Dr. Diana Bizecki Robson Curator of Botany [email protected] Introduction  Prairie restoration has focused on establishing:  grass cover;  species richness.  restoration has not received much attention.  Sustainability of restored prairies is influenced by pollinator abundance.  Financial limitations may mean that only a small number of species can be restored.  Question: Which flowering species are most important to restore? Plant-pollinator structure  Prairie plant-pollinator communities are nested.  This means that:  Most species interact with only a few others;  A few generalist species (= “core” species) interact with many others.  Generalists are essential for system functioning.  Effective ecosystem restoration probably requires inclusion of these species. Pollination network

Generalists Specialists (common) (rare)

© N.S. Fabina, 2013 Research sites  Field work at:  Fescue prairies (FPP):  NCC Elk Glen & Cleland;  Crown land.  Mixed grass prairie:  NCC Yellow Quill Prairie FPP (YQPP). BHPP  Tall grass prairies: YQPP LPM  Birds Hill Prov. Park (BHPP);  Living Prairie Museum (LPM); TGPP  Tall-grass Prairie Preserve (TGPP). Research methods  Set up monitoring plots.  Record the number of flowering stems in each plot.  From ~9:30 am to 5 pm record all insect visitors to each plant in the plot.

 Calculate insect visits per © TMM 2 stem or m . Cleland plot #2B Pollinators on prairies

Flies Short-tongued bees Long-tongued bees

Beetles & bugs Wasps & ants & © TMM Pollinator taxa 100% 90% 80% 70% & bugs 60% Butterflies & moths 50% Flies 40% Wasps & ants

Insect taxa (%) taxa Insect 30% Short-tongued bees 20% Long-tongued bees 10% 0% FPP YQPP BHPP LPM TGPP Pollinator visits 100% 90% 80% 70% Beetles & bugs 60% Butterflies & moths 50% Flies 40% Wasps & ants Short-tongued bees

Insect visits (%) visits Insect 30% 20% Long-tongued bees 10% 0% FPP YQPP BHPP LPM TGPP Bee visits 100% 90% 80% 70% Sweat bees 60% Polyester bees 50% Mining bees 40% Leaf-cutter bees Bee visits (%) visits Bee 30% Bumblebees 20% 10% 0% FPP YQPP BHPP LPM TGPP Fly visits 100% 90% 80% 70% Other 60% Parasitic flies 50% Flower flies 40% Soldier flies Fly visits (%) visits Fly 30% Muscid flies 20% Bee flies 10% 0% FPP YQPP BHPP LPM TGPP Why the difference?  TGPP is on poorly drained gleysolic soil.  LPM is on heavy, vertisolic soil  BHPP, YQPP & FPP are on well-drained, chernozemic soils.  Many bees and wasps are ground nesters and are less common on water-saturated or heavy soils.  Larval habitat availability affects which fly groups dominate. colour 100% 90% 80% 70% 60% Yellow/orange 50% White/cream 40% Purple/blue/pink 30%

20% Mean inflorescence (%) inflorescence Mean 10% 0% FPP YQPP BHPP LPM TGPP Insect visits 100% 90% 80% 70% 60% Yellow/orange 50% White/cream 40% Purple/blue/pink 30%

Total insect visits (%) visits insect Total 20% 10% 0% FPP YQPP BHPP LPM TGPP Why the difference?  Bees tend to favour cool-coloured flowers.  At sites with high bee numbers more visits to the cool- coloured flowers occur.  At sites with high fly numbers more visits to the warm- coloured flowers occur.  For restoration purposes, focus on the species that the dominant insects prefer. Generalists  Generalist plants tend to have easily accessible nectar and pollen.

 Floral tubes are typically © TMM short. Flower fly on rigid goldenrod  Many are warm-coloured.  In goldenrods are visited by the greatest variety of pollinators.

