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The blue orchard bee:
A native managed pollinator
Christelle Guédot
Department of Entomology
Most important insect pollinators: Bees
1. Feed on nectar and pollen
2. Pollen collecting structures (scopa, corbicula)
3. Display floral constancy (strong tendency to visit flowers of the
same type on a single foraging trip): important for pollination
because minimizes pollen wastage and stigma clogging with
pollen from other species
Andrena
Osmia bicornis
Jeremy Early
Wikimedia Commons
http://www.naturesdesktop.com/images/wallpapers/1600x120
0/insects/bee-collecting-pollen.jpg
John B. Pascarella, Sam Houston
State University
pollinator.info
Why are bees important?
Whole foods and Xerces Society "Share the Buzz" campaign (2013)
Bees
• At least 25,000 known species of bees
• Social vs. solitary, 90% being solitary
• ~4,500 of solitary spp. in North America
• Wisconsin: ~390 spp. (Wolf and Ascher, 2008)
Stephen Buchmann
Smallest North American bee (Perdita
minima) on largest female carpenter bee
Native
Exotic
T'ai Roulston,
University of Virginia
Bees: distinguishing characteristics
Bees
Robust
Hairy
Flat rear legs
Feed on nectar and pollen
vs.
mommammia Flickr
Wasps
Slender
Smooth
Slender legs
Predators
James Cane
Life cycle of a solitary bee
Mining bee (Andrena sp.): a year
in its underground nest as egg,
larva, and pupa before emerging to
spend a few weeks as an adult.
Photos: Dennis Briggs
Ground-nesting solitary bees
~70% of native bee species nest underground
• Resemble ant-nests from above ground
• Nests may be as deep as 3’
Photos: Eric Mader, Matthew Shepherd, Dennis Briggs
Cavity-nesting solitary bees
~30% of native species nest in cavities
•Nest in hollow plant stems, old beetle borer holes,
man-made cavities
•Nest have tunnel partitions constructed of mud,
leaf pieces, or sawdust
•Artificially managed for some crops
Photos: Edward Ross, Darrin O’Brien, Matthew Shepherd
Bees for fruit tree pollination
Impediments to bee pollination on fruit trees
- Early season; bad weather
- Short flowering period: 2-3 weeks
- Flowers receptive only few days
Christelle Guédot, UW-Madison
- Cool temperatures slow pollen germination
ovules might degenerate before fertilized
- Incompatibility: bees must move between inter-compatible
cultivars in different rows
Flower morphology
♀ organ
♂ organ
≡ Pistil
Apple pollination
• Pollinate king blossoms (first to open, produces larger fruit)
• Pollinate blossoms with large amount of compatible pollen for
high number of seeds, which relates to fruit size and shape
• Size of fruit affected by number fruit produced; thinning might
be required
http://appleharvester.blogspot.com/2011/05/king-blossom.html
Christelle Guédot, UW-Madison
The blue orchard bee
• Osmia lignaria, a native
• Solitary but gregarious
• Nest in pre-existing cavities
• Only females provision nest
• Collect nectar and pollen for provision
• Collect mud for nesting material
Back
Front
Egg
Cell1
Mud partitions
Provision
The blue orchard bee
Females
Male Female
0.4 - 0.6” long
Prepupa
instar larva
inside coccon
5th
White pupa
Black pupa
Adult
Life cycle of blue orchard bee
Eggs hatch, larvae grow
into pupae
Late
March
April - May
June
July - Aug
Sept - March
Dormant adults
Identifying females vs. males
Males smaller
than more
robust females
Males have
longer, more
slender antennae
Males do not
have scopa,
females do
Males have
more facial hair
http://seabrookeleckie.com/
Life history
• Fecundity: 10 - 20 eggs / nesting female (2.5 - 6 ♀ eggs)
• Longevity adult females: ~20 days
• Females build ~ 2-4 nests in lifetime
• Emergence:- males emerge 24-48 hrs after warming
- females emerge 1-3 days later
Why the blue orchard bee?
discoverlife.org: Osmia lignaria distribution
• Native
• Commercial use in 1970’s
• Forages in cool weather > 54°F
Designed by The Polistes Corporation
• Visits many tree species:
almonds, apple, pear, cherry, apricot,…
Why the blue orchard bee?
Foraging behavior and pollination effectiveness
% Stigma contact
Christelle Guédot, UW-Madison
http://www.ars.usda.gov/Research/docs.htm
?docid=18333
Almond
Apple
Pear
Osmia
98.7
97.7
98.7
Apis (P)
67.3
-
51.8
Apis (N)
39.5
32.7
19.0
Why the blue orchard bee?
• Blue orchard bees readily move from tree to tree and row to
row
• Facilitate cross-pollination, rather than pollination within a tree
or within a cultivar
• Preference for fruit tree pollen: 85-100%
Dandelion
http://www.swcolorado
wildflowers.com
Golden currant
Why the blue orchard bee?
