Attracting and Maintaining Native for Garden Pollination

Neal Williams Department of Entomology UC-Davis [email protected] PollinatorsPollinators -- keykey ecosystemecological function service

• 60-70% of all flowering plant species require it. (Axelrod 1960, Bawa 1990)

• Reproduction limited by lack of pollinators (46% - 72% of populations studied). (Ashman et al. 2006)

• 35% of primary food crops benefit from pollinators (Klein et al. 2007)

• Of 1300 crops worldwide, 70% require animal pollinators for one or more cultivars (Roubik 1995) Pollinator declines

• Lost of once common species National Research Council (2007)

• Long term decline in managed honeybees

• New and persistent diseases • Varroa Bombus occidentalis • Colony Collapse Disorder

US honey colonies Bees in urban landscapes.

• Role in gardens and urban farms – Vegetable and fruit production – Native bees have a unique role to play

• Bees do well in cities – San Francisco – bumble bees – Philadelphia – bumble bees – Tucson AZ – all species associated with certain flowers

– Characteristics of how & where they live and what they eat determine how well they do.

Bombus spp. abundance

Bumble bees more abundance at more developed sites

200

150

100

50

0 Abundance residual abundnace residual -50 r2 = 0.70

-100 y = 313.0x + 62.8

-150 0.0 0.2 0.4 0.6 0.8 proportionProportion developed developed land (2500m land radius) Honeybee Haven UC Davis

• Also supports non-Apis bees • In ½ acre: – 40 bee species – 22 genera • All common bee groups (families)

Robbin Thorp is monitoring bees Overview

• Bee biology: – diversity of bee species – the diversity of life-history – Implications for supporting pollinators in the urban landscape

• Nesting resources

• Identifying floral resources to support native pollinators

• Knowledge of bee biology–their needs–will help inform how to support their populations in gardens

Phylogeny of bee families Spheciform

Colletidae, Stenotritidae

Andrenidae, including Oxaeinae

Halictidae

Melittidae

Xylocopinae Nomadinae Eucerines Anthophines California 1,600 species Apinae USA 4,500 species Apini Bombini

Based on Danforth et al. 2006, Roig-Alsina and Michener 1993 Plasterer bees and Andrena

• • Halictids –sweat bees Megachilidae

• Leaf-cutters • Mason bees Apidae

• Dwarf carpenter bees • Carpenter bees- Xylocopa Ceratina Apidae

• and relatives • Bumble bees Bee Biology

• Life cycle • Food • Nesting

photos: José Verkest, Native bee needs

• Complementary resources:

Flowers Nest sites

Urban habitat and landscape changes

• Loss of floral resources

– Invasive species – Pavement – Lawns – Non-rewarding cultivars

• Loss of nesting sites – Pavement – lawns

• Poisoning (pesticides)

Nesting

Above ground -Twig nesting Ground-nesting

P.Westrich Cavity nesting colonies

S. Camarzine

N Williams Cleptoparasites Nesting materials

Andrej GOGALA

Westrich Other nesting requirements

• Soil type – Particle size – Salt content – Moisture • Slope • Wood density • Temperature

Anthophora plumipes Managing nesting resources

• Artificial nest sites – Bee blocks – Reed cane bundles Managing nesting resources

• Augment nest habitat – Reduce mulch – Diverse sun-shade – Nest materials

• Overwintering sites Bee Biology

• Life cycle • Food • Nesting

photos: José Verkest, Floral Resources

Bee traits • Body size – flower interactions – foraging distances – bee tongue lengths Floral Resources

• Flower traits – – Nectar • Not all horticultural varieties offer rewards • Choose some rewarding varieties

Floral Resources

• Flower traits – Diverse flower morphologies

• Continuous bloom over the season

Implications of life history for conservation in urban landscapes

Simple rules of thumb

• A diversity of flower types • Nest sites are as likely as supports a diversity of bees flower resources to limit bees

• Bees eat pollen and nectar not • Bare ground will help some, so petals don’t mulch it all.

