Asian Citrus Psyllid and Huanglongbing
Neil McRoberts & Carrie Teiken, UC Davis Beth Grafton-Cardwell, UC Riverside
Tim Gottwald & Weiqi Luo, USDA-ARS Ft Pierce, FL Paul Mitchell, UW Madison, WI
Len Coop, OSU, Corvallis, OR
Overview
• Introduction to pest and pathogen
• Indication of California situation
• Industry, State and federal responses to HLB threat
Asian Citrus Psyllid (Diaphorina citri) and
HLB (Candidatus Liberibacter asiaticus) http://californiacitrusthreat.org/
ACP/HLB situation in California
• ACP first discovered in 2008
• Now widespread in much of southern California
• In 2013 ACP detections in southern San Joaquin Valley became more frequent
• To date only 1 confirmed case of HLB: tree in residential neighborhood of greater LA.
http://www.cdfa.ca.gov/plant/acp/index.html
Incursion of ACP into the San Joaquin Valley
CA 99
CA 65
CA 198
Source: CDFA CA ACP Quarantine areas; web interface
ACP detections in 2013
Tim Gottwald
Weiqi Luo
Neil McRoberts
IRCHLB III: Risk-based Residential HLB/ACP Survey for California,
Texas, and Arizona
Purpose of a CA Residential Survey
• Justification: • Early detection of HLB to:
• Maximize regulatory intervention and disease control.
• Minimize disease incidence, spread, and impact to commercial
citrus industry.
• The recent finds of HLB underscore the urgency
• Los Angeles basin (residential)
• Texas (Commercial planting)
• Requisites and Goals:
• A statistically accurate and justifiable survey protocol to be
used pre- and post-discovery - for early detection across all
citrus industries within the US that: • Incorporates all HLB/ACP biological and epidemiological factors.
• Can be applied across residential areas and commercial citrus.
• Has high probability for early detection of both HLB and ACP.
• Maximizes targeting of control/mitigation efforts.
• Maximizes fiscal and manpower resources.
Model framework
Elevation
Water Land cover
Military
Indian Reservation
Filtering Original Census tract
Resulting residential area
Population
& race
ACP+
Risk modeling
Final risk
mapping
and
survey
protocol
ACP-
(Nursery & Big box store
Citrus green waste)
Weather
Inte
gra
tio
n
Citrus transport
2. Risk Modeling Determining risk variables and their effects
Formula & algorithm Estimate total risk in residential area, including:
1. Residential citrus population and distribution
2. Residential Asian population risk
3. ACP+ location risk
4. Citrus production related transport corridors
5. Potential ACP spread risk from commercial
nursery , green waste facility, military
installation, packing house and flea market
6. Distance to Mexico-TX border crossing
7. HLB and ACP -- LAS+ locations risk
8. Proximity to commercial citrus groves
(adjustment for sampling intensity)
Residential citrus:
Residential Asian risk:
ACP+ risk:
Transportation risk:
Potential ACP risk:
LAS+ risk
Border crossing risk:
Output variables
citrusPop
AsianR
ACPR
ACPR
BorderR
Total risk= Residential citrus *{([Asian] + [ACP+] + [Road]+ [ACP-]+[Border])/5+[LAS+]}
=
LAS
BorderACPRoadACPAsiancitrus R
RRRRRPop
5
)(*)log(
Total risk Sampling intensity Proximity to commercial citrus groves
RoadR
No prior preference for each risk factor, so
equal weight is applied.
The suitable weighting to be determined later
from survey results.
LASR
Potential
HLB risk
Known
HLB risk
Formula & algorithm
Full information available: Gottwald & Luo, An investigation of transport network on HLB/ACP spread.
4. Estimate risk from citrus fruit transport corridor (to packinghouse and juice plants)
• Apply HLB/ACP spread curve determined from Florida data
Major
routes with
strong
effects on
HLB
Major
routes with
strong
effects on
ACP
Distance to commercial citrus groves
Not ‘Risk’ but affects sampling intensity Proposed new sampling scheme
Linked with ACP dispersal
curve determined from FL data
Southern California Rio Grande Valley, TX
3. Risk Mapping Integrating filtering and risk variables with GIS data to
develop survey design and intensity
Rio Grande Valley, TX
Southern California
Total risk map (Considers all
variables and filtering)
Incursion of ACP into the San Joaquin Valley
CA 99
CA 65
CA 198
Source: CDFA CA ACP Quarantine areas; web interface
ACP detections in 2013
Manpower and number of survey
cycles/year
1 cycle/year
2 cycles/year
1 cycle/year
2 cycles/year
2 cycles/yr does not
detect disease at as low
an incidence
Risk-based sampling (1or 2 cycles/year)
Extra assurance = Includes random
selection of a small proportion of low risk
STR areas.
