TimingisEverything:Exploring …Digital+Assets/... · Basic(Biology(of(the(Fly! •...
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Timing is Everything: Exploring Phenological Mismatch between Goldenrod and its Gall Fly Ellery Cunan, Thomas Powell, and Arthur Weis, Department of Ecology and EvoluDonary Biology, University of Toronto INTRODUCTION Climate Change and Phenological Mismatching • Many insect species are more successful when they a4ack host plants during specific stages in growth. • If insect and host plant species respond differently to climate warming, phenological mismatch could alter insect survival. • We studied impacts of phenological mismatch by experimentally manipulaAng the emergence Ame of the goldenrod gall fly (Eurosta solidaginis), which a4acks late goldenrod (Solidago al/simma). Basic Biology of the Fly • The gall fly larva induces a gall (a tumorlike growth) on goldenrod stems, where it is is supplied with food and and protected from the elements. • The mother fly oviposits an egg into the plant bud in June. Mothers live <5 days. • The egg hatches days later, aJer which the larva bore into the stem. A sphereshaped gall forms as a result. • The gall reaches final size (1230 mm) in late July/ early August. • The larva overwinters in the gall, pupates and emerges as a fly in the following May. Plant Flowering Time, Gall Size and Fly Mortality • Galls stop growing just before the plants start flowering. • Larvae in small galls are prone to a4ach by a parasitoid wasp, Eurytoma gigantea, which drills into the gall to lay its egg. • Larvae in large galls are prone to a4ack by Downy Woodpeckers Fig. 1. Adult Eurosta fly Fig. 2. Dissected gall w/ fly pupa QUESTIONS 1. How does final gall size affect fly survival? 2. How does Aming of oviposiAon and plant flowering affect final gall size? METHODS This study was done at the Koffler ScienAfic Reserve, King City, Ontario Gall size and survival • We determined the relaAonship between gall size and a4ack rates by parasitoids and woodpeckers in the 2012 generaAon. • 400 overwintering galls were collected, their diameters measured, and then dissected to determine larval fate. Emergence phenology and gall size • We extended the range emergence Ames for the 2013 generaAon using arAficial warming and refrigeraAon. • Trays of warmed, refrigerated and unmanipulated galls were placed in the field. Flies oviposited upon emergence. • Goldenrod buds were checked daily for oviposiAon scars and then monitored for gall inducAon. Gall diameters were measured twice a week. RESULTS 0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% 12 13 14 15 16 17 18 19 20 21 22 23 24 25 Rate (%) Gall Size (mm) Rate of PredaAon by Birds Rate of ParasiAsm by E. gigantea Fig. 3 Small galls were prone to parasitoid a4ack, large galls were to woodpecker a4ack. y = 0.58x + 17284.73 R² = 0.25 10Jun 15Jun 20Jun 25Jun 30Jun 5Jul 10Jul 15Jul 20Jul 25Jul 30Jul 26May 28May 30May 1Jun 3Jun 5Jun 7Jun 9Jun 11Jun 13Jun 15Jun Gall InducDon Date OviposiDon Date Fig. 4 Delaying oviposiAon by 1 day caused more than a 1/2 day delay in gall inducAon. y = 0.31x + 12910.40 R² = 0.15 0 5 10 15 20 25 30 10Jun 15Jun 20Jun 25Jun 30Jun 5Jul 10Jul 15Jul 20Jul Gall Diameter (mm) Gall InducDon Date Galls that Start Late, End Small Fig. 5 Delaying gall inducAon by 1 day caused a 1/3 mm decrease in final diameter. DISCUSSION and IMPLICATIONS • The manipulaAon extended the range in emergence Ames to over 4 weeks, compared to the typical 2.5 weeks. • Earlyinduced galls were larger, while later inducAon resulted in smaller size (see Fig 3). • Based on parasiAsm and predaAon rates on the 2012 generaAon, 2013 galls produced in the middle of the observed inducAon period should have the highest survival rates. Survival data will be taken next Spring. • In future decades, increases in mean April/May temperatures, could lead to earlier fly emergence, increasing mean gall size, and therefore decrease parasiAsm, while increasing bird predaAon. • However, effects of increased temperature on the host plant could either intensify or mute its response to the inducAon sAmulus from the larva. A shiJing plant response could come through changes in spring