Centre Technique de Agricole et ACPIU Integrating biological control host plant resistance and I of a Integrating biological control and host plant resistance Summary report and recommendations of a seminar Ethiopia, 9-14 October I995 Technical Centre for Agricultural and Rural Cooperation (ACP-EU) The Technical Centre for Agricultural and Rural Cooperation (CTA) was Convention between the African, Caribbean established in 1983 under the and Pacific (ACP) States and the European Union Member States. CTA's tasks are to develop and provide services that improve access to information for agricultural and rural development, and to strengthen the capacity of ACP countries to produce, acquire, exchange and utilise information in these areas. CTA's programmes are organised around three principal themes: strengthening facilities at ACP information centres, promoting contact and exchange of experience among CTA's partners and providing information on demand. CTA, 380, 6700 AJ Wageningen, The Netherlands The Institute of Agricultural Research Ethiopia The Institute of Agricultural Research, Ethiopia was established in February 1966 by order number 42/58. The sole objective in establishing IAR was to foster the generation and transfer of agricultural technologies and information aimed at modernising Ethiopian agriculture so as to raise its productivity and efficiency. The International Institute of Biological Control (IIBC) of CAB International Within CAB International Crop Protection Services, the International Institute of Biological Control undertakes research and provides services, training and information from its six stations in Tropical America, Europe, Africa and Asia. Material in this publication was reproduced as submitted and has not been subjected to peer review or rigorous editing by CTA. Responsibility for the information in this publication rests with the individual authors. CTA 1997 ISBN: 92 9081 1773 Design and production: Karin Luttik, Graphic Designer bno, Arnhem, The Netherlands Cover illustration: Predatory mite top right) and two prey items, a rust mite top left) and a spider mite (Panonychus bottom left). - by Marcel Dicke and Kostense, Department of Entomology, Wageningen Agricultural University, Wageningen, The Netherlands). Contents Abbreviations and acronyms Preface group Basic research needs for the further evaluation of biological control (BC) and host plant resistance (HPR) interaction mechanisms group 2 Protocols and procedures for the practical integration of biological control and host plant resistance at the research level 10 group Improving farmers’ perceptions of crop protection in Africa and integrating biological control and host plant resistance on farm 15 West and Central Africa Eastern Africa group report group report Southern Africa group report Cowpeas, Cotton, Coffee Cereals group report group report Summary written on the basis of seminar recommendations 17 20 22 25 27 29 Abbreviations and acronyms AGRHYMET ASARECA BC BYDV CGIAR CILSS CORAF EARRNET FAO GTZ HPR IAR IARC ICIPE ICRISAT IIBC IPGRI IRLCO-CSA NARS OAU PPRI PRAPACE SACCAR SPAAR Agro-hydrometeorologicalservice of CILSS Association for Strengthening Agricultural Research in Eastern and Central Africa Biological control Barley Yellow Dwarf Virus Centre for Agriculture and Biosciences International (United Kingdom) Consultative Group on International Agricultural Research permanent inter-Etats de lutte la sdcheresse dans le Confdrence des responsables de recherche agronomique africains East African Rootcrops Research Network Food and Agricultural Organisation of the United Nations Cooperation (Deutsche German Agency for fur Technische Zusammenarbeit) Host plant resistance Institute of Agricultural Research - Ethiopia International agricultural research centre International Centre for Insect Physiology International Crops Research Institute for the Arid Tropics Control (CABI) International Institute of International Plant Genetic Resources Institute International Red Locust Control Organisation for Central and Southern Africa National agricultural research system Natural Resources Institute (United Kingdom) Organisation of African Unity Plant Protection Research Institute (South Africa) Regional Programme for improvement of potatoes and sweet potatoes in Eastern and Central Africa Programme damdlioration de la pomme de terre en Afrique centrale et de Southern African Centre for Cooperation in Agricultural Research Special Program for African Agricultural Research Preface For farmers in low external input agricultural systems in developing countries, host plant resistance (HPR) and biological control (BC) are potentially effective methods of insect pest control. Both are generally inexpensive, durable, non-polluting and locally improvable, which makes them sustainable components of integrated pest management (IPM). However, the possibilities and advantages for integrating host plant resistance and biological control have not been fully explored. While the relationship between biological control and host plant resistance will be generally positive, in some conditions, the overall effect on pest population is less than the sum of the effect of each factor. In principle, therefore, the positive integration of HPR and BC can have two objectives: additive or synergistic reduction of pest densities and protection of durability. Together with the Institute of Agricultural Research (IAR), Ethiopia and the International Institute of Biological Control (IIBC), CTA organised an African regional seminar on Insect Pest Control for Smallholders: Integrating Biological