In case we are totally wrong!!!!
1 cycle/year
2830 STR grids selected based on risk
2 cycles/year Cycle 1: 1393 STR grids
2 cycles/year
Cycle 2: 1464 STR grids
For more information on risk
assessment
http://www.plantmanagementnetwork.org/edcenter/seminars/outreach/Citrus/HLB/
A webcast by Dr Gottwald describing the process of building and deploying the
risk model, mapping, and survey protocols is available at:
Medium to long-term solutions
• Organize growers into neighborhood (area-
wide) response groups (learn from unfortunate
FL experience).
• Breed and release an altered Psyllid which is
not competent as a vector for Clas.
– Subject of $15M USDA/Industry CAP grant
Where would Psyllid sit in the spectrum of opinion about GM traits?
Division of Google ranked pages on page 1 of searches for “GM corn”, “GM papaya” and “GM mosquito”.
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
For Neutral Against
Corn
Papaya
Mosquito
Genetic pollution
Unnatural technology
Agricultural sustainability
Editorializing
Genetic pollution
Corporate greed/monopolies
Unnatural technology
Scientific merits
Ecological risk
Technology dread
Human health benefit
Crossing the Rubicon
Adopting a biotech solution moves the industry to a qualitatively different place in public perception
Does it have to?
Simple causal model: a first look at Psyllid deployment
Industry see
ACP as useful
Use of ACP
Decrease insecticide
use Industry backs
ACP
ACP developed Political
support for ACP
Public thinks ACP is
dangerous
Public thinks ACP is
harmful
Demonstrating benefit and avoiding antagonism could lead to sustainable Psyllid use
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30
Growers perceive nu_ACP as
beneficial 1 -1 5 3 11 16 55 81 208 404 923
182
1
404
3
835
0
###
#
###
#
###
#
###
#
###
#
###
#
2E+
06
###
#
###
#
###
#
###
#
###
#
###
#
###
#
###
#
###
#
###
#
Adoption of nuPsyllid 0 1 -1 5 3 11 16 55 81 208 404 923
182
1
404
3
835
0
###
#
###
#
###
#
###
#
###
#
8E+
05
###
#
###
#
###
#
###
#
###
#
###
#
###
#
###
#
###
#
###
#
Decrease in pesticide use 1 0 1 -1 5 3 11 16 55 81 208 404 923
182
1
404
3
835
0
###
#
###
#
###
#
###
#
4E+
05
###
#
###
#
###
#
###
#
###
#
###
#
###
#
###
#
###
#
###
#
Industry promotes nu_ACP
technology 0 5 2 10 11 42 54 154 279 662
127
1
288
1
586
1
###
#
###
#
###
#
###
#
###
#
###
#
###
#
2E+
06
###
#
###
#
###
#
###
#
###
#
###
#
###
#
###
#
###
#
###
#
Nu_ACP developed 1 2 5 6 23 34 88 165 388 758
168
8
347
1
750
2
###
#
###
#
###
#
###
#
###
#
###
#
###
#
3E+
06
###
#
###
#
###
#
###
#
###
#
###
#
###
#
###
#
###
#
###
#
Political support for nu_ACP
technology 1 0 0 5 9 19 40 98 190 414 873
187
7
390
6
835
3
###
#
###
#
###
#
###
#
###
#
###
#
2E+
06
###
#
###
#
###
#
###
#
###
#
###
#
###
#
###
#
###
#
###
#
Public perceives nu_ACP as
dangerous 1 0 0 -1 0 -5 -8 -19 -35 -90 -171 -379 -783
-
170
6
-
352
7
-
757
0
###
#
###
#
###
#
###
#
####
#
###
#
###
#
###
#
###
#
###
#
###
#
###
#
###
#
###
#
###
#
Public perceives nu_ACP crops
as harmful 1 0 0 -1 0 -5 -8 -19 -35 -90 -171 -379 -783
-
170
6
-
352
7
-
757
0
###
#
###
#
###
#
###
#
####
#
###
#
###
#
###
#
###
#
###
#
###
#
###
#
###
#
###
#
###
#
Growers perceive nu_ACP as
beneficial -1 5 3 11 16 55 81 208 404 923
182
1
404
3
835
0
###
#
###
#
###
#
###
#
###
#
###
#
2E+
06