© TMM Bumblebee on rigid goldenrod Insect visitors Scientific name Taxa (#) Groups (#) Sites (#) nemoralis 88 6 All 5 Solidago rigida 75 6 All 5 glabellus 59 5 All 5 Solidago canadensis 50 6 BHPP, FPP, LPM, TGPP Zizia aptera 43 6 BHPP, FPP, LPM, TGPP Symphoricarpos occidentalis 43 6 FPP, LPM, TGPP, YQPP Campanula rotundifolia 42 5 All 5 Dalea purpurea 41 4 All 5 Rudbeckia hirta 37 4 BHPP, FPP, LPM, TGPP Heterotheca villosa 35 6 BHPP, YQPP Insect visitation rate Scientific name Visits/ Groups (#) Sites (#) stem/hr Heuchera richardsonii 4.1 2 BHPP, FPP, YQPP Solidago canadensis 4.0 6 BHPP, FPP, LPM, TGPP Cirsium drummondii 3.2 3 FPP Amorpha nana 3.1 1 LPM Solidago rigida 3.0 6 All 5 Symphyo. ericoides 2.8 5 All 5 Prunus virginiana 2.7 5 FPP Cirsium flodmanii 2.7 3 YQPP, TGPP Liatris ligulistylis 2.6 3 FPP, LPM,TGPP Agastache foeniculum 2.4 3 FPP Implications for restoration  Drier areas that are bee-dominated would benefit from more specialized flowers (e.g. zygomorphic, tubular).  e.g. Monarda fistulosa, Hedysarum boreale, Astragalus spp.  Moist or heavy clay soils that are fly-dominated would benefit from more generalist flowers.  e.g. Solidago spp.  White flowers are likely visited more at night by moths.  e.g. Polygala senega, Galium boreale? Mind the flower gaps!  Relying on total visitor taxa to select species may result in a spring “flower gap”.  Best to identify most popular plants (2-5 species) flowering each month to include in restoration seed mix. Restoration seed mix Time Mixed-grass Prairie Fescue Prairie Tall-grass Prairie Jun Geum triflorum Geum triflorum Zizia aptera^ Gaillardia aristata Prunus virginiana Zizia aurea Packera paupercula Drymocallis arguta Packera plattensis Jul Erigeron strigosus Erigeron glabellus^ Erigeron glabellus^ Dalea purpurea^ Symphor. occidentalis^ Solidago ptarmicoides Monarda fistulosa Campanula rotundifolia^ Campanula rotundifolia^ Aug Heterotheca villosa^ Solidago rigida^ Solidago rigida^ Linum lewisii Rudbeckia hirta^ Solidago canadensis^ Agastache foeniculum Liatris ligulistylis Sep Solidago nemoralis* Solidago nemoralis* Solidago nemoralis* Symphyo. laeve* Symphyo. laeve* Symphyo. laeve* Symphyo. ericoides Symphyo. ericoides Symphyo. ciliolatum Summary  Flies and bees are the most important pollinators in Manitoba.  Composition varies with moisture and soil type.  Specialist plants tend to attract long-tongued bees and butterflies.  Abundant, white-flowered plants may be important for moths! Publications  Robson, D.B. 2008. The structure of the flower-insect visitor system in tall-grass prairie. Botany 86(11): 1266-1278.  Robson, D.B. 2010. A comparison of flower-visiting insects to rare Symphyotrichum sericeum and common Solidago nemoralis (). Botany 88: 241-249.  Robson, D.B. 2013. An assessment of the potential for pollination facilitation of a rare plant by common plants: Symphyotrichum sericeum (Asteraceae) as a case study. Botany 91: 1-9.  Robson, D.B. 2014. Identification of plant species for crop pollinator habitat enhancement in the northern prairies. J. Poll. Ecol. 14(23): 238- 254.  Robson, D.B., C. Hamel & R. Neufeld. 2017. Identification of plant species for pollinator restoration in the northern prairies. J. Poll. Ecol. 21(5): 98-108.  TMM Botany blog: http://manitobamuseum.ca/main/blogs/botany/ Acknowledgments

 Thanks to Manitoba Conservation, Manitoba Naturalists Society, City of Winnipeg and the Nature Conservancy for allowing the conduct of this research on their lands.  Special thanks to Heather Flynn, Bob Wrigley, Sarah Semmler, Reid Miller & Jason Gibbs for insect identification. Any questions?

© Bill Dean

Phone: 204-988-0653 E-mail: [email protected]