Presentation at the RTB Annual Review and Planning Meeting (Entebbe, Uganda, 29 Sep-3 Oct 2014)

1. A region-wide response to
emerging cassava pests
and diseases in SE Asia
Kris A.G. Wyckhuys
RTB Annual Review & Planning
Meeting
30/09/2014

2. Outline
 Antecedents
 SE Asian cassava
 Plant health situation
 Invasive pests & emerging diseases
 Cassava mealybug complex
 Cassava witches broom
 Ongoing initiatives
 Monitoring
 Capacity building
 Applied research
 Extension
 Partnerships: cornerstone of success

3. Cassava in SE Asia
8,000,000 40,000,000
X 4
Smallholder producers
Thailand Indonesia
2-3 ha/farm 0.2-0.5 ha/farm
Cambodia Laos
1-4 ha/farm 0.3-0.4 ha/farm

4. Cassava in SE Asia

5. Cassava in SE Asia

6. Invasive pests widen yield gap
Paracoccus marginatus
Phenacoccus manihoti
Cassava mealybug
Papaya mealybug
First record: 2008 – Indonesia
2010 – Cambodia, Thailand
First record: 2009
Eastern seaboard Thailand
Host range: 80 host plant spp.
Cassava, papaya, sweetpotato
Host range: 9 host plant spp.
Cassava, soybean, citrus
Cassava yield impact: 40% loss
Yield impact: up to 84% loss
Initial impact: 20-40% loss (2010,
Thailand)
(2013, India)
Ferrisia virgata
Striped mealybug
Pseudococcus jackbeardsleyi
Jackbeardsleyi mealybug
First record: 1942 – Thailand
First record: 1987 – Thailand
Host range: 272 plant spp.
Cassava, coffee, guava, cashew,
Host range: 131 plant spp.
Cassava, citrus
guava, mango, cacao
Cassava yield impact: 20-80%
Cassava yield impact: unknown
(Bellotti et al., 2013)

7. P. manihoti impact forecasts
Hyman & Herrera, unpublished

8. P. manihoti direct economic impact
Country Total area
affected (ha)
Average
2010 yield
(t/ha)
Country-level yield loss
estimates (1000 t)
Worst case
(84%)
Intermediate
(30%)
Thailand 246,167 18.8 3,794 1,388
Indonesia 145,556 20.2 2,411 882
India 43,600 34.8 1,244 455
Vietnam 39,503 17.3 560 205
China 4,998 16.8 69 25
Cambodia 2,843 21.0 49 18
Lao PDR 1,322 25.1 27 9
Burma 1,321 13.5 15 5

9. CWB: an emerging curse on cassava
 Cassava witches broom
 Causal pathogen
 16SrI phytoplasma
 Presumed insect transmission
 Spread through infected planting material
 Symptoms
 Stunting
 Leaf proliferation
 Yellowing / discoloration
 Yield impact
 Average 10-15% yield losses
 25-30% reduction starch content / quality
 Plant death
 General crop loss

10. Monitoring

11. Monitoring efforts
 Regional scouting
 Vietnam/Laos/Cambodia/Myanmar/Thailand
 2014 dry season
 ~450 cassava fields
 Simple survey protocol
 Standardized across countries/regions
 Quick screening
 Mealybug species complex
 Cassava witches broom
 Other phytosanitary constraints
 PCR-based confirmation CWB
 Anticipated outcome
 Early detection > Rapid response
 Sustained monitoring > Safe areas

