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Are endophyte-mediated effects on herbivores conditional on soil nutrients?
Päivi Lehtonen1, Marjo Helander, Kari Saikkonen
1Section of Ecology, Department of Biology, University of Turku, 20014 Turku, Finland. patule@utu.fi
Oecologia
|September 8, 2004
Summary
Neotyphodium endophyte infection generally reduces herbivore performance on meadow fescue. However, this study found that increased soil nutrients worsen this effect, impacting plant fitness.
Area of Science:
- Plant-microbe interactions
- Chemical ecology
- Ecology
Background:
- Neotyphodium endophytes and grass hosts often exhibit mutualistic relationships.
- Fungal mycotoxins enhance plant resistance to herbivores, with the fungus benefiting from plant sustenance.
- Environmental factors influencing these associations are often overlooked.
Purpose of the Study:
- To investigate the impact of endophyte infection and soil nutrient availability on bird-cherry aphid performance on meadow fescue.
- To experimentally assess the interaction between endophyte status and nutrient levels in mediating herbivore-plant dynamics.
Main Methods:
- Greenhouse experiment using meadow fescue (Lolium pratense) with varying endophyte infection statuses (naturally infected E+, uninfected E-, and endophyte-free ME-).
- Plants were grown in two distinct soil nutrient levels.
- Performance of bird-cherry aphid (Rhopalosiphum padi) was evaluated on the different host plant treatments.
Main Results:
- Endophyte infection generally reduced aphid performance across nutrient levels.
- A novel finding: herbivore performance decreased on endophyte-infected (E+) plants as soil nutrient availability increased.
- Endophyte-free (ME-) plants showed improved herbivore performance in high-nutrient soils and reduced plant performance in low-nutrient soils compared to E- and E+ plants.
Conclusions:
- Endophyte infection's protective effect against herbivores can be modulated by soil nutrient availability.
- Loss of endophyte symbiosis may compromise plant fitness, particularly under varying nutrient conditions, highlighting the importance of these associations.