| Title: | Plant silicon application alters leaf alkaloid concentrations and impacts parasitoids more adversely than their aphid hosts |
| Author(s): | Hall CR; Rowe RC; Mikhael M; Read E; Hartley SE; Johnson SN; |
| Address: | "Hawkesbury Institute for the Environment, Western Sydney University, Richmond, NSW, Australia. Casey.Hall@westernsydney.edu.au. Hawkesbury Institute for the Environment, Western Sydney University, Richmond, NSW, Australia. School of Medicine, Western Sydney University, Campbelltown, NSW, Australia. Agriculture Victoria, Centre for AgriBioscience, AgriBio, Bundoora, VIC, 3083, Australia. Department of Animal and Plant Sciences, University of Sheffield, Sheffield, S10 2TN, UK" |
| DOI: | 10.1007/s00442-021-04902-1 |
| ISSN/ISBN: | 1432-1939 (Electronic) 0029-8549 (Linking) |
| Abstract: | "Grasses accumulate large amounts of silicon (Si) which acts as a highly effective physical defence against insect herbivory, however recent evidence shows that Si supplementation also modifies plant secondary metabolite concetrations. Changes in plant secondary metabolites concentrations can have cascading effects on higher trophic levels, such as parasitoids, as they are dependent on the host herbivore for growth and development. However, relatively little is known about how Si application affects higher trophic levels. We examined the effects of Si addition on alkaloid content in leaves of Phalaris aquatica (Poaceae) and the effect on interactions between an aphid (Rhopalosiphum padi) and its parasitoid (Aphidius colemani). Si supplementation had no effect on aphid abundance or parasitism rate. Adult aphids, aphid mummies (parasitised aphids) and the emergent parasitoids were, however, significantly smaller on Si+ plants. Parasitoid traits (size and emergence) were correlated with aphid mummy size. Si addition reduced parasitoid emergence rate and size due to reduced host mummy size, in addition, significantly fewer females emerged from mummies on Si+ plants. Aphid infestation significantly altered alkaloids concentrations, reducing gramine by 80% while increasing tryptamine by 91% in Si- plants. Si addition reduced aphid-induced tryptamine concentrations by 64% and increased 5-MeO-tryptamine by over 800% in control and 142% in aphid infested plants. Our results show that while Si addition has modest impacts on the herbivore, it significantly alters secondary metabolites and has stronger effects on the higher trophic level through changes in the quality of the parasitised host" |
| Keywords: | *Alkaloids Animals *Aphids Female Host-Parasite Interactions Plant Leaves Silicon *Wasps Alkaloids Aphids Parasitoids Plant defence Silica Tri-trophic interactions; |
| Notes: | "MedlineHall, Casey R Rowe, Rhiannon C Mikhael, Meena Read, Elizabeth Hartley, Sue E Johnson, Scott N eng FT170100342/Australian Research Council/ Germany 2021/05/01 Oecologia. 2021 May; 196(1):145-154. doi: 10.1007/s00442-021-04902-1. Epub 2021 Apr 30" |
