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Understanding and Managing for Native Pollinators in Almond Systems

Kitty Boltekhbolte@ucdavis.edu

Wild bee pollination at UC Davis

• Dr. Neal Williams• Wild bee contributions to crop pollination• Landscape effects on wild bee communities• Effects of habitat enhancement on bees and pollination • Plant choice for creation of bee habitat• Other impacts of pollinator enhancement, e.g.

pests/beneficial insects

Talk Overview

• What are native bees?• Why and how are native bees important to almond

pollination?• Managing orchards to support alternative

pollinators• Alternative Managed Bees: the Blue Orchard Bee• Establishing pollinator habitat to support native bees

What Are Native Bees?

• Bees that originate in CA • Does NOT include Honey Bee, which is from Europe

• ~ 1500 species of native bees in CA, ~450 in Sac Valley

Honey Bees:• 1 species• Social• Live in Hives• Produce Honey

Native Bees:• Many species • Typically Solitary• Many nest in twigs,

hollow stems, or underground

Diversity of almond pollinators

Spring bee

Digger beeBumble bee

Long horned bee

Hairy-leg bee Tiny dark beeSmall dark bee

Blue orchard bee Other mason bee

Slide credit: K Ward

Why are native bees important in an almond system?

Nut Yield and Quality

Slide credit: K Ward

Why are native bees important in an almond system?

Pollination

Nut Yield and Quality

Slide credit: K Ward

Why are native bees important in an almond system?

Number of Bees

Pollination per bee

X = Pollination

Nut Yield and Quality

Diagram: K Ward

Necessity of outcrossing

Native Bee Potential• Increasing concerns about honey bee availability and health• Synergistic effects: make honey bees more efficient pollinators• Fly in worse weather conditions

Dr. Claire Brittain

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without WBs with WBs

% fr

uit s

et p

er o

rcha

rd

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without WBs with WBs

% V

isits

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ollin

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Data C. Brittain, graph from K Ward

21% 16%

Orchard Orchard

Single visit pollination by honey bees

Fruit set

Wild bees make honey bees better pollinators

Weather conditionsNative bees and other wild pollinators willing to fly in worse weather conditions than honeybees

Data C Brittain from K Ward

Managing for native bees in your orchard: the blue orchard bee

• Exploring potential for Blue Orchard Bees as an alternative managed bee

• Can nest in man-made nesting blocks of wood or cardboard

• ~ 800-1000 BOB females needed to pollinate one acre of almonds effectively

Nest in provided blocks, which can be collected and

stored

Offspring in bee blocks mature

Winter: chill nest blocks to ensure

synchronous emergence

Warm cocoons and place into orchards for bees to emerge

Bees pollinate crop

Blue Orchard Bee Management

Cycle

Feb-March

April

April - September

Dec - JanuaryEarly Feb

Benefits of adding pollinator habitat to almond systems

• Improve nest retention for Blue Orchard Bees?

• Forage for honey bee colonies before almond bloom

• Improve honey bee nutrition and health

• Forage and nesting resources for native bees

Proportion of HB movements across vs. down the orchard rows

Key considerations

• Develop a mix that blooms at the right times (i.e. provides resources before and after almond)

• Identify plant species suitable for almond growing regions• Develop methods for establishing plantings that are cost and labor

effective

Bee visits to almond mix

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2/22/2013 3/22/2013 4/22/2013

Num

ber o

f bee

s per

plo

t

Honey bees

Wild bees

Lost Hills 1614Honey Bee 1017Native Bee 515

BLOOM

Graph: K Ward

Flower strips did not compete with almonds

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ControlRestoredWildflower strip

Mid bloom

Late bloom

Distance into orchard

Alm

ond

flow

er v

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tion

Graph: K Ward

Planning for wildflower plantingsSite considerations

• Space and time available• Proximity to crop• Management practices• Weed pressure• Exposure

Planting preparation

• Essential to control weeds prior to planting

Site preparation methods

Diagram: K Ward

Establishing wildflowers

• No cultivation is key!• At most, lightly scratch soil

prior to planting with a chain harrow

• Spread seed with a dropseederor hand-cranked seeder

• Cultipack (ring-roll) to ensure good contact with soil

Ongoing maintenance

• Be attentive to wildflowers as they begin to grow and monitor for weeds

• Control grasses with grass-specific herbicides

• Hand-pull small patches or weeds or spray with a targeted herbicide application

• Remember that broadleaf herbicides will also harm wildflowers

• Consider spraying or mowing plot perimeter

• Plot should reseed from year to year

Acknowledgements

• Researchers:• Neal Williams, Kimiora Ward, UCD• Theresa Pitts-Singer, USDA ARS• Claire Brittain, project ICP

• Growers:• Amy Abele, Mary Fahey, Pat and

Kim Gallagher, Dave and Diane Gilmer, Rachael Long, Wonderful Orchards, Muir Glen

Additional Resources

• Xerces Society: regional plant lists, pollinator habitat installation guides, etc:http://www.xerces.org/pollinator-conservation/

• USDA-ARS Blue Orchard Bee Manual: http://bit.ly/2kaVca3

• Project ICP: www.projecticp.orgkhbolte@ucdavis.edu

kiward@ucdavis.edu

Save the Date! Almond Field Day

March 22Arbuckle, CA