A Multitrophic Interaction between a Fly, a Fungus and Orchardgrass in the Willamette Valley

1. A Multitrophic Interaction between a Fly, a Fungus and Orchardgrass in the Willamette Valley Undergraduate Researcher: Denise Baumann Mentor: Dr. Sujaya Rao Oregon State University Summer 2003

2. Orchardgrass in the Willamette Valley • Dactylis glomerata • Approx. 20,000 acres in the Willamettte Valley • Seed Crop • Forage Crop

3. Blade (leaf) Tillers Seed Stalk Single grass plant Structure of Grass Seed Head

4. Endophyte Association Fungal Stroma Tillers Seed Stalk Endophytic Fungi Single grass plant

5. + + + + - - - - - - - - Sexual Development of the Fungus (Egg Hatch) Spermatial Transfer (Egg Deposition) Overwintering & New growth in Spring (Adult Emergence) (Larval Feeding) Harvest (Pupae Formation)

6. Choke in orchardgrass(Epichloe typhina) Fungal Stoma Unfertilized Fertilized Fungus

7. Past Research Bultman and White (midwest) • Trials carried out in the wild (isolated grass plants) • 0-7 larvae per fungal stroma • 63.8 % of stromata collected had 1 larva only and less than 6% had >3 larvae per stroma • Stomata with mesh bag had NO perithecia; uncovered stromata had 86.6 % perithecia Fly is necessary for fungal fertilization

8. Hypothesis In this fly-fungal interaction in orchardgrass in the Willamette Valley, the fly is not the sole factor for fungal fertilization.

9. Objective One • To determine whether this fly-fungal interaction is mutualistic. • Two treatments • Fly physically excluded, spore allowed • Control (no exclusion)

10. 1 9 8 10 2 3 7 4 6 5

11. Objective One Research Plot on Peoria Rd.

12. Results ns = no significant difference Conclusion: The fly is not necessary for fungal fertilization in a grass field setting here in the Willamette Valley.

13. Objective Two • Surveying orchardgrass in the Willamette Valley to determine the presence of the fly.

14. LR HP CH SR Corvallis Benton Co. WD LinnCo. ND PR AD IB KR RR3 RR2 Lane Co. RR1 Orchardgrass Sites

16. Results • 0-10 larvae per fungal stroma • 49.2 % of stromata collected had 1 larva/stroma and 15 % had >3 larva/stroma • When 10 larvae were present, >90% of the fertilized stroma was consumed • 100 % of stromata fertilized irrespective of larval presence

17. Results continued… % Perithecial development at 3 sites • SR = 94% (Average of .62 larva/stroma) • CH = 97% (no fly found at this site) • RR1 = 95.7% (Average of 4.16 larva/stroma)

18. Past Research Stated that the fly was obligatory for fungal fertilization 63.8% of stromata collected had 1 larva only and less than 6% had >3 larvae per stroma Without presence of the fly 0% fungal stroma developed perithecia My Research Shows that there may be other factors besides the fly fertilizing the fungus here in the Valley 49.2% of stromata collected had 1 larva/stroma and 15% had >3 larva/stroma 100% of fungal stroma developed perithecia irrespective of fly presence In Comparison…

19. Final Summation It appears the fly benefits from this interaction in the Willamette Valley; however it is unclear whether there is a positive or negative effect on the fungus.

20. Future Research • Preference Studies • Fungal host preferences by the fly • Isolation trials • How does fertilization occur? • Other factors of fungal fertilization • Wind, other insects, etc.?

21. Acknowledgements • Howard Hughes Medical Institute (HHMI) • Undergraduate Research Innovation, Scholarship, Creativity (URISC) • Sujaya Rao, Jon Umble, Devorah Shamah, Bill Pfender, Steve Alderman, Mark Mellbye, Glenn Fisher, Lynn Royce • Orchardgrass Growers, especially James VanLeeuwen

22. Questions?