The potential implications of climate change for the wheat-aphid-YDV pathosystem

biosecurity built on science

The potential implications of climate change for the wheat-

aphid-YDV pathosystem in WA: a simulation modelling study

Cooperative Research Centre for National Plant Biosecurity

Hazel Parry1,2, Darren Kriticos1,2, Jean-Philippe Aurambout3, Wendy Griffiths2,3, Garry O’Leary3, Kyla Finlay3, Piotr

Trębicki3, Paul De Barro1,2, Jo Luck2,3

1CSIRO Ecosystem Sciences 2Cooperative Research Centre for National Plant Biosecurity

3Department of Primary Industries Victoria


Wheat-aphid-YDV pathosystem

R. padi BYDV


CLIMATE CHANGE


Large scale


No risk Endangered (no change or change unknown) Transient (no change or change unknown) No risk (positive change from endangered or transient)

Climatic niche 2030 Rhopalosiphum padi

Kriticos DJ and Macfadyen S (in prep)

Presenter

Presentation Notes

Make the point that there was a significant challenge dealing with a species with a flexible life history. Sexual and asexual lifecycles, and the presence or absence of alternate hosts and climatic signals. This is also the long-term average perspective of the risks. Climate change will shift R. padi population distributions and so spatial pattern of crop risk, largely a positive change to lower risk.


Aphids-YDV-climate change

Shift in tropical agricultural zone

Warmer, drier summers Tropical agricultural zone Increased Ryegrass and wheat yield BYDV-RMV and R. maidis increase

Parry HR, Macfadyen S and Kriticos DJ (2012) Australasian Plant Pathology

Presenter

Presentation Notes

Shifts in aphid/YDV will be species specific and vary regionally.


Small scale


eCO2 and aphid fecundity Indirect impacts mediated through changes to host plant

For R. padi daily fecundity results from the project conflicted with the literature.

Xing et al. 2003.

Daily reproduction increased with eCO2 (350 vs 550 vs 700 ppm)

P. Trebici (CRC project results)

Daily reproduction decreased with eCO2 (350 vs 650 ppm)

Presenter

Presentation Notes

Complex relationships are evident from lab and field studies on increased temperature/CO2 impacts on plant-aphid-virus system.


Wheat biomass under ambient and elevated CO2 and YDV (early) infection:

laboratory and field studies

eCO2 Field: 550 ppm eCO2 Lab: 650 ppm

Field Results

Laboratory Results

Elevated CO2 increases Biomass

Early YDV infection reduces Biomass

Presenter

Presentation Notes

YDV bigger impact than CC. Is trend reflected in final graph? Elevated CO2 boosts crop yield. YDV may have a large impact on crop yield, but only when infection is early: timing is important.


Process-based, mechanistic models

Drivers

Temperature Precipitation CO2

Mechanisms

Survival Development Movement Fecundity

Outcomes

Population size and growth Age/size structure Extinction probability Emigrants


Avondale case study

Avondale

Wokalup

1. Initiation in Irrigated Pasture 2. Wind Dispersal 3. Settling in Wheat


0

1

2

3

4

5

6

0 100 200 300 400

1998 Phenostage2030 Phenostage2070 Phenostage

Avondale case study Te

mpe

ratu

re d

iffer

ence

°C

0

0.5

1

1.5

2

2.5

3

3.5

0 200 400

2030 relative to 1998

2070 relative to 1998

Day of year

Day of year

Whe

at p

heno

stag

e

1998 CO2 = 350 ppm 2030 CO2 = 450 ppm 2070 CO2 = 620 ppm

Climate Scenario CSIRO MK-3 A2 emissions

Wheat development accelerates with Climate Change


Wheat impacts

Day of year

Bio

mas

s (k

g/ha

)

Biomass Yield

Day of year G

rain

har

vest

(kg/

ha)

0

1000

2000

3000

4000

5000

6000

7000

8000

0 100 200 300 400

1998 average biomass

2030 average biomass

0

1000

2000

3000

4000

5000

6000

0 100 200 300 400

1998 Grain2030 Grain2070 Grain 2070 average

biomass

Biomass and Yield decline with Climate Change


Aphid impacts

Migrant arrivals Population dynamics

Aphid migration delayed Aphid population growth accelerates


Consequences for wheat yield

Projected percentage loss in Grain Yield 2030 and 2070 compared to 1998 with and without YDV

Impact of YDV


Consequences for YDV impact on wheat


Summary: WA case study Climate change = more rapid crop development but lower

biomass and yield, most pronounced in 2070. Climate change is projected to:

- Slow aphid population growth over-summer in grasslands - Delay aphid timing of migration - Increase aphid population growth rate in crop, leading to - Earlier alate (winged morph) formation in crop, due to density

Synchronisation issues are more important to YDV impacts on yield than the within-crop aphid population growth.

Overall, our simulations suggest YDV impacts on yield will reduce under climate change, although the potential for spread in the crop is greater.


Thank you

For more information, please email [email protected]

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The potential implications of climate change for the wheat-aphid-YDV pathosystem