Landbruksentomologi: OPPGAVER I UTLANDET

May-Guri Sæthre

1. Plantevernet å ha et nært samarbeid med International Institute of Tropical Agriculture (IITA), med hovedkvarter i Ibadan, Nigeria. Det er utarbeidet et Memorandum of Understanding med IITA. IITA har forskningsstasjoner og nettverk over hele Afrika, og flere typer hovedoppgaver er mulige. Se nedenfor

Stedlig veileder: May-Guri Sæthre

2. Endophyte-enhanced banana tissue culture plants

Student topics


Background

Banana is a vital crop for the Great Lakes region in Africa. In Uganda alone, daily per capita consumption averages almost half a kilogram. The types of banana that are grown in Uganda are physiologically and genetically unique, and are called East African highland bananas, used for cooking or brewing. The banana weevil, Cosmopolites sordidus, and the burrowing nematode, Radopholus similis, are among the most important pests of East African highland bananas. Both pests are soil-borne, and lead to destruction of underground tissues, reducing yield and ultimately destroying plant anchorage.

Banana in the region is traditionally propagated by means of suckers, which are cut off rhizomes with a shoot attached. The problem is that these suckers are full of soil-borne pests, especially banana weevils and nematodes, and that by consequence, yield and plantation longevity are drastically reduced, with dire consequences for food security in the region.

In the laboratory, banana can now be produced axenically through tissue culture. Tissue culture banana plants are by definition a pest and disease free planting material. This banana propagating technique is widely adopted in the world, but is only now beginning to see the light in Africa.

However, all plants, including banana, contain endophytes, which are naturally occurring microorganisms inside the plant that protect the plant from pests and diseases and that enhance plant growth. By producing banana plants aseptically in the laboratory through tissue culture, the plants do not only loose the pests and diseases, but they also loose the endophytes. Our project has as purpose to reintroduce the endophytes into the banana tissue culture plants to restore the natural equilibrium. In other words, incorporation of endophytes extends the benefits of clean planting material.

During the last seven years, endophytes have been isolated and screened, and the best endophyte candidates have been incorporated in banana tissue culture plants and tested against banana weevils and nematodes in screenhouse and field experiments. Presently, our project is moving towards applied research, such as transfer of endophyte-enhanced banana tissue culture technology to commercial tissue culture laboratories for on farm research.


Student topic 1 1:
Optimal colonization of endophytes in banana tissue culture plants
In order to be a commercial feasibility, it is crucial that the technique of inoculating endophytes in banana tissue culture plants is perfected. At present, endophytes are incorporated artificially when tissue culture plants leave the laboratory to the screenhouse for hardening: plant roots are broken, after which plants are treated with a small inoculum of solid substrate containing the endophyte. It is paramount that high colonization levels are obtained, while making sure that the technique is easily incorporated in existing practices of commercial tissue culture laboratories. Many issues are presently unsolved. Is it essential that root tips are broken to facilitate endophyte entry? How important is development of high root biomass for optimal inoculation? Should we use a solid substrate or a liquid substrate? Might it be possible to incorporate endophytes into plants that are still in test tubes in the laboratory? Which technique offers the lowest cost/benefit ratio for a commercial laboratory? It is envisaged that the student will work closely with AGT (a commercial tissue culture laboratory in Uganda) and JKUAT (a semi-commercial tissue culture laboratory in Kenya).

Other student topics

Performance and farmers’ acceptance of tissue culture plants in Uganda
This project depends on farmers accepting tissue culture plants. Unfortunately, in Uganda, this has proven to be a slow process. Farmers are reluctant to abandon the use of conventional planting material for more expensive tissue culture plants, and are not convinced that, in the long run, tissue culture plants will outperform any other type of planting material. The student will identify socio-economic opportunities and bottlenecks of tissue culture in Uganda, in order to further the project.

Endophyte-enhanced tissue culture banana against other nematode species
Until now, we have only focused on Radopholus similis, which is worldwide the most damaging nematode. However, endophytes should be equally effective against other nematode species that are very important in the region, such as Helicotylenchus multicinctus, various Meliodogyne spp. and various Pratylenchus spp.

Endophyte-enhancement of dessert and improved banana varieties
East African highland bananas have been the main focus thus far. However, due to enhanced quality and uniformity, tissue culture technology offers farmers the chance to market their produce for domestic and international markets. As such, endophyte enhancement should be equally investigated for use in other banana varieties.

Distribution and spread of endophytes in banana tissue culture plants
Banana is a perennial crop. We have mainly focused on the first crop cycle, but it is hoped that the benefits of endophytes spill over in subsequent crop cycles. Molecularly and biochemically marked endophytes will be available to study distribution and spread of endophytes within the banana plant. Especially interesting is knowing whether or not endophytes colonize suckers that originate from the motherplant.


