Dual regime shifts in dynamics of an invasive predator entsoc 14

Dual regime shifts in dynamics of an

invasive predator are linked to the invasion and insecticidal

control of its prey

Christine A. Bahlai1, Wopke vanderWerf2, Matthew O’Neal3, Lia Hemerik2, Douglas A. Landis1

1 Michigan State University

2 Wageningen University

3 Iowa State University

Regime shifts

Substantial, persistent changes in function of an

ecosystem function or process

Example: Zebra muscles in Great Lakes drive

dramatic shifts phytoplankton communities

Dynamics of prey can dramatically

shift the population dynamics in

predatory species

Scheffer, M., S. Carpenter, J. A. Foley, C. Folke, and B. Walker. 2001. Catastrophic shifts in ecosystems. Nature 413:591-

596.

Strayer, D. L. 2008. Twenty years of zebra mussels: lessons from the mollusk that made headlines. Frontiers in Ecology and

the Environment 7:135-141.

USGS

Population regulation in Harmonia

Knapp, A. K., et al. 2012. Past, present, and future roles of long-term experiments in the LTER Network. Bioscience 62:377-

389.

Model selection

Fit Ricker model to population

time series

Allow K and r to vary

Use AIC to determine best fit

𝑵 𝒕 + 𝟏 = 𝑵 𝒕 𝒆𝒙𝒑 𝒓 𝟏 −𝑵 𝒕

𝑲

Per capita rate of increase

Population next year

Population this year

Carrying capacity

Bruce E. Kendall, W. M. Schaffer, C. W. Tidd,

and Lars F. Olsen. The Impact of Chaos on

Science and Society (UNU; 1997; 394 pages)

19941995

1996

1997

1998

1999

2000

2001

2002

2003

2004

2005

2006

2007

2008

2009

2010

2011

2012

0.2

0.4

0.6

0.0 0.2 0.4 0.6

N(t)

N(t

+1

)

phase

A

B

C

Harmonia dynamics

0.0

0.2

0.4

0.6

1995 2000 2005 2010

YearAv

era

ge

ca

ptu

res

pe

r tr

ap

phase

A

B

C

Same r and

K?

Arrival of soybean aphid (2000) induced shift in Harmonia’s

dynamic regime

r +20%, K +40%

What caused return to previous regime after 2005?

Soybean aphid

State 2000

2001

2002

2003

2004

2005

2006

2007

2008

2009

2010

2011

2012

Michigan

Iowa

Illinois

Wisconsi

n

Low Spotty Moderate High

No aphids Widespread outbreaks

No more major

outbreaks in MI

Pesticide use

0.0000.0010.0020.0030.004

2000 2004 2008

Cyhalothrin-lambda

0.000

0.001

0.002

0.003

2000 2004 2008

Esfenvalerate

0.000

0.005

0.010

0.0150.020

2000 2004 2008

Imidacloprid

0.000

0.005

0.010

0.015

2000 2004 2008

Thiamethoxam

State

IA

IL

MI

WI

Year

kg

ac

tiv

e i

ng

red

ien

t p

er

he

cta

re

Stone, W. W. 2013. Estimated Annual

Agricultural Pesticide Use for Counties of

the Conterminous United States, 1992–

2009. U.S. Geological Survey Data Series

752:http://pubs.usgs.gov/ds/752/.

0.0000.0010.0020.0030.004

2000 2004 2008

Cyhalothrin-lambda

0.000

0.001

0.002

0.003

2000 2004 2008

Esfenvalerate

0.000

0.005

0.010

0.0150.020

2000 2004 2008

Imidacloprid

0.000

0.005

0.010

0.015

2000 2004 2008

Thiamethoxam

State

IA

IL

MI

WI

Year

kg

ac

tiv

e i

ng

red

ien

t p

er

he

cta

re

Fo

liar

Seed

ap

plie

d

Seed treatments and soybean aphid

Seed treatments: limited window of efficacy

(~40DAP)

Early season suppression leads to regional control?

Johnson, K. D., M. E. O'Neal, D. W. Ragsdale, C. D. Difonzo, S. M. Swinton, P. M. Dixon, B. D. Potter, E. W. Hodgson, and A.

C. Costamagna. 2009. Probability of cost-effective management of soybean aphid (Hemiptera: Aphididae) in North America.

Journal of Economic Entomology 102:2101-2108.

Aphid

popula

tions

Time

0 DAP 40 DAP

EIL

Aphid infestation vs pesticide use

0.001

0.002

0.003

0.004


Cyhalothrin-lambda

0.0000

0.0005

0.0010

0.0015

0.0020

0.0025

Low SpottyModerate High

Esfenvalerate

0.000

0.005

0.010

0.015

0.020


Imidacloprid

0.000

0.005

0.010


Thiamethoxam

Aphid infestation

kg

ac

tiv

e i

ng

red

ien

t p

er

he

cta

re

Conclusions

Soybean aphid is less abundant at a regional scale

since the introduction of neonicotinoid seed treatments

Harmonia dynamics are indistinguishable from their

dynamics before soybean aphid’s arrival.

Agricultural management has driven a regime shift

Implications

Neonicotinoid regulation-

a changing landscape?

Can we maintain

landscape-level

suppression of two

invasives?

Resistant soybean Rag

genes- season long

suppression

Myers, C. and E. Hill. 2014. Benefits of neonicotinoid seed treatments to

soybean production. United States Environmental Protection Agency.

http://www2.epa.gov/pollinator-protection/benefits-neonicotinoid-seed-

treatments-soybean-production.

Hallmann, C. A. et al . 2014. Declines in insectivorous birds are associated

with high neonicotinoid concentrations. Nature advance online

publication.

Blacquière, T., G. Smagghe, C. M. van Gestel, and V. Mommaerts. 2012.

Neonicotinoids in bees: a review on concentrations, side-effects and risk

assessment. Ecotoxicology 21:973-992.

Metadata

@cbahlai

Data sources: Cooperative Extension (MSU, ISU, UI, UW- aphid

scouting data)

Doug Landis, Stuart Gage, Manuel Colunga-Garcia

(MSU-ladybeetle data)

Wesley Stone (USGS- Pesticide data)

USDA-NASS (Crop production data)

https://github.com/cbahlai/LTER_Ladybeetle_Ricke

r

Acknowledgements

Data creators

J. Megan Woltz and Julia Perrone

Funding agencies