Control and Host Plant Resistance from to 14 October in Addis Ababa, Ethiopia. countries and from four European countries, as well Scientists from as representatives from CAB International, CTA, FAO, ICIPE and ICRISAT attended the meeting. The objectives of the seminar were to promote contact and exchange of experience on issues relating to the development of pest control through integrated pest management, and to develop strategies to integrate HPR and BC. Plenary sessions at the seminar examined the following topics: IPM in complex African farming systems; breeding for host plant resistance in IPM; the role of genetic resources in IPM; biological control of insect pests in an IPM context; host plant-insect-parasitoid interactions. Short communications were presented in three regional and three commodity sections to prepare the working groups on the following themes: developing protocols for the integration of HPR and BC; identifying research needs to study the interactions of HPR and BC; improving farmers perceptions of HPR and BC in Africa. This summary report features the reports of the seminar’s working groups dealing with thematic, regional and crop-centred issues. It also contains a summary text, based upon the recommendations of the working groups. 7 Working group I Basic research needs for the further evaluation of biological control (BC) and host plant resistance (HPR) interaction mechanisms Introduction and aim The development of HPR and BC has taken place independently and separately. Nowadays there are efforts to combine these two technologies for control of specific insect pests. However, integration does not mean apriori synergistic or even additive interactions and may in fact be antagonistic whereby the combined effects of HPR and BC result in a worse pest control. There is a real need, therefore, to examine the effect of specific crop cultivars on biological control agents in order to promote the integration of these two disciplines. The aim of this working group was to identify the basic research needs to achieve this goal. Our approach was to develop a blueprint for research requirements that can be applied to individual crop systems. Method The first step is to recognise that agriculture takes place within a system where the crop, the pest, the pest’s natural enemies and the environment interact. Second, to identify the basic research needs for a particular system it is necessary to categorize: the host plant resistance and tritrophic interactions and biological control. (Figure 1). The pest can be categorized according to whether it causes: direct damage or is a vector. If it causes direct damage, then is it a sucker, chewer or borer. The resulting categories differ essentially in their type of interaction with the crop plant. The equivalent plant resistance characteristics are categorized under: antibiosis antixenosis 8 Integrating biological control and host plant resistance tolerance. other effects on the pest via direct plant effects on the natural enemy, i.e. tritrophic interactions. Thus, these categories differ essentially in their interaction with the pest and the natural enemy. 5. Biological control is categorised according to whether it is: natural or indigenous control including conservation classical biological control seasonal inoculative biological control including augmentation and inundative biological control. For each of these, the natural enemy is categorized whether it is a predator, a parasitoid or a pathogen. 6. After categorizing the relevant aspects of the tritrophic system under current knowledge about the effects of each of the consideration, one reviews relevant categories.This can be done according to whether a particular pest control mechanism is effective and if not why not. If the latter is not known, are there options available for improvement especially with respect to tritrophic aspects? 7. This procedure will reveal gaps in current knowledge and will in brainstorming about potential tritrophic interactions that may negatively influence individual pest control aspects. The result will be areas of tritrophic interactions to be studied so as to develop a more effective pest control. 8. The effects of all relevant elements in the system should preferably be evaluated in the universal nomenclature of population dynamics. With sufficient knowledge, a model can be developed to study which effects are most important for effective pest control. 9. Knowledge of the mechanism responsible for the observed effects is not a prerequisite when selecting existing cultivars, lines and landraces. However, knowledge of the mechanisms is important in a breeding programme, because this will enable it to take place in the absence of pest and natural enemy, up to some essential evaluating stages. This procedure was applied by the working group to the situation of controlling the stem borer in maize. From this short exercise it was concluded that basic research is needed in the following areas: What types of HPR are there and how effective are they? In classical BC, the parasitoid is established but remains to be evaluated whether it is effective. For this parasitoid, which is very short lived (2-3 days) and with a high mortality in a host tunnel it is very important that it selects the right herbivore species. The plant “SOS-signal” does not seem to be specific in the cultivar studied. Is this cultivar dependency? Although natural control of the stem borer in maize exists, it is not effective at present. Research is needed to identify why this is so. Inundative control with pathogens gave variable