MLN Workshop: Role of vectors and their host plants in maize lethal necrosis epidemiology -- J...
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Transcript of MLN Workshop: Role of vectors and their host plants in maize lethal necrosis epidemiology -- J...
![Page 1: MLN Workshop: Role of vectors and their host plants in maize lethal necrosis epidemiology -- J Nyasani et al](https://reader037.fdocuments.us/reader037/viewer/2022103018/55a6e8f31a28ab06328b48bd/html5/thumbnails/1.jpg)
Role of vectors and their host plants in the epidemiology of maize lethal
necrosis disease
Nyasani, JElizabeth, KSubramanian, S
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Complexities of MLN Epidemiology
Maize chlorotic mottle virus
(MCMV)
Sugarcane mosaic virus
(SCMV) or other cereal
potyvirus
Maize
Vectors of MCMV –Thrips,
beetles and others?
Vectors of potyviruses – Aphids and
others ?
Maize - MLN
Alternate hosts – Weeds or cultivated crops
Natural enemies of vectors
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Information so far on insect vectors
• Maize chlorotic mottle virus• Corn thrips, Frankliniella williamsi• Cereal leaf beetle, Oulema melanopa• Corn flea beetle, Chaetocnema
pulicaria• Rootworms, Diabrotica spp
• Sugarcane mosaic virus• Aphids, Rhopalosiphum maidis
Source: Pest net and Fotoopa
What else??
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Distribution of potential vectors: Kenyan situationKenyan situation
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Distribution of thrips on maize in Kenya (Jun-Sep 1 4)
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Distribution of aphids on maize in Kenya (Jun-Sep 1 4)
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Distribution of beetles on maize in Kenya (Jun-Sep 14)
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Distribution of stemborers on maize (Jun-Sep 14)
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Distribution of leafhoppers on maize (Jun-Sep 14)
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Distribution of whiteflies on maize (Jun-Sep 14)
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Confirmed vectors of MCMV
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Corn thrips
Onion thrips
Thrips
Common blossom thrips
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Distribution of vector thrips in east Africa
Frankliniella williamsi Frankliniella schultzei
Thrips tabaci
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Other vectors - Beetles
Curculionid weevil Sap beetle
Cereal leaf beetle
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Vectors of SCMV
Cereal leaf aphid
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Host range of MCMV and SCMV and their vectorsSCMV and their vectors
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Role of host plants spread of MCMV and SCMV
A: Role of wild grasses in spread of SCMV
B: Role of finger millet in spread of MCMV
A B
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Presence of MCMV and SCMV in non-maize plants
Finger millet showing mottle symptomTested positive for MCMV by ELISA and RT-PCR
A wild grass showing chlorotic and streak symptomsTested positive for SCMV by ELISA and RT-PCR
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Presence of MCMV and SCMV in wild and domesticated grasses, and cereal crops
Plant species MCMV SCMV Wild grassesDigitaria abyssinica + +Cynodon dactylon + + Pennisetum cladestinum + + Digitaria velutina + + Cyperus rotundus + -Bracharia brizantha + + Bracharia brizantha + +
Domesticated grassesSaccharum officinarum + +Pennisetum purpureum + -
CerealsEleusine coracana + + Sorghum bicolor - +
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Vector management: Thrips
16
18
Nu
mbe
r of t
hrip
s pe
r mai
ze p
lan
t
Control (seed treatment alone)
Ctrl +soil applic of Trichoderma+Nurelle-D spray at 2 weeks interval
Ctrl+soil applic of Trichoderma+Maetarhizium spray at 2 weeks interval
Ctrl+soil applic of Trichoderma+Metarhizium spray-Nurelle-D-Metarhizium spray
Ctrl+Nurelle-D spray at 2 weeks interval
Ctrl+Metarhizium spray at 2 weeks interval
Ctrl+soil applic of Trichoderma alone
0
2
4
6
8
10
12
14
Week 1 Week 2 Week 3 Week 4 Week 5 Week 6
Nu
mbe
r of t
hrip
s pe
r mai
ze p
lan
t
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Vector management: Beetles
1.6
1.8
Nu
mb
er o
f be
etle
s p
er
ma
ize
pla
nt
Control (seed treatment alone)
Ctrl +soil applic of Trichoderma+Nurelle-D spray at 2 weeks interval
Ctrl+soil applic of Trichoderma+Maetarhizium spray at 2 weeks interval
Ctrl+soil applic of Trichoderma+Metarhizium spray-Nurelle-D-Metarhizium spray
Ctrl+Nurelle-D spray at 2 weeks interval
Ctrl+Metarhizium spray at 2 weeks interval
Ctrl+soil applic of Trichoderma alone
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
Week 1 Week 2 Week 3 Week 4 Week 5 Week 6
Nu
mb
er o
f be
etle
s p
er
ma
ize
pla
nt
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Vector management: Aphids
10
Nu
mbe
r of a
phid
s pe
r mai
ze p
lan
t
Control (seed treatment alone)
Ctrl +soil applic of Trichoderma+Nurelle-D spray at 2 weeks interval
Ctrl+soil applic of Trichoderma+Maetarhizium spray at 2 weeks interval
Ctrl+soil applic of Trichoderma+Metarhizium spray-Nurelle-D-Metarhizium spray
Ctrl+Nurelle-D spray at 2 weeks interval
Ctrl+Metarhizium spray at 2 weeks interval
Ctrl+soil applic of Trichoderma alone
0
2
4
6
8
Week 1 Week 2 Week 3 Week 4 Week 5 Week 6
Nu
mbe
r of a
phid
s pe
r mai
ze p
lan
t
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Concluding remarks
�Corn thrips, common blossom thrips, sap beetles, and onion thrips are vectors of MCMV
�Corn leaf aphid is a vector of SCMV
�There could be other vectors for the two viruses
�The distribution of the vectors differs with season and plant stageand plant stage
�Wild and domesticated grasses serve as alternative host of MCMV and SCMV
�The suitable areas for the grasses are mainly located in the key maize growing counties
�Biopesticides are effective in the management of vectors of viruses causing MLN
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Way Forward: Capacity building for detection, monitoring and management of MLN and its vectors
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Acknowledgements
Kenya Agricultural Productivity and Agribusiness Project