Dr. Diana Bizecki Robson Curator of Botany [email protected] Introduction Prairie restoration has focused on establishing: grass cover; plant species richness. Pollinator 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) Plants (rare) © N.S. Fabina, 2013 Pollinators 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 Butterflies & moths © TMM Pollinator taxa 100% 90% 80% 70% Beetles & 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. Inflorescence 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 Manitoba goldenrods are visited by the greatest variety of pollinators. © TMM Bumblebee on rigid goldenrod Insect visitors Scientific name Taxa (#) Groups (#) Sites (#) Solidago nemoralis 88 6 All 5 Solidago rigida 75 6 All 5 Erigeron 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^ Liatris punctata 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 (Asteraceae). 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].