results. Potential causes include the time of application. Production technology needs improvement and the plants themselves may affect pathogen effectiveness. In conclusion, a 30 minute assessment of the system resulted in several areas that need investigations in order to improve control measures through a tritrophic approach. Working 1 Conclusion Research on the influence of crop plants on biological control agents has been limited to date. However, the few studies carried out have produced very interesting improvements in the effectiveness of insect pest control. Thus, such research using a tritrophic approach is highly warranted. What has been developed here is a methodology to identify such research needs in individual systems. Some of this research should take the form of long-term mechanistic studies of tritrophic interactions but not, however, exclusively so. Many opportunities exist for using existing knowledge and resources to improve the integration of HPR and BC within the farmer’s field. Figure 1 Categorizing pests, host plant resistance and tritrophic interactions and biological control 1 effect A A A I I enemy Pest Agricultural setting 9 10 Working group Protocols and procedures for the practical of biological control and host plant resistance at the research level Introduction The group divided its deliberations into three parts: an appraisal of the current situation regarding plant breeding for resistance and biological control listing of the perceived limitations of the current situation and suggestions for new protocols and procedures to alleviate the perceived limitations. appraisal of the current situation We divided the discussion into a consideration of host plant breeding for resistance within the CGIAR mandated crops and other crops: CGIAR mandated Others Small grains Grain legumes Cassava cotton Coffee Cocoa Fruit trees Nut trees Tobacco Sugar cane Tea Vegetables Yams Groundnuts Sweet potato Irish potato Rice Maize Within these two categories we considered activities on host plant resistance (HPR) and biological control (BC) separately. Working Group 2 Characteristics of host plant resistance research: CGIAR mandated crops The international agricultural research centres ((IARCs) are the main repositories globally for germ plasm. They have mandates to carry out primary screening and selection of germ plasm at a small number of sites. National agricultural research systems (NARS) and universities carry out germ plasm selection and screening in-country using mainly locally collected material (land races) augmented with germ plasm released by the IARCs. IARC take a regional or continental perspective of pest and disease problems in their breeding programmes. NARS take a local perspective of pest and disease problems. IARC and NARS interact mainly via crop-mandate networks (e.g. EARRNET and PRAPACE) which are run by the IARC. Limited resources are provided to the NAR through these mechanism. Most trials are carried out on-station, though some IARC (e.g. ICRISAT) are moving towards on-farm trials. Release of germ plasm is controlled by NARS following local screening. Several examples were given of IARC-sourced or otherwise 'foreign' germ plasm being unsuitable for local conditions. CGIAR mandated crops which have been successfully bred for resistance to insect pests and the varieties released: Crop Pest Rice several planthoppers and leafhoppers (stem borer) Chilo (stem borer) (gall midge) Contarinia (midge) Aphis craccivora (aphid) (bruchid beetle) (thrips) (thrips) (white fly) Sorghum Cowpea Cassava (adapted from and 1994) I2 Integrating biological control and host plant resistance Characteristics of host plant resistance research non-CGIAR mandated crops: IBPGR in Italy is a global centre for germ plasm storage. We were unable to determine whether this centre contained a comprehensive collection of all nonCGIAR mandated crops and whether it was a significant source of germ plasm for the NARS. NARS and private companies are the main centres for breeding. NARS are important centres for germ plasm preservation. With the exception of coffee (which has its own research network for Africa and is beginning to coordinate its germ plasm collections), there is a general lack of networking amongst breeders of these crops. Most of these are cash crops have their own separate national or regional research institutes supported by governments and industry. However, research programmes are more carried out from within NARS. There is virtually no breeding for resistance to insect pests or diseases going on within the NARS for vegetables (other than beans which are CGIAR mandated). This work is being carried out almost entirely by seed companies. In spite of decades of research in Africa, there are no examples of HPR offering a complete answer to pest control within a crop system. mandated crops which have been successfully bred for resistance to insect pests and the varieties released: Crop Pest Cotton Empoasca sp. (leafhopper) white fly nematodes (scale insects) Tobacco Sugar cane In addition to these, several disease-resistant varieties of coffee, cotton, cocoa, tobacco, cashew nuts and vegetables have been released. Characteristics of biological control research: CGIAR mandated and other crops While our discussion revealed clear distinctions between CGIAR mandated crops and others with regard to plant breeding approaches, we could perceive no such clear cut difference in the approach adopted for the two crop groups in terms of biological control. The following comments thus refer to the methods of control adopted in both crop groups. Working