###
#
###
#
###
#
###
#
###
#
###
#
###
#
###
#
###
#
###
#
Adoption of nuPsyllid 1 -1 5 3 11 16 55 81 208 404 923
182
1
404
3
835
0
###
#
###
#
###
#
###
#
###
#
8E+
05
###
#
###
#
###
#
###
#
###
#
###
#
###
#
###
#
###
#
###
#
Decrease in pesticide use 0 1 -1 5 3 11 16 55 81 208 404 923
182
1
404
3
835
0
###
#
###
#
###
#
###
#
4E+
05
###
#
###
#
###
#
###
#
###
#
###
#
###
#
###
#
###
#
###
#
Industry promotes GM technology 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
Industry develops GM technology 2 5 6 23 34 88 165 388 758
168
8
347
1
750
2
###
#
###
#
###
#
###
#
###
#
###
#
###
#
3E+
06
###
#
###
#
###
#
###
#
###
#
###
#
###
#
###
#
###
#
###
#
Political support for GM
technology 0 0 5 9 19 40 98 190 414 873
187
7
390
6
835
3
###
#
###
#
###
#
###
#
###
#
###
#
2E+
06
###
#
###
#
###
#
###
#
###
#
###
#
###
#
###
#
###
#
###
#
Public perceives GM technology
as dangerous 0 0 -1 0 -5 -8 -19 -35 -90 -171 -379 -783
-
170
6
-
352
7
-
757
0
###
#
###
#
###
#
###
#
####
#
###
#
###
#
###
#
###
#
###
#
###
#
###
#
###
#
###
#
###
#
Public perceives GM crops as
harmful 0 0 -1 0 -5 -8 -19 -35 -90 -171 -379 -783
-
170
6
-
352
7
-
757
0
###
#
###
#
###
#
###
#
####
#
###
#
###
#
###
#
###
#
###
#
###
#
###
#
###
#
###
#
###
#
It may even be possible at low direct cost to the industry
What happens if public opinion is strengthened by industry promotion?
Industry see
ACP as useful
Use of ACP
Decrease insecticide
use Industry backs
ACP
ACP developed Political
support for ACP
Public thinks ACP is
dangerous
Public thinks ACP is
harmful
With feedback between industry PR and public opinion things get messy
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30
Growers perceive nu_ACP as
beneficial 1 -1 5 -7 7 -34 -9 -185 -140 -800 -725
-
281
9
-
196
1
-
694
6
156
4
-
129
8
###
#
###
#
###
#
###
#
2E+
06
###
#
###
#
###
#
###
#
###
#
###
#
###
#
###
#
###
#
###
#
Adoption of nuPsyllid 0 1 -1 5 -7 7 -34 -9 -185 -140 -800 -725
-
281
9
-
196
1
-
694
6
156
4
-
129
8
###
#
###
#
###
#
8E+
05
###
#
###
#
###
#
###
#
###
#
###
#
###
#
###
#
###
#
###
#
Decrease in pesticide use 1 0 1 -1 5 -7 7 -34 -9 -185 -140 -800 -725
-
281
9
-
196
1
-
694
6
156
4
-
129
8
###
#
###
#
4E+
05
###
#
###
#
###
#
###
#
###
#
###
#
###
#
###
#
###
#
###
#
Industry promotes nu_ACP
technology 0 5 2 20 15 72 40 192 -41 146
-
133
1
-
219
5
###
#
###
#
###
#
###
#
###
#
###
#
###
#
###
#
####
#
###
#
###
#
###
#
###
#
###
#
###
#
###
#
###
#
###
#
###
#
Nu_ACP developed 1 2 5 6 13 0 -4 -111 -270 -892
-
187
8
-
466
7
-
875
2
###
#
###
#
###
#
###
#
-
385
7
###
#
###
#
3E+
06
###
#
###
#
###
#
###
#
###
#
###
#
###
#
###
#
###
#
###
#
Political support for nu_ACP
technology 1 0 0 -5 -15 -49 -108 -268 -526
-
108
4
-
181
1
-
301
3
-
331
0
-
168
1
###
#
###
#
###
#
###
#
###
#
###
#
4E+
06
###
#
###
#
###
#
###
#
###
#
###
#
###
#
###
#
###
#
###
#
Public perceives nu_ACP as
dangerous 1 0 5 6 27 37 116 149 375 343 674 -517
-
191
2
###
#
###
#
###
#
###
#
###
#
###
#
###
#
####
#
###
#
###
#
###
#
###
#
###
#
###
#
###
#
###
#
###
#
###
#
Public perceives nu_ACP crops as
harmful 1 0 5 6 27 37 116 149 375 343 674 -517
-
191
2
###
#
###
#
###
#
###
#
###
#
###
#
###
#
####
#
###
#
###
#
###
#
###
#
###
#
###
#
###
#
###
#
###
#
###
#
What happens if public opinion is strengthened by industry promotion?