12. Pest monitoring - 2014
Phenacoccus manihoti Paracoccus marginatus Long-tailed mealybugs

13. Pest monitoring - 2014
Long-tailed
species
P. manihoti P.
marginatus
% CM-infested
plants / field
78.2 ± 26.7 4.0 ± 4.9 68.2 ± 17.5
# mealybugs
/ plant
36.6 ± 27.8 8.4 ± 8.2 35.7 ± 19.1
Long-tailed
species
P. manihoti P.
Long-tailed
species
marginatus
P. manihoti P.
marginatus
% CM-infested
plants / field
24.5 ± 19.9 35.9 ± 29.4 39.6 ± 25.5
# mealybugs
/ plant
2.7 ± 1.6 13.7 ± 17.0 14.8 ± 31.3
% CM-infested
plants / field
49.5 ± 28.5 16.3 ± 14.3 26.7 ± 16.1
# mealybugs
/ plant
9.8 ± 10.7 24.8 ± 26.5 13.6 ± 17.9

14. CWB monitoring - 2014

15. CWB monitoring - 2014
Kampheang
Phet
Field-level
estimate
Transect
walks
%
symptomatic
plants
17.7 ± 17.5 6.00 ± 6.00
% fields
infested
100 100
Quang
Ngai
Field-level
estimate
Transect
walks
%
symptomatic
plants
43.9 ± 24.5 39.5 ± 26.1
% fields
infested
90 90
Kracheh Field-level
estimate
Transect
walks
%
symptomatic
plants
44.1 ± 20.9 56.2 ± 26.9
% fields
infested
100 100

16. Capacity building

17. Capacity building
Morphology-based
identification
Monitoring & symptom
recognition
Expert workshop &
awareness-raising
Extension officer training

18. Applied research

19. Applied research – mealybug complex
CATAS - Haikou, China
Laboratory research
Associational resistance to P.
madeirensis ~ cassava companion
crops
HUAF – Hue, Vietnam
Laboratory research
Effect of plant nutrition on P.
manihoti and Anagyrus lopezi
development and fitness
PPRI – Tay Ninh, Vietnam
Field research
Mealybug – parasitoid –
hyperparasitoid food webs in
cassava plots of differing size
KU - Bangkok, Thailand
Field research
Effect of mealybug
infestation level and plant age on
cassava yield
RYFCRC- Rayong, Thailand
Laboratory research
Compatibility of thiamethoxam
stake dips with mealybug biological
control

20. Applied research - CWB
HARC – Dong Nai, Vietnam
Laboratory research
Evaluation of dry/wet heat
treatments for CWB-infested
cassava planting material
PPRI – Dong Nai, Vietnam
Field research
Membrane feeding assays to
identify potential insects vectors of
CWB phytoplasma
RYFCRC – Rayong, Thailand
Field research
Temporal fluctuations in species
composition and abundance of
plant- / leafhoppers in CWB-infested
fields

21. Roll-out & Extension

22. P. manihoti invasion of Indonesia
2010
production
areas
Forecasted
P. manihoti
impact
2010 2014

23. Parasitoid introduction & release
Indonesia enlists wasps in war on crop killer (ABC News)
Wasp ‘SWAT’ team to the rescue of Indonesian cassava
crop (Business Insider)
Parasitic wasps unleashed on insect pest (Inside
Science)
Des guêpes face aux cochenilles pour sauver le manioc
(Liberation)

24. Farmer-to-farmer video
 Mealybug prevention & control
 Audience
 Extension workers, farmers
 Farmer-to-farmer educational
video
 Curative / preventative tactics
 Healthy planting material
 Field sanitation & stake treatments
 Translated into 7 diff. languages
 Distributed through ‘agricultural
cinema’ – following ‘Going Public’
methodologies

25. Pest/disease research network
 Monitoring
 PPD (Vietnam), PPC, NAFRI (Laos), GDA
(Cambodia), DoA (Thailand), IPB
(Indonesia)
 Research
 PPRI, IAS, HUAF (Vietnam), Kasetsart
University, AIT & DoA (Thailand)
 Extension
 Farmer survey work: DoAE (Thailand),
RUA (Cambodia), NUoL & PPC (Laos)
 Extension: PPD (Vietnam), PPC (Laos),
GDA (Cambodia), DoAE(Thailand)

26. Thanks
Contact:
Kris A.G. Wyckhuys
k.wyckhuys@cgiar.org