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

Order Hymenoptera

Syrphid fly

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

Allograpta sp. (2) (10%)

Chrysotoxum sp. (1) (5%)

Eristalishirtus sp. (6) (30%)

Fernandinea sp. (2) (10%)

Irristalis sp. (2) (10%)

Unknown (7) (35%)

Syrphids Collected

Bumble bee species collectedBombus 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

Achillia sp.Allium sp.Arenaria capilarusCalicordous sp.Erigeron sp. Erigonum sp.Eriophyllum sp.Gilia capitata Lanatum sp.Lupinus laxiflorusMimulus guttatus Penstemon cardwelliPenstemon procerusPhlox diffusaPotentilla grandulosa Zigadenus venenosus

Calochortus subalpinusDelphinium sp.Erigeron sp.Gilia capitadaLigisticum grayiLupinus laxiflorusMimulus guttatusPenstemon cardwaliPenstemon poreruvousPotentilla glandulosaSedum sp.

Syrphid flies Bumble bees

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 pollenBumble beeSyrphid 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

Thank youSpecial Thanks

•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