Industry see
ACP as useful
Use of ACP
Decrease insecticide
use Industry backs
ACP
ACP developed Political
support for ACP
Public thinks ACP is
dangerous
Public thinks ACP is
harmful
With negative feedback between industry PR and skeptical public opinion there is hope
Growers perceive nu_ACP as
beneficial -1 3 3.1 7.08 12.3 33.6 54.6 129 252 533
107
4
225
6
458
6
952
3
###
#
###
#
###
#
###
#
###
#
7E+
05
###
#
###
#
###
#
###
#
###
#
###
#
###
#
###
#
###
#
###
#
Adoption of nuPsyllid 1 -1 3 3.1 7.08 12.3 33.6 54.6 129 252 533
107
4
225
6
458
6
952
3
###
#
###
#
###
#
###
#
4E+
05
###
#
###
#
###
#
###
#
###
#
###
#
###
#
###
#
###
#
###
#
Decrease in pesticide use 0 1 -1 3 3.1 7.08 12.3 33.6 54.6 129 252 533
107
4
225
6
458
6
952
3
###
#
###
#
###
#
2E+
05
###
#
###
#
###
#
###
#
###
#
###
#
###
#
###
#
###
#
###
#
Industry promotes GM technology 5 4 9.9 10.9 31.9 48.3 117 216 472 928
197
0
397
9
829
5
###
#
###
#
###
#
###
#
###
#
###
#
1E+
06
###
#
###
#
###
#
###
#
###
#
###
#
###
#
###
#
###
#
###
#
Industry develops GM technology 2 5 4 17.1 24.4 62.8 115 257 500
107
2
215
5
450
7
920
2
###
#
###
#
###
#
###
#
###
#
###
#
1E+
06
###
#
###
#
###
#
###
#
###
#
###
#
###
#
###
#
###
#
###
#
Political support for GM technology 0 -2 1.1 3.28 11.6 21.1 52.2 101 220 442 930
189
3
393
7
807
0
###
#
###
#
###
#
###
#
###
#
6E+
05
###
#
###
#
###
#
###
#
###
#
###
#
###
#
###
#
###
#
###
#
Public perceives GM technology as
dangerous 1 0.95 0.91 0.81 0.7 0.38 -0.1
-
1.27
-
3.42
-
8.14
-
17.4
-
37.1
-
76.9 -160 -329 -681
-
140
2
-
289
1
-
595
6
####
#
###
#
###
#
###
#
###
#
###
#
###
#
###
#
###
#
###
#
###
#
Public perceives GM crops as
harmful 1 0.95 0.91 0.81 0.7 0.38 -0.1
-
1.27
-
3.42
-
8.14
-
17.4
-
37.1
-
76.9 -160 -329 -681
-
140
2
-
289
1
-
595
6
####
#
###
#
###
#
###
#
###
#
###
#
###
#
###
#
###
#
###
#
###
#
Acknowledgements
• USDA
• Citrus Research & Development Foundation (FL)
• Citrus Research Board (CA)
