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

Willamette ValleyWillamette Valley

Undergraduate Researcher: Denise Undergraduate Researcher: Denise BaumannBaumann

Mentor: Dr. Sujaya RaoMentor: Dr. Sujaya Rao

Oregon State UniversityOregon State University

Summer 2003Summer 2003

Orchardgrass in Orchardgrass in the Willamette the Willamette

ValleyValley

Dactylis glomerataDactylis glomerata

Approx. 20,000 acres Approx. 20,000 acres in the Willamettte in the Willamettte ValleyValley

Seed CropSeed Crop Forage CropForage Crop

Structure of GrassStructure of Grass

Single grass plant

Seed Stalk

Tillers

Blade (leaf) Seed Head

Endophyte AssociationEndophyte Association

Single grass plant

Seed Stalk

Tillers

Fungal Stroma

Endophytic Fungi

+ +++

- --

-

- --

-

Spermatial Transfer

(Egg Deposition)

Sexual Development of the Fungus

(Egg Hatch)

(Larval Feeding)Harvest

(Pupae Formation)

Overwintering &New growth in Spring

(Adult Emergence)

Choke in orchardgrassChoke in orchardgrass((Epichloe typhinaEpichloe typhina))

Unfertilized

Fertilized Fungus

Fungal Stoma

Past ResearchPast ResearchBultman and White (midwest)Bultman and White (midwest)

Trials carried out in the wild (isolated grass Trials carried out in the wild (isolated grass plants)plants)

0-7 larvae per fungal stroma0-7 larvae per fungal stroma

63.8 % of stromata collected had 1 larva only 63.8 % of stromata collected had 1 larva only and less than 6% had >3 larvae per stromaand less than 6% had >3 larvae per stroma

Stomata with mesh bag had NO perithecia; Stomata with mesh bag had NO perithecia; uncovered stromata had 86.6 % peritheciauncovered stromata had 86.6 % perithecia

Fly is necessary for fungal fertilizationFly is necessary for fungal fertilization

HypothesisHypothesisIn this fly-fungal interaction in orchardgrass In this fly-fungal interaction in orchardgrass

in the Willamette Valley, the fly is not the in the Willamette Valley, the fly is not the sole factor for fungal fertilization.sole factor for fungal fertilization.

Objective OneObjective One

To determine whether this fly-To determine whether this fly-fungal interaction is fungal interaction is mutualistic.mutualistic.

Two treatmentsTwo treatments

1.1. Fly physically excluded, spore Fly physically excluded, spore allowedallowed

2.2. Control (no exclusion)Control (no exclusion)

1

2

3

4

5

6

7

8

9

10

Objective OneObjective One

Research Plot on Peoria Rd.

ResultsResultsTreatment % Fertilization

Exclusion (Fly Only)

56% ns

No Exclusion 69% ns

Conclusion: The fly is not necessary for fungal fertilization in agrass field setting here in the Willamette Valley.

ns = no significant difference

Objective TwoObjective Two

Surveying orchardgrass in the Surveying orchardgrass in the Willamette Valley to determine Willamette Valley to determine the presence of the fly.the presence of the fly.

Orchardgrass SitesOrchardgrass Sites

Benton Co.

Linn Co.

Lane Co.

SRCorvallis

HPLR

CH

WD

AD

KRIB

PR ND

RR3RR2

RR1

Relationship between Avg Larva/stroma and % Larval infestation

0

10

20

30

40

50

60

RR1 RR2 KR SR WD IB HP RR3 LR AD PR ND CH

Field Site

Lar

val I

nfe

stat

ion

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

Avg

Lar

/Str

om

a

Larval Infested Stroma AvgLar/stroma

ResultsResults

0-10 larvae per fungal stroma0-10 larvae per fungal stroma

49.2 % of stromata collected had 1 49.2 % of stromata collected had 1 larva/stroma and 15 % had >3 larva/stromalarva/stroma and 15 % had >3 larva/stroma

When 10 larvae were present, >90% of the When 10 larvae were present, >90% of the fertilized stroma was consumedfertilized stroma was consumed

100 % of stromata fertilized irrespective of 100 % of stromata fertilized irrespective of larval presencelarval presence

Results continued…Results continued…

% Perithecial development at 3 sites% Perithecial development at 3 sites

SR = 94% (Average of .62 larva/stroma)SR = 94% (Average of .62 larva/stroma)

CH = 97% (no fly found at this site)CH = 97% (no fly found at this site)

RR1 = 95.7% (Average of 4.16 larva/stroma)RR1 = 95.7% (Average of 4.16 larva/stroma)

In Comparison…In Comparison… Past ResearchPast Research

1.1. Stated that the fly was Stated that the fly was obligatory for fungal obligatory for fungal fertilizationfertilization

2.2. 63.8% of stromata 63.8% of stromata collected had 1 larva collected had 1 larva only and less than 6% only and less than 6% had >3 larvae per had >3 larvae per stromastroma

3.3. Without presence of Without presence of the fly 0% fungal the fly 0% fungal stroma developed stroma developed peritheciaperithecia

My ResearchMy Research

1.1. Shows that there may Shows that there may be other factors be other factors besides the fly besides the fly fertilizing the fungus fertilizing the fungus here in the Valleyhere in the Valley

2.2. 49.2% of stromata 49.2% of stromata collected had 1 collected had 1 larva/stroma and 15% larva/stroma and 15% had >3 larva/stromahad >3 larva/stroma

3.3. 100% of fungal stroma 100% of fungal stroma developed perithecia developed perithecia irrespective of fly irrespective of fly presencepresence

Final SummationFinal 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.

Future ResearchFuture Research

Preference StudiesPreference Studies Fungal host preferences by the flyFungal host preferences by the fly

Isolation trialsIsolation trials How does fertilization occur?How does fertilization occur?

Other factors of fungal fertilizationOther factors of fungal fertilization Wind, other insects, etc.?Wind, other insects, etc.?

AcknowledgementsAcknowledgements

Howard Hughes Medical Institute (HHMI)Howard Hughes Medical Institute (HHMI) Undergraduate Research Innovation, Undergraduate Research Innovation,

Scholarship, Creativity (URISC)Scholarship, Creativity (URISC)

Sujaya Rao, Jon Umble, Devorah Shamah, Sujaya Rao, Jon Umble, Devorah Shamah, Bill Pfender, Steve Alderman, Mark Bill Pfender, Steve Alderman, Mark Mellbye, Glenn Fisher, Lynn RoyceMellbye, Glenn Fisher, Lynn Royce

Orchardgrass Growers, especially James Orchardgrass Growers, especially James VanLeeuwenVanLeeuwen

Questions?Questions?