Photo above: © Real World Photography
Welcome to the first issue of the newsletter of the Plant, Animal and Human Health group of the Natural Resources Institute! The newsletter will be published twice a year and will provide an update on our wide range of activities. We hope that the information will be of interest to a broad group of researchers, practitioners and policy makers in the field of natural resource management. The main focus of our work is in developing countries, but many aspects are becoming increasingly relevant elsewhere.
In this opening issue we report some recent achievements of staff and students and highlight a representative selection of current research and development activities. These activities range from assisting farmers to reduce losses due to pests in key crops in Uganda and India to developing novel approaches to manage diseases of livestock and humans in Zimbabwe and China. In each case, the ultimate objective is to enable poor farmers to increase their incomes so that they can improve the quality of their lives.
Begomovirus disease management for sustainable |
Wet/dry crop rotation reduces malaria incidence in southwestern China |
Steve Torr and his co-authors from Canada and Zimbabwe have won an award for the best paper published during the last two years in the journal Medical and Veterinary Entomology, published by the Royal Entomological Society. Their paper shows how a molecular diagnostic technique, DNA fingerprinting, can be used to identify which animals within a herd of cattle are preferentially bitten by tsetse fly. Tsetse fly transmits trypanosomiasis, which causes major disease problems in cattle and humans. The research indicated that tsetse prefer to feed on older and larger cattle. The findings will help to ensure that insecticide-based control methods for trypanosomiasis are targetted more effectively and at a reduced cost.
For further information, please visit NRI's website at: http://www.nri.org/news/archive/newsarchive.htm#accolade
NRI offers an MSc in Natural Resources which is run by Dr Peter Burt and Professor Bob Cheke, with many of the courses taught by other colleagues in PAHH. The course, which has been running for five years in its current form, is of particular interest to students from developing countries. It explores the ways in which developmental needs can be met through better understanding and improved management of renewable natural resources, without placing unsustainable demands on the environment.
Through its route structure, the MSc in Natural Resources allows students to study their choices of plant health and protection, environment and ecosystems, post harvest technology and, also, regulatory issues more intensively. The programme is evolving continuously, and attracts students from many developing countries (19 to date), as well as the EU. Students may follow the programme in taught or research modes and all students undertake a research project.
Course details are available on NRI’s website at: http://www.nri.org/study/study.htm. For further information, please contact Dr Peter Burt on Tel: 00 44 (0) 1634 883231 or e-mail: nri-training@gre.ac.uk.
Improved management of groundnut rosette disease in Uganda
For people in many developing countries, groundnut (Arachis hypogea L.) is an important subsistence crop that provides high levels of digestible protein and oil. In Uganda, the area planted to groundnut is increasing and farmers are able to enhance their income by selling some of their harvested crop for local markets. Yields remain low, however, averaging 560 kg ha-1 of dry seed. This compares with yields of 2500-3000 kg ha-1 that can be obtained using the best varieties and optimum management practices. One of the main constraints to groundnut production in Uganda is groundnut rosette disease. The disease is caused by a complex of viruses that are transmitted by aphids, Aphis craccivora, and it results in severe yield loss. Control of the disease is difficult and resource-poor farmers do not have access to suitable technologies.
|
We have been working with farmers and partner institutions in the 'Teso' district of eastern Uganda to develop and promote groundnut varieties with resistance to groundnut rosette. A large-scale household survey revealed that farmers considered several traits when selecting a groundnut variety. The most important features they looked for were high yield, pest and disease resistance, drought resistance, time to maturity and quality characteristics. These traits were all incorporated into breeding lines of groundnut developed at the Malawi station of the International Crops Research Institute for the Semi-Arid Tropics. The most promising lines were evaluated in a comprehensive series of on-station trials coordinated by Mr Charles Busolo-Bulafu, Head of the Oil Seeds Programme at the Serere Agricultural and Animal Production Research Institute (SAARI) in Uganda. At the same time, an extensive network of on-farm trials was conducted with the assistance of staff from the Department of Agricultural Extension and several non-government organisations (NGO). The work has been funded by the Department for International Development through its Crop Protection Programme.
