Presentation on theme: "DISTRIBUTION OF MAIZE LETHAL NECROSIS, ITS VECTORS AND HOST PLANTS IN MAJOR MAIZE GROWING AREAS OF UGANDA PhD proposed research in Uganda by Mudde Barnabas."— Presentation transcript:
1DISTRIBUTION OF MAIZE LETHAL NECROSIS, ITS VECTORS AND HOST PLANTS IN MAJOR MAIZE GROWING AREAS OF UGANDAPhD proposed research in UgandabyMudde Barnabas PhD student, University of NairobiPresented During The Workshop To Develop Strategic Plan For Maize Lethal Necrosis Disease For Eastern And Central Africa, Jacaranda Hotel, Nairobi, Kenya 21st -23rd August, 2013Supervisors1. Prof . Olubayo Florence, Faculty of Agriculture, University of Nairobi2. Dr. Miano Douglas, Faculty of Agriculture, University of Nairobi3. Dr. Asea Godfrey, National Agricultural Research Organisation (NARO)
2BackgroundMaize Zea mays (L.) is one of the chief starchy cereal crops in East AfricaIt is the vital staple for over 70 million peopleUganda ranked 10th in AfricaAnnual production estimate at 1,373,000 tonnesAnnual yield is 1.5 tons per hectareLow yields majorly attributed to biotic constraintsMajor biotic constraints include diseases caused byFungiBacteriaVirusesMost important viruses areMaize streak virus, Maize rough dwarf virusAnd the new Maize lethal necrosis
3Maize lethal necrosis disease Maize Lethal Necrosis disease (MLN) first identified in USA in 1976; In East Africa from Kenya and Tanzania (2011); In Uganda (2012).Symptoms include; drying of leaves, premature plant death; failure to tassel / sterility in male plants; malformed /no ears; premature drying or rotting of cobsPotential yield losses %. (Wangai et al., 2012)MLN caused by double infection with Maize chlorotic mottle virus (MCMV) and any of cereal viruses in Potyviridae group; Sugarcane mosaic virus (SCMV), Maize dwarf mosaic virus (MDMV) or Wheat streak mosaic virus (WSMV).MLN-causing viruses are transmitted by several insect vectors. MCMV (thrips and beetles) MDMV and SCMV (aphids).Alternate hosts of MLN causing viruses include; Maize, sugarcane, grasses of family poaceae, sorghum, millet and johnson grass.
5Problem statementMaize Lethal Necrosis disease (MLN) stands out as greatest threat to African food security crop (maize).In 2012, this MLN disease outbreak was first reported in Busia district in eastern Uganda, it is not known to what extent this disease is now prevalent and distributed in Uganda.It is not known which maize viruses of the Potyviridae group in Uganda could be combining with MCMV to cause the MLN symptoms observed in maize fields so far.Apart from maize, the maize lethal necrosis causing viruses are haboured by alternate plant hosts. The potential plant hosts for MLN causing viruses in Uganda not known.The vectors of the MLN-causing viruses in Uganda are not known and their virus transmission efficiency.Plant virus epidemics are multi-component systems resulting from interactions between the virus (es), vectors and host plant (s).A full understanding of the epidemiology of MLN disease is critical for development of sustainable management strategies
6Objectives General Objective To provide a better understanding of the epidemiology, host plants, vector range of MLN disease for improved controlSpecific objectives of the study1. To establish the distribution and incidence of MLN in Uganda2. To determine alternate hosts of MLN causing viruses in Uganda3. To identify potential insect vectors of MLN causing viruses in Uganda4. To determine transmission efficiencies of vectors of MLN causing viruses in Uganda
7Survey in 13 districts of Uganda MethodologySurvey in 13 districts of UgandaMaizeAlternate hostsELISA and PCRObjective 1Objective 2Collection of potential vectors of MLN causing virusesSpecies identificationELISA and PCR and transmissionObjective 3Conduct studies to determine efficiency of transmission of different species of confirmed vectors of MLN virusesObjective 4
8MethodologyObjective. 1 . Distribution, incidence and severity of MLN in major maize growing districts of UgandaData from 13 major maize-growing districts of UgandaDisease incidence: Estimate of percentage of maize plants infestedSeverity assessed using a 1 to 5 scale by Biswanath et al. 2013GPS coordinates recorded
9Methodology cont’dActivity 1.1. Serological and molecular detection of MLN in maize samplesLab studies at National Crop Resources Research Institute, Namulonge in Uganda.ELISA against MLN causing viruses (MCMV, SCMV, MDMV, WSMV) as well as antibodies against the entire Potyvirus genus (AGDIA, Elkhart,IN).Confirmation with reverse transcription-polymerase chain reaction (RT-PCR) using specific primers (Wangai et al., 2012)
10Methodology cont’dObjective 2: Identification of alternate plant hosts of MLN in UgandaAlternate MLN host plants collected from confirmed hotspots of MLN in Uganda.Identified to species level in collaboration with Botany and Zoology department of Makerere University Institute of Environment and Natural ResourcesELISA against MLN causing viruses (MCMV, SCMV, MDMV, WSMV) as well as antibodies against the entire Potyvirus genus (AGDIA, Elkhart,IN).
11Methodology cont’dObjective 3: Identification of potential insect vectors in UgandaActivity 3.1. Vector collectionSampling vectors from confirmed hotspots of MLN in Uganda.Potential vectors colonizing maize will be identified to species level in collaboration with ICIPE.Insect vector viral content MLN causing viruses will be determined using Enzyme Linked Immunosorbent Assay as previously described by Chu and Francki, (1982).Real time PCR will be also be used to quantify viral load in potential vectors
12Methodology cont’dObjective 4: Determine transmission efficiencies of potential vectors in Uganda to transmit MLNVectors transferred to MLN-infected 3 week old maizeFor each insect vector, 3 species selected for transmission studiesMCMV symptoms noted in seedlings at 5, 10, 15, 20, after feedingViral content will be measured at each of these stages using ELISAPercent transmission rates based on number of infected plants out of total observed
13Expected budget and output Budget : USD 90,000Outputs1. Incidence and distribution of MLN in Uganda established.Knowledge of alternative hosts and vectors of MLN causing viruses prevalent in Uganda3. At least 4 scientific papers and PhD thesis published.
14Acknowledgements NARO Government of Uganda Development Partners University of Nairobi