An Elevation and Drainage Comparison of Predation by Syrphid Flies on Willow Leaf Beetles By: REU Kallin Tea

To right: white mountain research station at sunset

Outline Introduction

• High Elevation, Life History of Critters

Experimental Design• Location of Study Sites

Materials and Methods• Choosing Sites, Monitoring

Results• What Happened?

Discussion• What it all Means?

IntroductionHigh Elevation

1800-3600 meters Lower Partial Pressure of Oxygen Cooler Temperatures

Photo by:Mark Shelp

Chrysomela aeneicollis Found in Eastern Sierra

Nevada – 2500-3300m– Cool, Moist Areas

Natural History well studied– Life stages from egg, larva,

to adult Specialist on Willow

Leaves– Salicylic Acid– Larva produce toxins

Parasyrphus melanderi Found extensively in North-Western Canada and California

– 2500-3300m Specialist Predator of C. aeneicollis

– Consumes eggs and larvae

http://www.wmrs.edu/people/BIOs/john%20smiley/beetle_project/CNPStalk_files/frame.htm

Experimental Design- 3 Drainages Rock Creek

– Heart Lake, Mosquito Flat, Pine Grove– 3190m, 3111m, 2837m

Bishop Creek (South Fork)– Pipeline, S.L. Parking Lot, La Hupp– 3131m, 2996m, 2854m

Big Pine Creek (North Fork)– Upper Site, Pond Bog, Falls Site– 3229m, 3128m, 2997m

Materials and Methods Why these Sites?

– Willow Groves– Previous Surveys, – Data Loggers

Egg Clutch Marking–All Field Work–How many clutches per site?

Follow-up

Experimental Design- Study Sites Rock Creek

– Heart Lake, Mosquito Flat, Pine Grove– 3190m, 3111m, 2837m

Bishop Creek (South Fork)– Pipeline, S.L. Parking Lot, La Hupp– 3131m, 2996m, 2854m

Big Pine Creek (North Fork)– Upper Site, Pond Bog, Falls Site– 3229m, 3128m, 2997m

ResultsDrainage Differences?

0%Big Pine

Creek

71%South Lake

30%Rock Creek

Statistically Significant P-value < 0.0001

Yes!Flies Not Found in Big Pine

Creek

0

10

20

30

40

50

60

70

80

South Lake Rock Creek Big PineCreek

% F

lies p

resen

t in

Beetl

e c

lutc

hes

Elevation Differences? Fly Predation in relation to Elevation

n= 6 in statistical analysis

NoNo

Comparing Fly Presence to Elevation

y = -0.0039x + 12.743

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

2800 2900 3000 3100 3200 3300

Elevation

Avera

ge #

Fly

Eggs p

er

Clu

tch

AVERAGE # OF SYRPHI DEGGS

Linear (AVERAGE # OFSYRPHI D EGGS)

Why differences amongst drainages? Difference in Egg Clutch Size? NoNo

-Averages 41 Eggs per Clutch

Egg Clutch Size

0

5

10

15

20

25

30

35

40

45

50

South Lake Rock Creek Big Pine Creek

Drainage

# E

gg

s p

er

Clu

tch

Egg clutch size

Average clutch size at 41

Does Fly Presence Kill?

25% Survival w/ Flies

45% Survival w/o Flies

Lower Survival of Egg Clutches with Flies

y = -5.6507x + 45.269

0

20

40

60

80

100

120

0 2 4 6

# of Fly eggs present in beetle egg clutches

% B

eetl

e S

urv

iva

P-value < 0.05

YesYes

Bishop Creek:

Overall Survival Difference? 40% Average Survival

– 42.4% Big Pine Creek– 39.1% South Lake– 38.6% Rock Creek

NoNo

Same Average Beetle Survivability

0

10

20

30

40

50

South Lake Rock Creek Big Pine Creek

% B

ee

tle

su

rviv

al

surv.

Average Survival at 40

Discussion

Intuitively– If Fewer Fly Predators in Big Pine Creek, – Then More Survival of Beetle Eggs

Possible Explanations– Lower Hatching Percentage– Higher Threat by other Predators (mites,

ants)– Higher Occurrence of Cannibalism

Discussion

Nature is Complex and Sophisticated in Design– Balance

Understand it better . . . – Continue Studies in Future

THANK YOU!Wise, and Wacky Mentors

Prof. Elizabeth Dahlhoff

Prof. Nathan Rank

Humble Advisors

Dr. Eric Berlow

Dr. John Smiley

Thanks to all of WMRS Staff, who makes it all possible

And . . .

The INTERNS!