San Joaquin Valley

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San Joaquin Valley Table Grape Seminar Using
Black Widow Spider Biology to Improve
Control Kent Daane, Glenn Yokota, Pedro
Hernandez California Table Grape Commission
University of California
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Why is there a concern?
1. Public fear
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Why is there a concern?
3. BWS is an Invasive
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Outline How to sample BWS where are they in the
vineyard what is their seasonal
development sampling program How to kill
BWS which pesticides work best when to treat
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Where are BWS in the vineyard?
Sampled 2003-05 4-5 vineyard blocks collected
every 2-4 weeks BWS number, age, sex BWS location
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Where are BWS in the vineyard?
Spiders () per vine section
Berm
Base- trunk
Mid- trunk
Cordon
Arms
Canopy
Cluster
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5 - On ground w/o apparent vine support
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40-60 - Base of trunk/trellis (look for webs)
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Peeling bark old leaves often form nest
structure
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20-25 - Mid-trunk - between stake and trunk
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In vine crevices (no trellis / ground support)
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Where are BWS in the vineyard?
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Where are BWS in the vineyard Hiding
In Stake (4)
Upper Cordon (15-20)
Leaves (2)
Arms (5)
Canopy (1)
Mid-Trunk (15-25)
Base-Trunk (40-60)
Berm, leaf-litter (5)
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Black widow spider vineyard
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Where are BWS in the vineyard?
Metal stake- 4 inch
Metal stake- 1 inch
Black widow spider vineyards Wood stakes
far/close C-Metal stakes far/close T-Metal
stakes far/close Milk cartons for
replants Cement valves/leaves
Wood stake- 4 inch
Wood stake- 1 inch
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Where are BWS in the vineyard?
Overhead trellis Standard T-trellis
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Spiders per vine (sum SEM)
4
2
0
Aug
Sept
Oct
Nov
Dec
Jan 07
Feb
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Where are BWS in the vineyard?
0.6
Habitat preferences
0.5
0.4
Spiders per vine SEM)
0.3
0.2
0.1
0.0
Leaves
No stake
Wood 1-in
Milk carton
Metal T 4-in
Metal T 1-in
Metal C 1-in
Metal C 4-in
Cement Valve
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Recognizing black widows busting myths
Female BWS Egg sac
Egg sac Spiderlings
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Recognizing black widows busting myths
BWS spiderling (1/64th inch)
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Recognizing black widows busting myths
BWS adult male
immature female (3/4 inch)
Nearly mature females have beautiful color
pattern on top!
(top)
(bottom)
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(No Transcript)
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How does the BWS age structure change?
April-October egg sac
Spring Summer 2-3 generations
Winter / Fall
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How does the BWS age structure change?
100
Egg Sac Spiderling Immature Adult Empty Nest
90
80
70
60
50
Black widow spiders per 200 vines
40
30
20
10
0
Jul/20/04
Oct/23/03
Jan/22/04
Apr/21/04
Jun/21/04
Oct/22/04
Jan/19/05
Apr/22/05
Aug/21/03
Sep/19/03
Nov/21/03
Dec/22/03
Feb/20/04
Mar/22/04
Aug/19/04
Sep/22/04
Nov/22/04
Dec/17/04
Feb/23/05
Mar/24/05
May/20/04
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How does the BWS age structure change?
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Egg Sac Spiderling Immature Adult Empty Nest
30
25
20
Black widow spiders per 200 vines
15
10
5
0
Oct/6/04
Apr/6/05
Mar/8/05
Feb/9/05
Sep/8/04
Dec/6/04
Oct/10/03
Apr/13/04
Jul/15/04
Jan/13/04
Mar/12/04
May/11/04
Jan/12/05
Nov/10/03
Feb/13/04
Aug/10/04
Nov/10/04
Sep/12/03
Dec/12/03
Jun /11/04
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How does the BWS age structure change?
90
Egg Sac Spiderling Immature Adult Empty Nest
80
70
60
50
Black widow spiders per 200 vines
40
30
20
10
0
Oct/31/03
Oct/29/04
Apr/26/05
Mar/29/04
Apr/29/04
Jul/27/04
Mar/29/05
Aug/27/03
Nov/26/03
May/27/04
Jun/29/04
Aug/27/04
Nov/29/04
Jan/31/05
Feb/27/04
Feb/28/05
Sep/26/03
Dec/26/03
Sep/29/04
Dec/29/04
Jan /27/04
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Population increase from a point source
255.8 ? 22.5 spiderling / egg
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Population increase from a point source
start
finish
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24 hr sampling
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2.0
September
1.5
1.0
0.5
0.0
Black widow exposure rating 0 hidden, 2
exposed
2.0
January
1.5
1.0
0.5
0.0
7am
5pm
7pm
9pm
11pm
1am
3am
5am
1pm
3pm
7am
9am
11am
Midnight
Noon
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How to sample BWS Look in hot spots Record
webs on 1000 vines / block (fast, walk 5-10
rows) Mark 50-100 vines with webs (visit webs
after dark) Destroy webs before
pesticides (visit 3-7 days post spray)
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Outline How to sample BWS where are they in the
vineyard what is their seasonal
development sampling program How to kill
BWS which pesticides work best when to treat
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Contact sprays for adult BWS
Lorsban, Lannate Applaud, Omite,
Abermectin Provado Danitol
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Contact sprays for adult BWS
Applaud, Provado
100
Agrimek (10)
Omite (25)
Survival ()
50
Danitol, Lannate, Lorsban (100)
0
0
1
2
3
5
7
10
Days after application
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Residual activity on bark for adult BWS

Control Lannate
Danitol
Lorsban
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(No Transcript)
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Sowhich insecticides are best for BWS?
Dead adult BWS
Live immatures
Delayed dormant Lorsban
Lorsban kills adult BWS, but had little impact on
immatures
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Summary, Conclusions and Questions.
Recognize BWS stages.. Look for webs in popular
hiding spots
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Summary, Conclusions and Questions.
Consider spot treatments Delayed-dormant
Lorsban kills adults, not immatures In-season
Danitol In-season Lannate
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Summary, Conclusions and Questions.
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Summary, Conclusions and Questions.
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(No Transcript)
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Spiderlings main predator other spiders!
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Label rate of Danitol, Lorsban Lannate

100
99.9
LD
9.1 of label rate
99
99
90
70
LD
2.5 of label rate
Mortality ()
50
50
Lannate for adult females
30
10
1
0.1
0.01
0.1
10
100
1
Dose insecticide application (as label rate)