IPM for cowpea

IPM for cowpea

Manuele Tamò
insect ecologist

R4D week, Nov 25, 2009

International Institute of Tropical Agriculture – Institut international d’agriculture tropicale – www.iita.org

Strategic vision for cowpea IPM (5-10 years)

Preventive side:
• Host plant resistance (incl. transgenics)
• Conservation biological control
Curative side:
• Inoculative and augmentative biological control
• Bio-pesticides
• Synthetic insecticides


The legume pod borer, Maruca vitrata


Insect resistant cowpea – conventional breeding

• no reliable sources of resistance in crossable species
• wide crosses unsuccessful
• use of susceptible varieties possible with chemical control

2 spray No spray

Variety Grain Fodder Grain Fodder
(kg/ha) (kg/ha) (kg/ha) (kg/ha)

IT90K-277-2 2697 2219 549 3236

IT95K-231-1 2235 2619 312 3043

IT95K-193-12 2020 1513 496 1462

Dan lla (Local) 1407 3050 14 3677


Table 2
Performance of cowpea Breeding Lines in Ibadan During the Second Season
(September to November) of 1998
______________________________________________________
Spray No Spray
_______________________

Cowpea Line Total seed Good seed Total seed Good seed IP
yield (kg/ha) yield (kg/ha) yield (kg/ha) yield
(kg/ha)
___________________________________________________________
IT95M-268-1-4 1530.7 1377.4 1479.5 1350.8 2
IT95M-305-1 1479.5 1313.6 1328.6 1190.2 2
IT95M-190-4 1539.1 1348.2 1303.2 1123.6 2
IT95M-7 1567.0 1520.7 1256.1 1192.7 3
IT95M-190-1 1349.0 1233.6 1192.7 980.2 2
IT95M-309-1 1490.3 1450.3 1177.3 1091.5 2
IT95M-249-1 1502.8 1425.7 1127.7 935.6 2
TVU14476 (CK) 1207.3 1120.2 994.8 915.6 3
IT86D-715 (CK) 1034.4 876.8 673.1 574.3 2
IT86D-719 (CK) 1012.3 821.4 614.3 457.6 2
LSD 5% 310.4 303.3 380.8 355.2
CV % 16.1 17.1 24.1 25.1 1
__________________________________________________________
*IPE = Pod evaluation index


The Bt-protein is found in most green
organs of transgenic cowpea

1 2 3 4 5 6 7 8 9
75 Kd

50 Kd
*
Cry 1Ab
37 Kd

Pet YL OL SEP PET Poll Pod Imm Mat
Seed Seed

Courtesy: T.J. Higgins, CSIRO *LSU

Bt-mediated effect on M. vitrata parasitoids

- using different doses of Cry1Ab
toxin on Phanerotoma leucobasis

- Parasitoid egg inserted in M.
vitrata egg, but development of
parasitoid larva only in late 1-st
instar
- substantial mortality of developing
parasitoids only when exposed to
LD95


Prospective NTO studies on M. vitrata natural enemies

Other parasitoids to be studied:
-Trichogrammatoidea eldanae (egg, local)
- Braunsia kriegeri (larva, local)
- Pristomerus sp. (larva, local)
- Bracon sp. (larva, local)
- Dolichogenidea sp. (larva, local)
- Testudobracon sp. (larva, local)
- Apanteles taragamae (larva, exotic)
- Bassus aper (larva, exotic)
- Nemorilla maculosa (larva, exotic)


Strategy for deploying biocontrol agents:
Exotic parasitoids:
• overall reduction of the population pressure,
particularly on wild host plants during the off-
season
MaviMNPV:
• to be used like a biopesticide for inundative
biological control e.g. once pheromone derived
threshold is reached


Ecology studies
Major alternative host plants in moist savannas of West Africa

Pterocarpus santalinoides Lonchocarpus cyanescens Lonchocarpus sericeus
Tephrosia candida

Population ‘migration’ of M. vitrata based on available
data from light traps and host plant surveys: implication
for control strategies


Which biocontrol agents?
Local natural enemies of Maruca vitrata in West Africa

Braunsia kriegeri Phanerotoma leucobasis

Maruca vitrata larval parasitism rates on different host plants in Benin
50

40

Phanerotoma leucobasis
30
Braunsia kriegeri
20

10

0
Lc Ls Ps Pp Tp Vu


Apanteles taragamae Viereck (Hymenoptera, Braconidae)
On-going biological and ecological studies

12 0.7

10 0.6

0.5
8
0.4
mx

lx
6
0.3
4
0.2

2 0.1

0 0
1 2 3 4 5 6 7 8 9 10 11 12 13 14

days

Over 60% parasitism on Sesbania in Taiwan


Experimental releases

…but no direct evidence
of establishment yet on
wild vegetation


A serial killer: Maruca vitrata Nuclear
Polyhedrosis Virus (MaviMNPV)


MaviNPV: lab and cage studies at IITA-Benin

treatement % mortality
(OB/ha)

0.1000 9,12 c

2.1009 24,43 bc

2.1010 35,55 bc

2.1011 56,25 ab

2.1012 75,00 a

2.1013 87,92 a


Strategy for deploying biocontrol agents:
Exotic parasitoids:
• overall reduction of the population pressure,
particularly on wild host plants during the off-
season
Biopesticide MaviMNPV:
• to be used like a biopesticide for inundative
biological control


A. taragamae and MaviMNPV flying together !

+ = !!!!!