Based on the results of the trials, which included an evaluation of the lines by farmers, two new groundnut-rosette resistant varieties were released in March 2002. Serenut 3R and Serenut 4T have distinctive qualities that conform to the requirements of different local markets. The varieties are both short duration types, allowing two crops to be grown in a single year and so greatly enhancing the income that farmers are able to earn from their land. In order to ensure that the varieties will be made widely available to smallholder farmers, a system for seed multiplication and transfer has been established. A local NGO, AT-Uganda, is working with SAARI to promote the farmer-to-farmer transfer of the new varieties. Early indications suggest that this approach is proving highly effective and that farmers are rapidly adopting the improved varieties. To support this initiative a new groundnut production manual has been produced that includes recommended practices for both pre- and post-harvest activities.
For further information, please contact Dr. Tim Chancellor; email t.c.b.chancellor@gre.ac.uk
Forecasting breeding opportunities for Quelea birds
Red-billed Quelea birds (Quelea quelea) are major pests of small-grain crops throughout sub-Saharan Africa. The DFID Crop Protection programme funded NRI research in conjunction with the University of Edinburgh and collaborators in southern Africa to improve control strategies against this pest. Hitherto, such planning has been difficult as quelea birds are abundant and breed colonially when conditions permit, migrating long distances, sometimes > 2000km, to seek appropriate breeding areas or to avoid food shortages.
A DNA-based study showed that birds ranging from the south of the Democratic Republic of the Congo to South Africa were all part of one interbreeding group, the southern subspecies Q. q. lathamii. Genetic mixing is facilitated as the birds move within their distributional area in response to the seasonal movements of rain-fronts. Rain causes their main food, grass seeds, to germinate at the start of the wet season forcing birds to move to areas where the seeds have yet to germinate. When rain reaches these areas, the birds are forced to move again, usually returning in “early-rains migrations” in the direction whence they came. By this time sufficient rain needs to have fallen to exceed another threshold within a restricted period for the new grass to have produced fresh seed. Breeding may then commence and be repeated elsewhere later. It is the young, newly fledged, birds that cause most damage to agriculture.
|
A model to predict where and when populations of the birds are likely to breed was produced. It relies on rainfall estimates derived from Cold Cloud Duration (CCD) data collected from the Meteosat satellite. During the model runs in 2001- 2002, each one quarter degree square (now improved to predict at one quarter degree square resolution) in southern Africa was allocated a colour according to one of four possible conditions.
The output maps were superimposed with information on squares where quelea had bred in the past (and hence the habitat was suitable) or where they had never been recorded at all (where the habitat is presumably inimical to them and marked with a cross). An example of the output is given in Figure 1, which shows the situation at the end of the week beginning 11 February 2002. At this time, new breeding colonies could have been established mainly in two separate eastern and western areas (red squares) on either side of where the zones had become unsuitable (brown squares). The pattern predicted during the course of the 2001-2002 season was broadly consistent with observed events, as 72% of breeding records were within squares predicted to be suitable and none were in white squares. In 2002, the model output was made available online at http://www-web.gre.ac.uk/directory/NRI/quel. It is hoped that the forecasts will help control teams in southern Africa to identify where and when crops are likely to be damaged and to target their operations against nesting colonies more effectively.
Some project publications
DALLIMER, M., JONES, P. J., PEMBERTON, J. M. & CHEKE R. A. (2003) Lack of genetic and plumage differentiation in the red-billed quelea Quelea quelea across a migratory divide in southern Africa. Molecular Ecology 12: (in press).
JONES, P. J., DALLIMER, M., CHEKE, R. A. & MUNDY, P. J. (2002) Are there two subspecies of Red-billed Quelea Quelea quelea in southern Africa? Ostrich 73: 36-42.
