Wild Bee Abundance and Diversity in Relation to Landscapes Surrounding

Iowa Vegetable Farms

Jarrett Jensen

Introduction• Iowa vegetable farmers rely heavily on pollinators to produce

crop• Wild pollination is free but bee diversity and abundance is

declining• As a result farmers are looking for new ways to prevent this• There is also not much data on where wild bees are or how

they are being affected• The landscape on and surrounding the farms can have major

affects on the bees• We looked at the impact of landscape factors on wild bee

abundance and diversity at vegetable farms in central and eastern Iowa

Methods: Catching the Bees• Setup pan traps on each farm

• Put colored cups into the traps and filled with soapy water• Sweep net for 20 minutes on the farm• Came back to collect the colored cups after a 24 period• Repeated this process every 2 weeks

Methods: Processing Bees• Removed the bees from the cups and washed with water and

ethanol• Dried the bees with a hairdryer• Pinned the bees • Identified the bees

Methods: GIS/GPS• Mapped out each farm using GIS program and was able to

identify the surrounding landscape of each farm• Used the GPS to define the landscape that was on each farm• Used GIS program to calculate landscape percentages both

within the farm boundary, and within a 1-km radius of the farm (the approximate foraging distance of large bees)

GIS/GPS

Results• Total number of Bees caught = 809

• 7 different families

• 10 different farms(5 in the Des Moines area, 3 in Iowa City Area, 2 North of Cedar Falls Area)

• 3 different collections from each farm

Results

10 20 30 40 50 60 70 80 90 1000

50

100

150

200

250

Farm 1

Farm 2

Farm 3

Farm 4

Farm 5

Farm 6

Farm 7 Farm 8

Farm 9

Farm 10

Total Number of Bees vs. Percent of Natural Landscape on the Farm

Percent of Natural Landscape on Farm

Tota

l Num

ber o

f Bee

s

Results

0 5 10 15 20 25 30 35 40 450

50

100

150

200

250

Farm 1

Farm 2

Farm 3

Farm 4

Farm 5

Farm 6

Farm 7 Farm 8

Farm 9

Farm 10

Total Number of Bees vs. Percent of Natural Landscape Surrounding Farm

Percent of Natural Landscape Surrounding Farm

Tota

l Num

ber o

f Bee

s

Results

Conclusions• The more natural landscape on each farm seemed to favor

wild bee abundance• Natural landscape surrounding the farms did not seem to have

a significant effect on wild bee abundance• Wild bee abundance can still flourish with low natural

landscape surroundings• This is especially important for farmers in Iowa because of the

corn and soybean fields

Conclusions• Higher percentage of natural landscape on the farm seemed

to favor a greater wild bee diversity• The types of bees found varied from farm to farm with some

of the farms being dominated by very distinct types of bees

Acknowledgements

• Thank you to Andrew Ridgway, Ai Wen, and Kenneth Elgersma for mentoring me through this entire project and to Ben Nettleton for helping with bee collection and identification.

• Funding was made possible by the National Science Foundation and Iowa EPSCoR.

• This opportunity was made possible by the Department of Biology at the University of Northern Iowa and their Summer Undergradate Research Program.