emergence or in August flowering Ame. NEXT STEPS? There are plans in place to extend the experiment by collecAng data on the goldenrod plants that have been planted in the heaAng arrays located on the reserve. KSR has one of a handful of heaAng arrays on the conAnent designed to simulate temperatures predicted for a half century from now. It would be interesAng to see just how drasAc the changes are to flowering seasons and life history of the goldenrod as a result of higher than normal temperatures, and what the implicaAons are to gall size and rates of gall survival. REFERENCES 1. Weis, A., Abrahamson, W., & Andersen, M. (1992). Variable selecAon on Eurosta’s gall size, I: the extent and nature of variaAon in phenotypic selecAon. Evolu/on. 46(6), 16741697. 2. Weis, A., Wolfe, C., & Gorman., W. (1989). Genotypic variaAon and integraAon in histological features of the goldenrod ball gall. American Journal of Botany. 76(10). 15411550. 3. Bode, R., Tripi, J., & Heath, J. (2013). Goldenrod guidebook: a primer on herbivorous species commonly found on Solidago spp. (1 st ed.). Ithaca, NY: Cornell. 4. Tooke, F., & Ba4ey, N. (2010). Temperate flowering phenology. Journal of Experimental Botany, 61(11), 28532862. ACKNOWLEDGMENTS A huge thank you goes out to the staff and other researching students at KSR who have lent me a hand or given me advice during different points in my project. Special thanks are due to Dr. Powell and Dr. Weis for guiding me through my research experience and for teaching me with a great deal of paAence. Thanks are also in order for the University of Toronto’s Centre for Global Change Science for organizing this opportunity for me.
Transcript of TimingisEverything:Exploring …Digital+Assets/... · Basic(Biology(of(the(Fly! •...
Timing is Everything: Exploring Phenological Mismatch between Goldenrod and its Gall Fly
Ellery Cunan, Thomas Powell, and Arthur Weis, Department of Ecology and EvoluDonary Biology, University of Toronto
INTRODUCTION Climate Change and Phenological Mismatching • Many insect species are more successful when they a4ack host
plants during specific stages in growth. • If insect and host plant species respond differently to climate
warming, phenological mismatch could alter insect survival. • We studied impacts of phenological mismatch by experimentally
manipulaAng the emergence Ame of the goldenrod gall fly (Eurosta solidaginis), which a4acks late goldenrod (Solidago al/simma).
Basic Biology of the Fly • The gall fly larva induces a gall (a tumor-‐like growth) on
goldenrod stems, where it is is supplied with food and and protected from the elements.
• The mother fly oviposits an egg into the plant bud in June. Mothers live <5 days.
• The egg hatches days later, aJer which the larva bore into the stem. A sphere-‐shaped gall forms as a result.
• The gall reaches final size (12-‐30 mm) in late July/ early August. • The larva over-‐winters in the gall, pupates and emerges as a fly in
the following May.
Plant Flowering Time, Gall Size and Fly Mortality • Galls stop growing just before the plants start flowering. • Larvae in small galls are prone to a4ach by a parasitoid wasp,
Eurytoma gigantea, which drills into the gall to lay its egg. • Larvae in large galls are prone to a4ack by Downy Woodpeckers
Fig. 1. Adult Eurosta fly Fig. 2. Dissected gall w/ fly pupa
QUESTIONS 1. How does final gall size affect fly survival? 2. How does Aming of oviposiAon and plant flowering
affect final gall size?
METHODS This study was done at the Koffler ScienAfic Reserve, King City, Ontario Gall size and survival • We determined the relaAonship between gall size and a4ack rates by parasitoids and
woodpeckers in the 2012 generaAon. • 400 over-‐wintering galls were collected, their diameters measured, and then dissected to
determine larval fate. Emergence phenology and gall size • We extended the range emergence Ames for the 2013 generaAon using arAficial warming
and refrigeraAon. • Trays of warmed, refrigerated and unmanipulated galls were placed in the field. Flies
oviposited upon emergence. • Goldenrod buds were checked daily for oviposiAon scars and then monitored for gall
inducAon. Gall diameters were measured twice a week.
