Pollination Efficiencies of
Native Bees and Syrphid Flies
Tiffany Harper
Andy Moldenke
Sujaya Rao
Pollination is the transfer of pollen from the anther of a flower
to the stigma of the same or a different flower
Pollination is critical for production of many fruits and
vegetables that we consume, and plants in natural ecosystems
In the Willamette Valley, pollination is also critical for the
many crops raised for seed
Key Pollinator Agents:
• Wind, water, animals (birds, bats, insects)
• However, about 65 % of the world’s flowering plants in
natural and agricultural ecosystems are pollinated by
insects
• Insects are a very diverse group and differ in their
abilities to pollinate flowers
One factor responsible for these differences could be
the variation in their anatomical features
• Pollination researchers have typically estimated
pollination efficiency by examination of pollen loads in
honey bees and bumble bees
• However, pollen can be attached to different body parts,
like the pile (hair) on the head, thorax and abdomen.
These attached pollen grains could be critical for
pollination
Questions
Do pollinators differ in their pollination
efficiency?
•Estimation of pollen collected on various body
parts
•Characterization of pollen collected on various
body parts
Bumble bee
Syrphid fly
Order Hymenoptera
Order Diptera
H. J. Andrews Experimental Forest
Questions
Do pollinators differ in their pollination
efficiency?
•Estimation of pollen collected on various body
parts
•Characterization of pollen collected on various
body parts
METHODS
• Bumble bees and syrphids were collected in July-
August, placed in clean vials and preserved prior to
pollen analysis
• Bumble bees and syrphids were identified
• Bumble bees and syrphid flies were examined to
determine where the pollen was present
• Plants on which insects were collected were identified
• Pollen was processed using gelatin and identified with
the pollen reference collection that I prepared
Pollen collection process simple
– was done on 70°mountain
meadow slopes
Syrphids Collected
Allograpta sp. (2) (10%)
Chrysotoxum sp. (1) (5%)
Eristalishirtus sp. (6) (30%)
Fernandinea sp. (2) (10%)
Irristalis sp. (2) (10%)
Unknown (7) (35%)
Bumble bee species collected
Bombus bifarius - 7 female (9 %)
Bombus edwardsii - 11 females 1 male (15%)
Bombus melanopygus - 4 females (5%)
Bombus mixtus - 50 females 2 males (67%)
Bombus vosnesenskii - 3 females (4%)
Plants on which pollinators were caught
Syrphid flies
Bumble bees
Achillia sp.
Allium sp.
Arenaria capilarus
Calicordous sp.
Erigeron sp.
Erigonum sp.
Eriophyllum sp.
Gilia capitata
Lanatum sp.
Lupinus laxiflorus
Mimulus guttatus
Penstemon cardwelli
Penstemon procerus
Phlox diffusa
Potentilla grandulosa
Zigadenus venenosus
Calochortus subalpinus
Delphinium sp.
Erigeron sp.
Gilia capitada
Ligisticum grayi
Lupinus laxiflorus
Mimulus guttatus
Penstemon cardwali
Penstemon poreruvous
Potentilla glandulosa
Sedum sp.
Body Part
Syrphid fly
Bumble bee
Head including mouthparts
X
X
Thorax
X
X
Abdomen
X
X
Legs
X
X
Pollen basket
X
Comparison of Pollen Abundance
Number pollen grains
Syrphid fly
Syrphid fly
< 100
24%
22%
100 -1,000
43%
36%
> 1,000
33%
42%
Questions
Do pollinators differ in their pollination
efficiency?
•Estimation of pollen collected on various body
parts
•Characterization of pollen collected on various
body parts
Syrphids
100% samples mixed pollen
2-7 plant species per sample
Bumble bees
77% samples mixed pollen
1- 7 plant species per sample
Presence of host plant pollen
Bumble bee
Syrphid flies
Present
Absent
Summary
• There were many more bumble bees than syrphid flies
on flowers
• Syrphid flies and bumble bees collected pollen on other
parts of their bodies besides the pollen basket
• Syrphid flies and bumble bees differed in plants on
which they were collected
• Bumble bees collected greater quantities of pollen per
individual than syrphid flies
Conclusion
Bumble bees that visit flowers for nectar could
potentially pollinate flowers. Thus, males may
also contribute to pollination
Syrphids are FAR more effective as pollinators
than researchers have believed so far
Future Research
• Examination of pollen on bodies of other
insect visitors on flowers
• Exploration of options for integration of
pollination by syrphid flies in agricultural
systems
Special
ThankThanks
you
•Oregon State University, College of Agricultural Sciences
•HHMI
•USDA MSP
•HJ Andrews Experimental Forest
•Kevin Ahern
•Sujaya Rao
•Andy Moldenke
•Bill Stephen
•Vera Pfeiffer
•Melissa Broussard
•Sarah Maxfield-Taylor
•Kim Phillips
•Kim Skyrm