POLLINATORS AND
CLIMATE CHANGE
photo by
Steve
Dupey
James H. Cane, USDA Agricultural Research
Service, Utah State University, Logan, Utah
Predictions for Great Basin
 Region-wide
warming, 4-9° F
 Earlier springs, longer summers
 Precipitation – more? less? snowpack?
 CO2 increase and
invasive C3 grasses
(cheatgrass)
 Earlier, longer
fire seasons
Chambers, J. C. Climate change and the Great Basin. RMRS-GTR204, 29-32. 2008. USDA Forest Service Gen. Tech. Rep.
POLLINATORS AND GLOBAL
WARMING
 Voltinism
and seasonality
 Geographically variable thermal adaptation
 Migration potential
 Lethal heat thresholds - Climate and fire
photo by Steve Dupey
CUES OF SEASONALITY
 Generation
cues - voltinism
 Developmental transition cues
 Day-length versus thermal cues
 Synchronization with host bloom
ANNUAL LIFE CYCLE OF A
UNIVOLTINE BEE
Egg
stage- 3-6 days
ANNUAL LIFE CYCLE OF A
UNIVOLTINE BEE
Larval
feeding stage-3-5 weeks
ANNUAL LIFE CYCLE OF A
UNIVOLTINE BEE
Prepupa
-resting
stage- 10 months
ANNUAL LIFE CYCLE OF A
UNIVOLTINE BEE
Transformation
pupa- 1-2 weeks
stage-
ANNUAL LIFE CYCLE OF A
UNIVOLTINE BEE
Adult
stage- 2-3 weeks
Daylength cues
perceptible to immatures
within the nest before
emergence as adults
VOLTINISM
Bees have 4 discrete life stages
 Our bees have fixed overwintering stages




Prepupa
Adult – early spring option
Voltinism- generations per year




Fixed univoltine
Bivoltine
Multivoltine
Social species
WA
UT
FARM NEWS
Warming Climate Threatens California Fruit And Nut Production
Davis CA (SPX) Jul 22, 2009
“Winter chill, a vital climatic trigger for many tree crops, is
likely to decrease by more than 50 percent during this
century as global climate warms, making California no
longer suitable for growing many fruit and nut crops,
according to a team of researchers from the University of
California, Davis, and the University of Washington.
In some parts of California's agriculturally rich Central
Valley, winter chill has already declined by nearly 30
percent, the researchers found.”
MIGRATION POTENTIAL
 historical
evidence for geographic range shifts
 Nesting habits of non-natives


Cavity-nesters as hitchhikers
Ground-nesters- prevalent, few cases
Andrena wilkella
Lasioglossum leucozonium
Lethal heat thresholds
- Climate
and fire
100
80
60
1 min
3 min
9 min
27 min
Du
ra
tio
20
Temp
eratu
r
54
°C
°C
50
°C
46
42
°C
0
°C
n
40
38
l (%)
Larval Surviva
Survival of Megachile rotundata larvae following
heating in damp sand
e
Summer soil temp profiles- Arizona
desert scrub (mesquite)
2.5- 5 cm depth
5-10 cm depth
32 hr > 45 C
46 C
20 hr > 41 C
43 C
Subtropical mesquite-dominated grassland in southern AZ
June, July, August 2006
Concluding thoughts

Lesser worries for bees




Primary concern- degradation of Great Basin
plant communities. Forb losses  Bee losses





direct heat effects on life stages
bees following migrating plants
bees losing synchrony with bloom
invasive weed monocultures (e.g. Old World grasses)
detrimental fire cycles
intensified, prolonged, more frequent drought
poor grazing practices – too many, too soon, too long
Adaptive proactive management