RESULTS
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
12 13 14 15 16 17 18 19 20 21 22 23 24 25
Rate (%
)
Gall Size (mm)
Rate of PredaAon by Birds
Rate of ParasiAsm by E. gigantea
Fig. 3 Small galls were prone to parasitoid a4ack, large galls were to woodpecker a4ack.
y = 0.58x + 17284.73 R² = 0.25
10-‐Jun
15-‐Jun
20-‐Jun
25-‐Jun
30-‐Jun
5-‐Jul
10-‐Jul
15-‐Jul
20-‐Jul
25-‐Jul
30-‐Jul
26-‐May 28-‐May 30-‐May 1-‐Jun 3-‐Jun 5-‐Jun 7-‐Jun 9-‐Jun 11-‐Jun 13-‐Jun 15-‐Jun
Gall Ind
ucDo
n Da
te
OviposiDon Date
Fig. 4 Delaying oviposiAon by 1 day caused more than a 1/2 day delay in gall inducAon.
y = -‐0.31x + 12910.40 R² = 0.15 0
5
10
15
20
25
30
10-‐Jun 15-‐Jun 20-‐Jun 25-‐Jun 30-‐Jun 5-‐Jul 10-‐Jul 15-‐Jul 20-‐Jul
Gall D
iameter (m
m)
Gall InducDon Date
Galls that Start Late, End Small
Fig. 5 Delaying gall inducAon by 1 day caused a 1/3 mm decrease in final diameter.
DISCUSSION and IMPLICATIONS
• The manipulaAon extended the range in emergence Ames to over 4 weeks, compared to the typical 2.5 weeks.
• Early-‐induced galls were larger, while later inducAon resulted in smaller size (see Fig 3).
• Based on parasiAsm and predaAon rates on the 2012 generaAon, 2013 galls produced in the middle of the observed inducAon period should have the highest survival rates. Survival data will be taken next Spring.
• In future decades, increases in mean April/May temperatures, could lead to earlier fly emergence, increasing mean gall size, and therefore decrease parasiAsm, while increasing bird predaAon.
• However, effects of increased temperature on the host plant could either intensify or mute its response to the inducAon sAmulus from the larva. A shiJing plant response could come through changes in spring emergence or in August flowering Ame.
NEXT STEPS? There are plans in place to extend the experiment by collecAng data on the goldenrod plants that have been planted in the heaAng arrays located on the reserve. KSR has one of a handful of heaAng arrays on the conAnent designed to simulate temperatures predicted for a half-‐century from now. It would be interesAng to see just how drasAc the changes are to flowering seasons and life history of the goldenrod as a result of higher than normal temperatures, and what the implicaAons are to gall size and rates of gall survival.
REFERENCES 1. Weis, A., Abrahamson, W., & Andersen, M. (1992). Variable selecAon on Eurosta’s gall size, I: the extent and nature of variaAon in phenotypic selecAon. Evolu/on. 46(6), 1674-‐1697. 2. Weis, A., Wolfe, C., & Gorman., W. (1989). Genotypic variaAon and integraAon in histological features of the goldenrod ball gall. American Journal of Botany. 76(10). 1541-‐1550. 3. Bode, R., Tripi, J., & Heath, J. (2013). Goldenrod guidebook: a primer on herbivorous species commonly found on Solidago spp. (1st ed.). Ithaca, NY: Cornell. 4. Tooke, F., & Ba4ey, N. (2010). Temperate flowering phenology. Journal of Experimental Botany, 61(11), 2853-‐2862.
ACKNOWLEDGMENTS A huge thank you goes out to the staff and other researching students at KSR who have lent me a hand or given me advice during different points in my project. Special thanks are due to Dr. Powell and Dr. Weis for guiding me through my research experience and for teaching me with a great deal of paAence. Thanks are also in order for the University of Toronto’s Centre for Global Change Science for organizing this opportunity for me.