• Flowers must be available throughout the season

Developing recommendations of floral resources for bees

• Surveying use and preference • Use versus preference –asking bees – Accounting for plant abundance – 6770 specimens – Multiple habitat types • Native plants to region – Base list – Does this matter for urban gardens?

• Check for adaptation to local conditions or conditions of interest

• Bloom duration • Reward type offered • Human attraction too. A focus on forbs

Forb species list Annual a perennial mix Annual and Perennial Mix Bloom time Lupinus succulentus Spring

Phacelia tanacetifolia Spring

Trifolium wildenovii Late Spring - Summer

Trifolium fucatum Late Spring

Trichostema lanceolatum Summer late summer

Eschscholzia californica Spring

Phacelia californica Early summer

Lupinus formosus Late Spring-Summer

Lotus scoparius Summer

Grindellia camporum Summer-Fall Hedgerow/ forb-strip restoration

Spring Late Summer

2 3 4 5 6 7 8

Flowering Season Plant Common Name Plant Scientific Name Visiting Bees Bee Preference Apri (Perennial, Annual) May June July Aug Sept l

Field thistle t Ap, B, X 1. Cirsium discolor (P) **

Daisy fleabane 2. Erigeron strigosus Ap, Au, C, H, L (A) * Helmet flower 3. Scutellaria integrifolia B (P) *** Indianhemp 4. Apocynum cannabinum An, Ap, Au, B, L (P) ** Common selfheal 5. Prunella vulgaris Ap, Au, B, L (P) ** Swamp verbena 6. Verbena hastata C (P) *** Common milkweed 7. Asclepias syriaca Ap, B, X (P) *** Flat-top goldentop 8. Euthamia graminifolia Ap, Au, C, H, L, X (P) ** Palespike lobelia 9. Lobelia spicata B, C (P) *** False foxglove 10. Agalinis purpurea Au (A) *** 11. Pycnanthemum tenuifolium Narrowleaf mountainmint (P) Ap, Au, B, C, H, L ** 12. Solidago odora Anisescented goldenrod (P) Ap, Au, C, H, L, X ** 13. Potentilla norvegica Norwegian cinquefoil (A/P) Au, H, L *** Spotted joe pye weed 14. Eupatorium maculatum B, C, H (P) ***

Broadleaf ironweed 15. Vernonia noveboracensis Au, C, H, L (P) *** References for gardeners

http://nature.berkeley.edu/urbanbeegardens/gbt.html http://www.xerces.org/pollinator-resource-center/ Simple rules of thumb

• A diversity of flower types • Nest sites are as likely as supports a diversity of bees flower resources to limit bees

• Bees eat pollen and nectar not • Bare ground will help some, so petals don’t mulch it all.

• Flowers must be available throughout the season

Bumble bees in an Urban landscape

• Study Area • 10 restored meadows with wooded periphery

• Sites spanned gradient of urban development 0.1% - 68%

• Surveyed each site 3 times; Jun-Aug 2006 Philadelphia Sampling Methods

Sampling plots • Half-hectare plots in target meadows

Bees • Net collected off flowers for 2 hour-long periods

Floral Resources • Floral counts & diversity using quadrates

Summary: Bumble bee communities and residential development

• Do restored meadows support diverse Bombus communities?

Yes, restored sites support a high percentage of local species and do so throughout the landscape

• How are diversity and richness affected by composition of the surrounding landscape?

Urban semi-natural habitats support large populations of bumble bees and represent viable locations for diversity conservation Bombus spp. richness

Bumble bee diversity invariant to landscape change

2.0 r2 = 0.04 1.5 NS 1.0 6

0.5 6 7 6 0.0 6 6 -0.5 7 7 residual species richness species residual -1.0 8 -1.5 5 -2.0 0.0 0.2 0.4 0.6 0.8 proportion developed land (2500m radius) Body size and foraging distance

20 R2 = 0.85

15 CarpenterXylocopa virginicabee

BombusBumble terrestris bee 10

MegachileLeafcutter rotundata bee 5

foraging range (km) range foraging 0

OsmiaMason corniforns bee DialictusSweat unbripennis bee -5 0 1 2 3 4 5 6 Body size IT span (mm)