Active at low light levels and low temperatures
• 33+ hours foraging in 5 days
• 15+ hours by honey bees
Usual foraging range: 300-600 ft
Max. foraging range: 1,300 ft
Homing ability: 4,000 ft
Apple yield with blue orchard bee
Commercial Apple Orchard, Utah
Apple yield (bushel)
1977 + 1978
Honey Bee
1979 + 1980
Blue orchard bee
McIntosh
4380
5186
Red Delicious
986
3248
Golden Delicious
204
288
Jonathan
430
417
Rome
184
307
Total
6184
9446
Apple Variety
53% increase
Why the blue orchard bee?
Commercial cherry orchard, Utah
Year
Pollinator
Cherry yield (Kg)
♀ BOB increase
1992
Honeybee
-
-
1993
Honeybee
3,040
-
1994
Honeybee
5,545
-
1995
Honeybee
4,820
-
1996
Honeybee
3,695
-
1997
Honeybee
-
-
1998
Blue orchard bee
14,875
5.44
1999
Blue orchard bee
4,150*
2.17
2000
Blue orchard bee
16,935
4.21
2001
Blue orchard bee
4,415**
1.03
2002
Blue orchard bee
-*
2.45
2003
Blue orchard bee
6,680***
0.62
* Freezing event; ** missed timing on BOB release; ***high bee predation by birds
Number of females
Optimal number of nesting females for adequate pollination
Blue orchard bee
Almond
Apple
# nesting females/acre
300
250
3
2.5
# females/tree
In comparison, need 1 - 2.5
honeybee hives / acre
(typically 30,000 - 50,000
workers / hive)
Pollination efficiency
Flower efficiency and fidelity
• 75 flowers per “load” of pollen and nectar
• 15-35 loads per provision
Christelle Guédot, UW-Madison
• 75 X 25 (avg.) = 1,875 flower visits per provision
• Female provisions 7 – 12 cells in her life
• A single female visits 10,000-20,000 flowers in her lifetime!
• Remember: 85-100% orchard flower pollen
How to manage the blue orchard bee
What do you need to have
blue orchard bees
in your orchard?
• Care, attention, enthusiasm
• Bee stock
• Nesting equipment
• Appropriate storage facility
• Proper handling
http://www.sare.org/LearningCenter/Books/How-to-Manage-the-BlueOrchard-Bee
Where to obtain bees and materials
Nesting shelters
• Attach shelter on tree or fence post
• Orient SE for longer foraging
activity (and more attractive to
nesting females)
James Cane, USDA ARS
Shelter with wooden blocks
and chicken wire
Nesting blocks
Prefer wood blocks
Paper straws in cavities help for handling
and storage
Reeds
Wafer boards
Nesting cavities
- 19/64” (7.5 mm) hole diameter
- 6” (15 cm) long
- Plan on 3-5 nesting cavities per female released
Nesting material
• Mud is a vital nesting material
• Clayey mud, not sand or loam
• Need safe place for gathering mud, within 20-50ft. of nest
A typical BOB season
Example for Northern Utah
1) March/April
About two weeks prior to expected bloom:
• Check flower development
• Check weather forecast
A typical BOB season
2) March/April
•
•
•
Set up nesting materials and mud sources
Incubate bees at 72-76°F (22-25°C)
Emerged bees can be held at 37-41ºF for ~a week
A typical BOB season
3) March/April
Release BOB population (200-300 females + 400-600 males per
acre for full pollination in almonds, cherries, apples, and pears)
A typical BOB season
4) May/June
Retrieve nesting materials
• Move nests to summer storage (avoid excessive heat, direct sun)
• Take measures to avoid parasitism
Adult female chalcid
wasp, Monodontomerus
Blue orchard bee nests by black light trap
Note large numbers of drowned
Monodontomerus in tray
Adult female chalcid wasp,
Melittobia chalybii
A typical BOB season
5) June through August
Monitor development with monthly development checks
• Select 10 male cocoons from different nests
A typical BOB season
6) Mid/late September
Move nests to winter storage (refrigerator)
• Check small sample of females from different nests to be sure
that all adults
• Best if population held for 1 week at 55°F before being placed
in artificial wintering at 39°F
• Require minimum of 3 months wintering: adults go dormant
(diapause)
A typical BOB season
7) November/December
•
•
•
Quantify population
Remove parasites and diseased bees (now dead)
Prepare nesting materials for the following season
Hairy-fingered pollen mite,
Chaetodactylus krombeini
Chalkbrood fungus
Recently emerged male covered with
migratory nymphs of hairy-fingered mite
Summary
• Blue orchard bees
are superb orchard
pollinators
• BOBs can be used
alone or along with
honey bees
• Easy management
• Bees are safe
Spray guide
Acknowledgements
• Jordi Bosch
• Theresa Pitts-Singer
• William P. Kemp
• USDA-ARS Beelab

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