Richard J. Daley College1, Biology, Chicago, IL 60632 Hope College2, Biology, Holland, MI 49423
Multitrophic Interactions are the energy links across a range of trophic levels, this can also be represented by a food chain, herbivore feeds on plant, and predator predates herbivore. In this experiment, the study of the third trophic level is necessary to better understand how herbivores and plants interact. I used tall fescue Lolium arundinaceum. As the herbivore, I used the Bird cherry-oat aphid, Rhopalosiphum padi which feeds on tall fescue and other grasses. The parasitoid Aphelinus asychis, parasitizes aphids by laying its eggs in them. The Tall Fescue is separated into three treatment groups, wild, which is infected with the fungus Neotyphodium coenophialum, novel endophyte 577, which is a strain of fungus that was isolated from tall fescue in the Mediterranean region where the grass naturally grows, then artificially inoculated into Jesup tall fescue, and E-, which lacks N. coenophialum. Since
N. coenophialum serves as a defensive mutualist, I placed 20 pots of Wild type tall fescue, 20 of 577 and 20 of E- in a semi-natural setting where both aphids and parasitoids are present, and observed the growth, aphid density and parasitoid density of the Tall Fescue over a six week course. The growth of the plants was significantly different within the three treatments. Since N. ceonophialum modifies bottom-up regulations of trophic cascades my studies show that E- had high aphid densities and greater fluctuations, Wild has low aphid densities and small fluctuations and novel strain 577 has intermediate densities and fluctuations.
[Abstract (DOC)]