthropods. Furthermore, it is unknown how insect anti-predator defences (e.g. cryptic colouration, immunity) are affected when feeding on Si-rich diets and whether Si mediates interactions (e.g. competition, facilitation) between insect herbivores of different feeding guilds. Using plants with contrasting capacity to accumulate Si (i.e. low, moderate and high Si-accumulators) and pest herbivores from different feeding guilds (i.e. chewing, sap-feeding and cell-content feeding), this project explores some novel facets of plant Si defences against herbivorous pests with particular emphasis on the global insect herbivore Helicoverpa armigera.
Figure 1 The overarching objective of this project is to explore how Si impacts the direct and indirect plant defences against pest herbivores (1 & 2) and to assess the plant-mediated effects of Si on insect anti-predator defences and interspecific interactions between insect herbivores (3 & 4).
Islam T, Moore BD, Johnson SN, (2023) 'Silicon fertilisation affects morphological and immune defences of an insect pest and enhances plant compensatory growth', Journal of Pest Science, vol.96, pp 41-53
Johnson SN, Barton CVM, Biru FN, Islam T, Mace WJ, Rowe RC, Cibils–Stewart X, (2023) 'Elevated atmospheric CO2 suppresses silicon accumulation and exacerbates endophyte reductions in plant phosphorus', Functional Ecology, vol.37, no.6, pp 1567 - 1579
Islam T, Moore BD, Johnson SN, (2022) 'Plant silicon defences reduce the performance of a chewing insect herbivore which benefits a contemporaneous sap-feeding insect', Ecological Entomology, vol.47, pp 951-958
Islam T, Moore BD, Johnson SN, (2022) 'Silicon suppresses a ubiquitous mite herbivore and promotes natural enemy attraction by altering plant volatile blends', Journal of Pest Science, vol.95, no.1, pp 423-434
Biru FN, Islam T, Cibils‐Stewart X, Cazzonelli CI, Elbaum R, Johnson SN, (2021) 'Anti‐herbivore silicon defences in a model grass are greatest under Miocene levels of atmospheric CO2', Global Change Biology, vol.27, pp 2959-2969
Islam T, Moore BD, Johnson SN, (2020) 'Novel evidence for systemic induction of silicon defences in cucumber following attack by a global insect herbivore', Ecological Entomology, vol.45, pp 1373-1381
Associate Professor Scott Johnson, Associate Professor Ben Moore