Presence of MaviMNPV OB in larvae of Maruca vitrata as a
function of different contamination methods using 2h and 24h virus
exposure time.
Exposure time
Treatmentstr
2h 24 h
Control 0b 0b
Ovipositor 0,91 a 0,96 a
Whole body 0,94 a 0,97 a
Diet 0,90 a 0,98 a
P>F <0,0001*** <0,0001***

Mechanical transmission using detached ovipositor and glass
capillaries demonstrated.
Another important discovery: at temperatures <25 C co-infected
larvae will be killed by the virus before parasitoids can form a cocoon


‘IPM model’ for Maruca vitrata

Novel BC agents

MR-cowpea Biopesticides as
tools in IRM

Alternative host
plans (BC and IRM)


New BMZ project: large biodiversity of M. vitrata
natural enemies in Asia and maybe in South America


Pulses-CRSP project: M. vitrata rearing for national
programs and farmer groups


M. vitrata happily feeding on germinating
cowpea grains


Rearing methodology with germinating cowpea grains is 25-30x less
expensive than standard artificial diet for the same larval output level !!!


The bean flower thrips, Megalurothrips sjostedti Trybom (Thys., Thripidae)

Photo: G. Goergen


Host plant resistance

Cultivars Damage index

First season Second season

Moussa local 2.06 c 3.42 cd

Sewe 2.06 c 3.42 bc

Sanzisabinli 2.13 c 1.93 d

TVu 1509 (RC) 2.38 c 3.25 cd

IT90K-277-2 4.88 b 3.67 cd

KVx404-8-1 4.88 b 4.67 b

IT91K-180 5.06 b 5.75 a

TVx 3236 5.13 b 5.17 b

Vita7 (SC) 7.56 a 7.59a


Biodiversity studies: natural enemies of M. sjostedti

Larval parasitoid: Ceranisus menes Walker

Predator: Orius albidipennis Reuter

0.5 mm

Egg parasitoid: Megaphragma sp.


Parasitism rates of M. sjostedti larvae by C. menes on
selected host plants

V. unguiculata 31754

P. santalinoides 7590

L. sericeus 8357

L. cyanescens 5671

T. candida 8222

0 1 2 3 4 5

%


Discovery of the thrips parasitoid Ceranisus femoratus in
Cameroon

Important parasitism rates on wild host plants

V. unguiculata 5841

C. pubescens 130

2315
T. candida
D. guineensis 1110


Laboratory rearing very labour intensive and expensive

2 mm


In-field mass rearing on Tephrosia candida


Megalurothrips sjostedti

Establishment of the exotic thrips parasitoid Ceranisus
femoratus 4 years after the initial releases in three
countries


Large dataset from Benin,
comparing multi-year data
before releases and 4 years
data after the releases

250

200

150

100

50

0
Lonchocarpus Lonchocarpus Pterocarpus Tephrosia Tephrosia
sericeus cyanescens santalinoides bracteolata candida

Average number of M. sjostedti larvae per inflorescence of
different host plant (blue: period 1992-95, red: period
2005-2007)


Ecological impact: up to 43% reduction of thrips population
on wild host plants
Economic impact: on-going collaboration with agro-
economists for developing ex-ante impact assessment
models

IPM approach for flower thrips

- Host plant resistance in available germplasm
- Improved biological control:
On wild hosts: Ceranisus femoratus
On cowpea: Amblyseius swirskii
- Biopesticides:
entomopathogens
botanical extracts


Cowpea aphid, Aphis craccivora


Aphid colonies
destroyed by
Neozygites fresenii
in the Oueme valley
(Benin) during
‘harmattan’
conditions


New ‘serendipitously’ introduced biocontrol agent:
Lysiphlebus testaceipes

So far observed in Benin and Ghana, not in Niger and Burkina yet
Interactions studies on-going

New technology for FFF?

Solar-powered MP3 players
- FFF can now be augmented
with messages regarding the
agricultural issues being
addressed.
- Such devices can be taken
back to the communities
where the messages can be
played repeatedly (biggest
advantage over rural radio
messages which are often
played only once)


IPM for cowpea

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