This document summarizes the effects of agricultural intensification on entomological systems in Iowa. It notes that historically 80% of Iowa was tallgrass prairie but now less than 0.1% remains, with 86% of the state classified as farmland, mostly cropland. While corn and soybeans do not require insect pollination, bees are still present and can increase soybean yields. However, widespread use of neonicotinoid insecticides from seed treatments exposes pollinators like honey bees to pesticides. Studies have found honey bee hives lose weight after soybean bloom in Iowa. Research also aims to practice both crop production and conservation through projects adding prairie strips to crop fields,

1. Consequences from
agricultural intensification and
preventative pest management:
an entomological perspective
Matt O’Neal
Department of Entomology
Iowa State University

2. Global consequences of land use
Foley et al. 2005.

3. Prairie covered Iowa before European
settlers arrived.
Historically ~80% of Iowa was a tallgrass prairie ecosystems.
Now less than 0.1% of native vegetation remains in patches.
(Samson and Knopf 1994, Smith 1998)

4. Iowa landscape dominated by
annual crop production.
Source: 2002 NLCD
86% of Iowa is classified as “farmland” by USDA;
85% of that is “cropland”
2014 = 10.1 mil. acres soybean + 13.6 mil. acres corn

6. Are bees in corn and soybean fields?

7. Neither require insect pollination, but…
Soy is a source of nectar
•Ellis 1998
•Westphal et al. 2003
Corn is a source of pollen
•Keller et al. 2005
•Westphal et al. 2003

8. Neither require insect pollination, but…
Solitary & social bees may
increase soybean yield
•Milfont et al. 2013
40+ species of bees found in
Iowa soybean fields
•Gill and O’Neal 2015

9. Large-scale deployment of seed treatments has
driven rapid increase in use of neonicotinoid
insecticides and preemptive pest management in
US field crops. Douglas and Tooker 2015.

10. Multiple routes of pesticide exposure for honey
bees living near agricultural fields.
Krupke et al. 2012
http://louisianacrops.com/wp-content/uploads/2013/03/Corn-Seed-Treatment.jpg
• Dust from seed-applied neonicotinoid
insecticides contribute to honey bee mortality.
By Muhammad Mahdi Karim (www.micro2macro.net)

11. Beekeeping in an intensive agricultural
landscape (i.e. Iowa)

12. Honey bee hives lose weight
after soybean bloom*
Early-Bloom
Mid-Bloom
Late-Bloom
Post-Bloom
to
Senescence
Average (+SEM) hive (n = 26) weight change (kg)
-4 -2 0 2 4 6 8 10 12
8 August to 13 September
22 July to 8 August
8 July to 22 July
24 June to July 8th
* Adam Dolezal et al. unpublished data

13. “In the summer of 2014…, colony losses
surpassed winter losses...”
Honey bee colony loss survey-
Bee Informed Partnership

14. Can we practice
PRODUCTION & CONSERVATION
at the same time?

15. STRIPS:
Science-based Trials of Row-crops with Prairie Strips
Lisa Schulte Moore, Matt Helmers,
J. Arbuckle, Pauline Drobney, Mary Harris, Randy
Kolka, Matt Liebman, Jeri Neal,
Matt O’Neal, and John Tyndall & others
Funded by:
THE MCKNIGHT
FOUNDATION

16. Stiff, upright stems don’t lay flat in a
pounding rain storm.

17. 100% no-till crops
90% no-till crops:
10% prairie 100% prairie
Photo: Jose Gutierrez

18. Prairie buffer strip in corn, 2010.
18

19. Native plant
wild strawberry  
golden alexanders  
Canada anemone  
penstemon  
angelica  
cow parsnip  
sand coreopsis  
shrubby cinquefoil  
Indian hemp  
late figwort  
swamp milkweed  
Culver's root  
yellow coneflower  
nodding wild onion  
meadowsweet  
yellow giant hyssop  
horsemint  
Missouri ironweed  
cup plant  
pale Indian plantain  
boneset  
blue lobelia  
pale-leaved sunflower  
Riddell's goldenrod  
New England aster  
smooth aster  
Natural
enemies AugMay Jun Jul Sep Oct
Bloom period
Bees
KEY
good
better
best
Also at: www.nativeplants.msu.edu
Visitation by wild and managed bees (Hymenoptera: Apoidea) to
eastern US native plants for use in conservation programs.
Tuell et al. 2008.

20. Prairie: a pollinator refuge*
3
0
1
2 (a) 2009
pollinators(95%CI)percatchment Prairie Crop
(b) 2010
*
*
*
100% Crop80% Crop
+
20% in
Prairie strip
90% Crop
+
10% in
Prairie strip
90% Crop
+
10% Prairie
at base of watershed
Averagepollinatorsperhabitat(+SEM)
*Schulte et al. in prep

21. Where to go from here?
• Agricultural intensification is occurring in 2 ways:
– Increased acreage for annual crop production;
– Increased pesticide use.
• Small additions of perennial habitat can have multiple
benefits.
– Use native perennial, flowering, plants.
• Place habitat in locations to maximize benefits.
– Consider STRIPS as a model (www.prairieSTRIPS.org)
– https://www.youtube.com/watch?v=Fo13YXQY-QI

22. Acknowledgements
• Collaborators: Drs. Adam Dolezal and Amy Toth
• Former students: Kelly Gill, M. Joe Wheelock, A. Varenhorst
• Graduate students: Ashley St. Clair, Ge Zhang
• Funding sources: United Soybean Board & Leopold Center for
Sustainable Agriculture
STRIPs Project
Partners: USDA Agricultural Research Service, USDA Natural
Resource Conservation Service, US Fish & Wildlife Service, US
Forest Service, farmers, landowners, stakeholder group & many,
many more
Funders: IDALS, ISU College of Agriculture & Life Science, Leopold
Center, McKnight Foundation, NSF, USDA FSA, USDA NIFA, USDA
SARE, US Forest Service, Walton Family Foundation

24. Sediment removal by prairie filter strips in row-cropped
ephemeral watersheds.
Helmers et al. 2012. J. Environ Quality 41: 1531-1539.

26. Changes in environmental impacts of major
crops in the US. Yang and Suh. 2015
“Changes in …life cycle freshwater ecotoxicity impact per ha over the past decade, expressed in
comparative toxic units (CTU), a measure of the potentially affected fraction of species
integrated over time and volume per unit mass of a chemical emitted.”

27. Soybean pests in the midwest USA-
After 2000
Soybean aphid (Aphis glycines) invasion

28. 130-fold increase in insecticide use to
soybean since the soybean aphid
arrived in the US.
(Ragsdale et al. 2011)

29. Which is the aphid-resistant variety?
(left, right, can’t tell)

30. -8
-7
-6
-5
-4
-3
-2
-1
0
1
2
Susceptible Rag1 Rag2
Yield,bushelsperacre(±SEM)
NS
Aphid resistance protects soybean
without insecticides
Rag1+2
McCarville et al. 2014
(Untreated–AphidFree)
* = Significant loss without insecticide
*
*
*

31. The good news
Aphid resistant soybeans can replace insecticides.
>
$6-$25/acre ~$10/acre
+
<$1.00*
The bad news
*Currently only available in certified organic seed.

32. So what?
• Can support/pressure be applied to
agribusiness to:
– Discourage pre-emptive insecticide use,
– Adopt pest-resistance varieties (even for minor
pests),
– Diversify landscape.

34. Photo: Drake Larsen
Spring 2013
ISU Farm

35. Remembering the Past