Anticipating Success
Predicting Dates for Important
Hive Events
Keith Tignor
Virginia Department of Agriculture and
Consumer Services
Winter Adaptation
•
•
•
•
•
•
Cavity Dweller
Food Storage
Brood Suspension
Life Span Extension
Expandable Rectum
Clustering Behavior
Temperature Threshold and Growth
Rate Potential
Temperature Regulation
• Insect management
• Crop planting and harvest
• Designing orchards (and flower beds) for
sequential bloom or fruit maturity
• Planning refuge plantings for beneficial
insects
• Tracking global warming trends
• Predicting bloom dates (honey flow)
Winter Honey Bee Cluster and Hive
Temperatures with Brood Present
100
90
Center
Temperature (F)
80
70
Edge
60
50
40
30
Ambient
20
10
Date
Average Cluster Temperature: 93.1 + 0.02 F
Average Edge Temperature: 52.4 + 0.36 F
Average Ambient Temperature: 34.4 + 0.32 F
Predicting Bloom Dates
• Day length and other environmental factors
can affect specific events in a plants life
cycle
• Different cultivars frequently have different
bloom periods
• Bloom Prediction Models include:
– Calendar Date
– Day length
– Last frost date
– Growing Degree Days (GDD)
Predicting Bloom Dates
• Plant growth responds to accumulating heat
units to some degree.
• Bud swell, leaf emergence, flowering,
fruiting, and other growth stages can be
correlated to the cumulative daily
temperature.
• Bloom dates correlates more precise when
using Growing Degree Days (GDD).
Growing Degree Days
• Calculated from Average of daily maximum,
Tmax, and minimum, Tmin, temperatures
compared to a base temperature, Tbase.
• GDD= ((Tmax + Tmin)/2) - Tbase.
• Tbase temperatures of 50°F or 60°F.
• Mean daily temperature lower than the base
temperature GDD=0.
• Maximum temperature capped at 86°F.
• Minimum temperature limited to Tbase.
Growing Degree Days
• High = 80 °F
• Low = 60 °F
• GDD = 80 plus 60 divided by 2 (70) minus 50 = 20
• High = 48 °F
• Low = 28 °F
• GDD = 50 plus 50 divided by 2 (50) minus 50 = 0
• High = 60 °F
• Low = 45 °F
• GDD = 60 plus 50 divided by 2 (55) minus 50 = 5
• High = 90 °F
• Low = 70 °F
• GDD = 86 plus 70 divided by 2 (78) minus 50 = 28
Growing Degree Days in Colonial Heights, VA
Cumulative Growing Degree Day (no.)
5000
4500
50 F
4000
3500
3000
2500
60 F
2000
1500
1000
500
0
Jan
Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Date (Month)
Growing Degree Days1 in Colonial Heights, VA
1000
Growing Degree Day (no.)
900
800
700
600
500
400
300
200
100
0
Jan
Feb Mar Apr May Jun
Jul
Date (Month)
1Accumulated
value for the average daily temperature
minus a base or minimum temperature of 50°F.
Aug Sep Oct Nov Dec
Growing Degree Days1 in Colonial Heights, VA
Cumulative Growing Degree Day (no.)
3000
2010
2011
2012
2013
2014
2500
2000
1500
1000
500
0
Jan
1Accumulated
Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Date (Month)
value for the average daily temperature
minus a base or minimum temperature of 60°F.
2014 Growing Degree Days1 in Virginia Regions
3000
Growing Degree Day
2500
2000
Heathsville
Colonial Heights
Charlottesville
Highland
Abingdon
1500
1000
500
0
Jan
1Accumulated
Feb
Mar
value for the average daily temperature
minus a base or minimum temperature of 50°F.
Apr
May Jun Jul
Date (Month)
Aug
Sep
Oct
Nov
Growing Degree Day Information
• University of Virginia Climatology Office:
climate.virginia.edu/online_data.htm
• The Weather Channel:
www.yourweekendview.com/outdoors/agriculture/growing-degree-days
• Dupont Pioneer:
www.pioneer.com/home/site/ca/agronomy/tools/gdu
• USA National Phenology Network: www.usanpn.org
• Weather Underground : www.wunderground.com/history/airport/
• Farm Progress: Mobile App (iTunes, Google Play)
• Ag PhD GDU Calculator: Mobile App (iTunes, Google Play)
GDD Mobile Apps
Airport Weather Information
City served
FAA
ICAO
Airport name
Wise
LNP
KLNP
Lonesome Pine Airport
Winchester
OKV
KOKV
Winchester Regional Airport
Williamsburg
JGG
KJGG
Williamsburg-Jamestown Airport
West Point
FYJ
KFYJ
Middle Peninsula Regional Airport
Washington, D.C. / Manassas
HEF
KHEF
Manassas Regional Airport (Harry P. Davis
Field)
Washington, D.C. / Chantilly /
Dulles
IAD
KIAD
Washington Dulles International Airport
Washington, D.C. / Arlington
County
DCA
KDCA
Ronald Reagan Washington National
Airport
Warrenton
HWY
KHWY
Warrenton-Fauquier Airport
Wallops Island
WAL
KWAL
Wallops Flight Facility (NASA)
Virginia Beach
NTU
KNTU
NAS Oceana (Apollo Soucek Field)
Weather Underground
Growing Degree Days
in Colonial Heights, VA, on April 22nd
Cumulative Growing Degree Day (no.)
900
800
Farm Progress
700
600
500
400
Weather.com
300
200
100
0
2010
1Accumulated
2011
value for the average daily temperature
minus a base or minimum temperature of 50°F.
2012
2013
Date (Year)
2014
2015
Growing Degree Days1 in Colonial Heights, VA
Cumulative Growing Degree Day (no.)
700
600
March 25
April 22
500
400
Locust Bloom
352.7
300
200
100
0
2008
1Accumulated
2009
value for the average daily temperature minus
a minimum base temperature of 50°F from Weather.com.
2010
2011
Date (Year)
2012
2013
Key Phenological Events
to Track
First bloom: date first flower
on the plant opens to reveal
pistils and/or stamens.
Full bloom: date 95% of
flowers have opened (e.g. 1
out of 20 buds remains
closed).
Honey Bee Annual Colony
Population in Virginia
60000
Adult
50000
Brood
40000
30000
20000
10000
0
Jan
Feb Mar Apr May Jun
Jul
Aug Sept Oct Nov Dec
Winter Honey Bee Cluster and Hive
Temperatures with Brood Present
100
90
Center
Temperature (F)
80
70
Edge
60
50
40
30
Ambient
20
10
Date
Average Cluster Temperature: 93.1 + 0.02 F
Average Edge Temperature: 52.4 + 0.36 F
Average Ambient Temperature: 34.4 + 0.32 F
Passive Heat Retention in Bee Hives
Temperature Variation and Retention
in Insulated Hives
8
Paper
Temperature Variation (°F)
6
Foam
4
Tunnel
2
Uninsulated
0
-2
-4
-6
-8
7
5
3
Glen Allen, VA, January 2016; sunrise ~ 07:19; sunset ~ 17:25
1
23
21
19
17
15
13
11
9
7
Time
Internal Temperatures in Wrapped Hives
50
Paper
Hive Temperature (°F)
45
40
35
Foam
Ambient
30
25
20
7
5
3
1
Glen Allen, VA, January 2016; sunrise ~ 07:19; sunset ~ 17:25
23
21
19
17
15
13
11
9
7
Time (hr.)