JONES, P. J., ELLIOTT, C. C. H. & CHEKE, R. A. (2002) Methods for ageing juvenile Red-billed Queleas Quelea quelea and their potential for the detection of juvenile dispersal patterns. Ostrich 73: 43-48.
Tick- and tsetse-borne diseases have a huge impact on the health and productivity of African livestock; tsetse-borne trypanosomiasis, for instance costs Africa some US$ 4.5 billion a year. Treating cattle with acaricides has long been an important means of controlling tick-borne diseases, and in recent years various pyrethroid-based formulations have become increasingly important. In the 1980s, it was realised that these formulations were also effective against tsetse and thus the use of pyrethroids to control tsetse and ticks simultaneously has proliferated.
|
For poorer livestock owners however, this technology is not only too expensive but also poses two serious risks. First, pyrethroids can kill the invertebrate fauna that play a crucial role in the natural process of breaking down cattle dung to be incorporated into the soil. Disrupting this natural source of fertiliser would be disastrous for many mixed crop-livestock farmers. Second, most indigenous breeds of cattle in Africa can develop a natural immunity to tick-borne diseases. This immunity depends on young animals being exposed to ticks and hence a reduction in the numbers of ticks attaching to cattle can lead, paradoxically, to an increase in tick-borne diseases. Scientists from NRI, supported by DFID's and FAO's Animal Health Programmes, are collaborating with various UK- and Africa-based scientists to understand the interactions between ticks, tsetse and cattle and hence develop practicable, ecologically-sustainable and cost-effective solutions.
Steve Torr and John Morton, in collaboration with Paul Coleman, John Hargrove (epidemiologists from the London School of Hygiene and Tropical Medicine and Johns Hopkins University), Mark Eisler and Noreen Machila (veterinarians from the Universities of Glasgow and Edinburgh), have been looking at various theoretical aspects of tick- and tsetse-borne diseases. Amongst other things, they have used simple analytical and simulation models to investigate how factors such as pathogen virulence, host immunity and livestock distribution affect the epidemiology of tick-borne diseases and the population dynamics of tsetse.
The models suggest that acquiring and maintaining immunity to tick-borne diseases depends essentially on maintaining tick populations above a certain minimum threshold. Hence, tsetse control measures need to reduce their impact on tick populations.
|
Research conducted in collaboration with Zimbabwean scientist Clement Mangwiro is suggesting a number of ways that this might be achieved. For instance, using a form of DNA fingerprinting to determine the individual-specific hosts of tsetse, we have shown that most tsetse feed only on the larger cattle within a herd. Moreover, observational studies of the feeding behaviour of tsetse have demonstrated that they feed largely on the lower legs of cattle whereas ticks attach to other regions such as the ears or udders. Thus by applying pyrethroids to, say, only the legs of older cattle might control tsetse but would leave tick populations. Such an approach is being assessed in collaboration with Glyn Vale in Zimbabwe and preliminary results suggest that selective application of pyrethroids to the legs of adult cattle reduces insecticide costs by 95% with little reduction in efficacy against tsetse. Currently, research is assessing the effects on tick species.
Glyn Vale has also been working with Ian Grant to look at the environmental impact of pyrethroids. Their research has shown that veterinary pyrethroids kill beneficial insects and results from population models suggest that the levels of mortality associated with pyrethroids pose a significant risk to slow-breeding species such as the beetle Heliocopris dilloni. However this environmental risk can be largely overcome by treating the legs of cattle which prevents the pyrethroid contaminating the dung. Thus it seems that the prospects of developing a cost-effective and sustainable method of controlling ticks and tsetse are good.