About the location and the team

Although the project is based in Sendusu, Uganda, it includes eight partners in five countries (Uganda, Kenya, the Netherlands, Germany and South Africa). We are well-equipped with highly qualified technicians, 4 WD vehicles, excellent laboratory and computer facilities, and a vast group of students. The incoming student will work out of Sendusu, Uganda, which is about 45 min drive from Kampala. The student will have access to the staff van that commutes daily. He/she can live in Sendusu or Kampala. Kampala is a vibrant and very safe city that boosts excellent facilities. Immediate supervision will be conducted by Dr. Danny Coyne (nematologist) and Dr. Thomas Dubois (biocontrol specialist). The student will be able to interact with IITA scientists in other disciplines (market economy, plant breeding, plant pathology, agronomy, etc.) and work closely with NARO, Uganda’s national agricultural program. For more information please contact d.coyne@cgiar.org or t.dubois@cgiar.org.



3. Studies on ecology of Xanthomonas campestris pv musacearum (Xcm)
This bacteria causes wilt of banana and plantains, two crops of major importance for food and income in the Great Lakes region of East and Central Africa. In addition to colonizing plant tissues, the pathogen can be found on plant surfaces, on ooze extruded from plants and on insect vectors. Bacterial cells are also released in large numbers into soil and water when infected plant tissues rot.
Understanding the factors that influence survival of the pathogen in these diverse environments is essential for disease management. Of importance also is knowledge on how Xanthomonas interacts with other microorganisms in the same ecological niches and how these interactions could be exploited for disease management.

An MSc topic in this area could examine physico-chemical attributes of various ecological niches that would be of importance in the ‘life’ of Xcm and examine how survival of bacterial cells varies as conditions change. Research could also look into microbial populations in different niches and study what could be manipulated to make the environment unfavorable for Xanthomonas. The research would be carried out in Uganda.

Linkages with a lab in Norway where microbes (mostly bacteria) can be rapidly characterized and identified would be beneficial, but not a requirement.





4. Insect pathogenic fungi regulating insect- and mite populations in Central America (Nicaragua, Costa Rica and Guatemala)
Background: Insect pathogenic fungi are very important naturally occurring mortality factors of plant pest insects and mites. About 750 different fungal species are known to infect insects, and most fungal species that infects insects or mites belong to the class Hyphomycetes or the order Entomophthorales. Species belonging to the class Hyphomycetes mainly causes natural infection and epizootics in soil dwelling pest insects and mites. Fungal species belonging to Entomophthorales mainly cause natural infection in foliar insect and mites. Management practices (monoculture, pesticide spraying, use of fertilizer, shading etc) are important factors for the natural occurrence and prevalence of insect- and mite pathogenic fungi of insects and mites. No studies on the natural occurrence of insect- and mite pathogenic fungi in the important group Entomophthorales have, however, been conducted in Central America. The aim of this thesis is therefore to build up competence and start work on this important group of natural enemies.

Thesis: Several approaches are relevant, and a specific approach must be made based on the student’s field of interests. Collection of insects and mites in different cropping systems and identification of both insect, mites and fungi down to species level will be important in this work. The effect of different cropping systems (e.g. different pasture systems) on species diversity and occurrence is also relevant. Travel expenses will be granted by Statens Lånekasse for utdanning upon application from the student. Noragric students have their own agreements for fieldwork. Financial support of materials needed for field and laboratory studies will be covered by the project benefiting from the work. It should preferably be a 60 ECTS credits Master thesis, but 30 ECTS Master thesis is also of interest.

Supervisor in Norway: Ingeborg Klingen

5. Skadedyr i grønnsaker i Vietnam
Bakgrunn: Planteforsk Plantevernet har et 3-årig (2005-2007) NORAD-finansiert prosjekt i Vietnam: "Integrert plantevern på grønnsaker i Vietnam". Formålet er å redusere bruken av plantevernmidler. I 2000-2005 utførte fire UMB-studenter feltarbeidet i Vietnam til hovedoppgaven. Vi ønsker nye studenter velkommen til å delta med hovedoppgaver i prosjektet.

Oppgave: Flere oppgaver er aktuelle, bl.a. biologi og bekjempelse av skadeinsekter på agurk, tomat og bønner. Foreløpig har vi konsentrert oss om minerfluer i blader og stengler. Andre aktuelle temaer er vertspreferanse, parasitter på disse insektene og fastsettelse av skadeterskler. Dessuten vil det være ønskelig å undersøke effekten av såkalte Farmer Field Schools på bøndenes bruk av integrert bekjempelse mot skadeinsekter.

Stedlig veileder: Trond Hofsvang, Arild Andersen


6. Nematoder i subtropiske og tropiske områder

Det er viktig å ta i betrakting at i de fleste tropiske land er jordbrukproduksjonen en viktig del av brutto nasjonalprodukt. I subtropiske og tropiske områder er det enda mange uløste problemer knyttet til planteparasittære nematoder. Potensielle oppgaver innen dette feltet er avhengig av støtte fra NORAGRIC eller andre finansieringskilder.

Det er muligheter for hovedoppgaver i Bolivia og Costa Rica:

Bolivia: Nematoder i jordbruksvekster/hagebruksvekster i Tiahuanaco.
Det kan søkes økonomiske støtte fra SAIH/ NORAGRIC.

Costa Rica: Nematoder i bananer, bekjempelse m.m.
Oppgave i samarbeide med Corporación Bananera Nacional
Det kan søkes økonomiske støtte fra NORAGRIC.

Stedlige veiledere: Christer Magnusson/Ricardo Holgado




Oppdatert: 01.01.07
Utskriftsvennlig versjon : Arkiv : Tips en venn