ipm for pearl millet in the sahel: augmentative on-farm releases of parasitoids to control the...
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IPM for Pearl Millet in the Sahel: Augmenta5ve on-‐farm releases of parasitoids to control the millet head miner in the Sahel.
Malick Ba ICRISAT Niger
Pearl millet, Pennisetum glaucum (L.) R. Br., is the staple crop of the dry regions of Africa.
Pearl millet
3/26/15, 2:17 AM
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The millet head miner, Heliocheilus albipunctella (de Joannis) (Noctuidae),
The millet head miner damage
Ø Damage to the crop is due to larvae that feed on the panicle and prevent grain formaFon.
Ø As the larvae chew between the rachis and flowers, they liJ the destroyed flowers or developing grains, leaving a characterisFc spiral paKern on the millet head.
Ø Typical yield losses range from 40 to 85%
Ø Almost every year outbreaks of the MHM are observed in the Sahel especially on early-‐planted millet or early maturing material
The millet head miner damage
Management op5ons • Control with insecFcides is not realisFc for subsistence farmers because of prohibiFve cost and risk to health and the environment.
• Cultural management has limited applicability
• Host Plant Resistance is sFll under invesFgaFon
• EffecFve biocontrol agents are available
Biological control
• The braconidae parasitoid wasp Habrobracon (=Bracon) hebetor Say naturally inflicted significant mortality to MHM.
• But parasiFsm occurs late in the season when most of the panicle are damaged
H. Hebetor developing on larvae of the MHM
Augmenta5ve biological control • Colony of H. hebetor are established and maintained in the
laboratory on an alternate host, the rice moth Corcyra cephalonica
• C. cephalonica is reared on a mixture of millet flour and millet grains
• The parasitoids are released in 15 cm × 25 cm jute bags (+200 g of millet grains + 100 g of millet flour + 25 larvae of the rice moth Corcyra cephalonica (Stainton) + two mated H. hebetor females)
• The jute bags are suspended to the ceiling of tradiFonal straw granaries
How augmenta5ve releases are made?
§ Parasitoid offspring’s escaped through the jute meshes and straw granaries and dispersed to millet fields
• A set of 15 bags are used to cover 5km2 area
• Roughly an iniFal number of 1000 parasitoids are released
0
5
10
15
20
25
30
6 7 8 9 10 11 12 13 14
Num
ber o
f parasito
ids e
merging from
the
jute bags
Days aKer confinement
Daily H. hebetor adults emerging from the jute bags
Total: 70 parasitoids Emerging 5me: 8 days
Effec5veness in controlling the head miner
0
20
40
60
80
100
120
Burkina Faso Mali Niger
% parasi5zed larvae
H. hebetor releases villages Control (no releases)
0
20
40
60
80
100
120
Burkina Faso Mali Niger
% parasi5zed larvae
H. hebetor releases villages Control (no releases)
2007
2008
Challenges
• Place of deployment of jute bag for communiFes where granaries are made of clay, which could not enable parasitoids to escape?
• The quanFty of millet flour/grain needed for formulaFng the parasitoid bags?
• Thus, we invesFgated: – effects of placing jute bags directly within millet fields on the
parasiFsm of MHM. – Reducing the seize of the jute bag
Reduc5on of bags size by 80%
0
4
8
12
16
20
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
Num
ber o
f em
ergi
ng H
. heb
etor
per
ba
g
Number of days after confinement within jute bags
15 cmx25cm bags
7 cmx10cm bags
T=57 T=70
Ba et al., 2014 Biocontrol
Ba et al., 2014 Biocontrol
Type of bag
Number parasitoids emerged (Mean ± SE)
% Parasi5sm C. cephalonica (Mean ± SE)
H. Hebetor development 5me (Mean ± SE)
25 x 15 cm 57.10 ± 5.01 80.77 ± 0.17 12.15 ± 0.34
10 x 7 cm 69.80 ± 5.57 87.19 ± 0.08 11.64 ± 0.31
T= -‐1.69 DF= 38 P= 0.10
T= -‐1.72 DF= 38 P= 0.09
T= -‐1.08 DF=118 P=0.27
Reduc5on of bags size by 80%
A B
C
a b
c
0 10 20 30 40 50 60 70 80 90
100
7x10cm jute bags 15x25cm jute bags Control (no parasitoid released)
% M
HM
larv
ae p
aras
itize
d
by H
. heb
etor
Burkina Faso Niger
Ba et al., 2014 Biocontrol
Reduc5on of bags size by 80%
Displaying bags within millet fields
A
A
B B
0 10 20 30 40 50 60 70 80 90
100
2011 2012
% M
HM larvae parasi5zed by H. h
ebetor
Years
Parasitoid bags directly placed within millet crop
Control (no parasitoid released)
Ba et al., 2014 Biocontrol
Completely damaged panicles Saved panicles
Economic advantages Up to 30% grain yield gain
Baoua et al, 2013. J. Appl Ento
Way Forward
• Establish parasitoid coKage industry
• Use of egg parasitoids for enhancement of the biocontrol program
• Use of pearl millet tolerant varieFes
Thank you!