For further information, please contact Dr. Steve Torr, or email s.torr.@gre.ac.uk
Begomovirus disease management for sustainable production of tomato in the Caribbean
|
A European Commission Framework 5 project in collaboration with colleagues in France (Centre International de Recherche Agronomique pour le Development and Institut National de la Recherche Agronomique), Cuba (Centro Nacional de Sanidad Agropecuaria and Instituto de Investigaciones Horticulturas Liliana Dimitrova), Dominican Republic (Instituto Superior de Agricultura) and Trinidad (University of the West Indies) is making progress towards understanding the key factors affecting the incidence of whitefly-transmitted viruses of tomato in the Caribbean. NRI's role is to lead the epidemiological component of the project and also to contribute to the evaluation of IPM packages based on crop management and resistant varieties. The project web site is http://betocarib.cirad.fr.
In the first year of the epidemiological work, a survey of 84 tomato fields in Basse Terre, Guadeloupe has shown that the quality of general crop husbandry practices (weeding, irrigation and plant quality) was associated with lower disease incidence (General Linear Model, P=0.003). The survey has raised an interesting question that can now be investigated experimentally. This may lead to much needed new control alternatives for begomovirus disease problems in the Caribbean.
For further information, please contact Dr. John Holt (lead investigator) or Dr. Tim Chancellor, or email: j.holt@gre.ac.uk or t.c.b.chancellor@gre.ac.uk
Wet/dry crop rotation reduces malaria incidence in southwestern China
Malaria used to be a major problem in Sichuan Province in southwestern China until the introduction of insecticide- treated bednets during the period 1987-1990 dramatically reduced the incidence of the disease. Since then, however, a significant further reduction in the incidence of malaria has been achieved. Dr Kang Wanmin, of the Sichuan Institute of Parasitological Diseases in Chengdu, attributes this to the introduction of new agricultural practices in the Province.
Previously, it was only possible to grow one crop of rice in Sichuan, due to the relatively cold climate. Water was retained in fallow paddy fields throughout the winter for use in the spring-planted crop. These flooded fields were ideal breeding sites for malaria vectors and very high densities of mosquitoes were present from May until August. With the introduction of new reservoirs and irrigation systems, farmers are now able to grow a second crop of wheat or vegetables. Since these crops do not require standing water in the field, conditions are not favourable for the survival of mosquitoes after the rice has been harvested. This has reduced the potential for large populations to develop during the peak transmission period. Mosquito numbers in the rice crop are further reduced by periodically allowing fields to dry out before flooding them again with irrigation water. This practice does not reduce grain yields, provided fields are not allowed to remain dry for too long.
The new crop management systems were first introduced in 1990 and now cover an area of more than 2 million hectares. This represents about 75% of the total area of rice production in Sichuan Province. Gabriella Gibson has been working with Dr Kang and his colleagues to help them evaluate the data they have collected during the past few years. She has also been examining the possible implications of the Sichuan experience for similar agroclimatic zones in Eurasia. In southeastern Turkey, for example, where new irrigation schemes are being developed, there have been several epidemics in recent years. This area still contains endemic foci of malaria. As fieldworkers frequently sleep outdoors near the fields in the hot malaria season they are at high risk of being bitten. The lessons learned from Dr Kang and his team may help to reduce the malaria problem in Turkey.
For further information, please contact Dr. Gabriella Gibson; e-mail: g.gibson@gre.ac.uk
Five students have successfully defended their PhD theses since the start of this year. Congratulations to Titus Alacai (Uganda), Liezel Herselman (South Africa), Christopher Omongo (Uganda), Adam Prior (UK), Jeroen Willekens (Belgium). We wish them all the best for the future and look forward to continuing collaboration.
NRI has excellent facilities for a wide range of research disciplines and also benefits from access to the facilities of the new Science School at the University of Greenwich's Medway Campus. PAHH staff supervise a significant proportion of NRI's PhD students and many of these students are able to link their research to specific NRI-led projects. This provides useful opportunities to overseas students to gain expertise in topics that are of importance to their respective countries. For further information on research degree programmes at NRI please see our website at http://www.nri.org/study/study.htm.
About the Plant, Animal and Human Health Group of the Natural Resources Institute
Or contact the group leader, Tim Chancellor: T.C.B.Chancellor@gre.ac.uk