ipm for cowpea

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

IPM for cowpea

Manuele Tamò

insect ecologist

R4D week, Nov 25, 2009


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

2 spray No spray

Variety Grain

(kg/ha)

Fodder (kg/ha)

Grain (kg/ha)

Fodder (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

• no reliable sources of resistance in crossable species

• wide crosses unsuccessful

• use of susceptible varieties possible with chemical control


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 IPE* yield (kg/ha) yield (kg/ha) yield (kg/ha) yield (kg/ha) ___________________________________________________________ IT95M-268-1-4 1530.7 1377.4 1479.5 1350.8 25.0

IT95M-305-1 1479.5 1313.6 1328.6 1190.2 26.5

IT95M-190-4 1539.1 1348.2 1303.2 1123.6 26.8

IT95M-7 1567.0 1520.7 1256.1 1192.7 35.5

IT95M-190-1 1349.0 1233.6 1192.7 980.2 26.8

IT95M-309-1 1490.3 1450.3 1177.3 1091.5 23.0

IT95M-249-1 1502.8 1425.7 1127.7 935.6 27.5

TVU14476 (CK) 1207.3 1120.2 994.8 915.6 30.0

IT86D-715 (CK) 1034.4 876.8 673.1 574.3 20.0

IT86D-719 (CK) 1012.3 821.4 614.3 457.6 22.5

LSD 5% 310.4 303.3 380.8 355.2 6.8

CV % 16.1 17.1 24.1 25.1 17.7

__________________________________________________________

*IPE = Pod evaluation index


1 2 3 4 5 6 7 8 9

75 Kd

50 Kd

37 Kd

Pet YL OL SEP PET Poll Pod Imm Mat

Seed Seed

The Bt-protein is found in most green

organs of transgenic cowpea

Cry 1Ab*

*LSUCourtesy: T.J. Higgins, CSIRO


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


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)

Prospective NTO studies on M. vitrata natural enemies


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

0

10

20

30

40

50

Lc Ls Ps Pp Tp Vu

Phanerotoma leucobasis

Braunsia kriegeri

Maruca vitrata larval parasitism rates on different host plants in Benin


Apanteles taragamae Viereck (Hymenoptera, Braconidae)

On-going biological and ecological studies

0

2

4

6

8

10

12

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

days

mx

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

lx

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

(OB/ha)

% mortality

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 !


TreatmentstrExposure time

2 h 24 h

Control 0 b 0 b

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***

Presence of MaviMNPV OB in larvae of Maruca vitrata as a

function of different contamination methods using 2h and 24h virus

exposure time.

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


MR-cowpea Biopesticides as

tools in IRM

‘IPM model’ for Maruca vitrata

Alternative host

plans (BC and IRM)

Novel BC agents


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


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

Host plant resistance


Biodiversity studies: natural enemies of M. sjostedti

Larval parasitoid: Ceranisus menes Walker

Predator: Orius albidipennis Reuter

0.5 mm

Egg parasitoid: Megaphragma sp.


0 1 2 3 4 5

%

V. unguiculata

P. santalinoides

L. sericeus

L. cyanescens

T. candida

Parasitism rates of M. sjostedti larvae by C. menes on

selected host plants

31754

7590

8357

5671

8222


Discovery of the thrips parasitoid Ceranisus femoratus in

Cameroon

V. unguiculata

C. pubescens

D. guineensis

T. candida

5841

130

2315

1110

Important parasitism rates on wild host plants


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

0

50

100

150

200

250

Lonchocarpus

sericeus

Lonchocarpus

cyanescens

Pterocarpus

santalinoides

Tephrosia

bracteolata

Tephrosia

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

Technology

local braunsia kriegeri

vitrata parasitoids

vitrata egg

local pristomerus

local testudobracon

local bracon sp

local dolichogenidea

cowpea ipm