Group 2 There has been an historical emphasis on classical biological control of single introduced pests within a crop system. Most pests are indigenous. Insufficient attention has been paid to understanding the role of indigenous natural enemies in pest control. Nor has sufficient attention been paid to examining whole crop systems in relation to pest ecology. The discipline is not as institutionally structured as HPR. Thus, biological control as a discipline is being undertaken by many different groups within NARS, IARC and others (e.g. ICIPE, IIBC, GTZ and NRI). The only good historical example of the integration of HPR and BC, taking a system approach and considering seriously the role of indigenous natural enemies is cotton. However, IPM research on coffee is clearly addressing these issues now. In spite of decades of research in Africa, there are no examples of biological control offering a complete answer to pest control within a crop system. Limitations of the existing approaches to HPR and BC Poor or no link between BC and HPR research. Lack of coordination among NARS (especially on non-CGIAR mandated crops). Overemphasis on HPR breeding at the expense of To much control over breeding programmes in IARCs compared with NARS (research too “top down”). Too much emphasis on classical biological control as opposed to conservation of natural enemies and insufficient understanding of the role of indigenous natural enemies in pest ecology. Lack of an holistic approach to crop protection incorporating BC, HPR and other components. Under-resourcing of NARS. Lack of farmers participation in evaluating pest control options and Lack of appreciation of the need for linkage between HPR and BC amongst policy makers, donors and science administrators. Improvements to the system Sensitise donors and science managers to the issues of HPR and BC linkage and research programmes accordingly. the need to Develop strong linkages between HPR and BC at all levels of research and implementation, but most especially ensure that the relationship is appropriately defined at the most basic level of research. NARS and private companies are the main centres for breeding. Design programmes to evaluate systematically in all major agro-ecological zones small-scale the diversity and action of indigenous natural enemies cropping systems. Incorporate ecosystem-based pest population dynamics studies into resistance screening programmes through close collaboration between breeders and insect ecologists. 13 14 Integrating biological control and host p k n t resistance Develop pragmatic research protocols based upon ecological theory that allow the integration of HPR and BC while avoiding the temptation to indulge in excessively detailed and academic ecological studies. Involve NARS’ researchers, extension and farmers in the early stages of resistance screening, utilising as many sites as possible, to take into account knowledge of regional variations in pest and natural enemy pressures. Ensure closer involvement of NARS in IARC core programmes and in the operation of LARC commodity networks linked through the SPAAR framework for action groupings (SACCAR, ASARECA and Strengthen links between national programmes working on non-IARC mandated crops through the FFA groupings. Ensure adequate resources for HPR-BC linked programmes within NARS through closer and more effective linkages between IARCs and other relevant international organisations. Transfer funds from the IARC breeding programmes to the NARS to ensure a more equitable involvement of NARS in HPR-BC research. But at the same time ensure, through appropriate government action, that NARS are properly managed and provide an acceptable career path for scientists, including continued training, resource availability and remuneration. Increase both government and industry support for mandated crops; and Ensure the adequate development of inter-regional collaboration among researchers at all levels. 15 Working group Improve farmers’ perceptions of crop protection in Africa and integrate biological control and host plant resistance on farm Farmers include integrated pest management among their practices but they may not fully understand the science behind it. Hence there is a need for: farmer education; sharing of information between farmers and research scientists. Approach should be systems oriented We recognise that various technologies, at different stages of development, are available in the different NARS and IARCs. Constraints Lack of education in IPM practice for researchers, extensionists and farmers. Lack of support for IPM in national agricultural policies. Lack of public awareness of IPM. Inadequate coordination and collaboration among the different agencies involved in IPM development and extension. General recommendations to deal with above constraints 1. Sensitise governments and policy-makers to adopt IPM as part of national agricultural policy through: lobbyists such as agricultural ministries, the OAU scientific council and the relevant experts of FAO, and the World Bank etc. at both national and international levels. establish national IPM steering committees to develop strategies to sensitise policy-makers and the general public on IPM. 2. Develop and improve collaboration and coordination of IPM initiatives among different agencies to harmonise activities. 3. Provide an environment that will enable farmers to make some investment in IPM. 16 Integrating biological control and hostplant resistance Actions be taken 1. Recommend to universities and agricultural colleges to include a full IPM course in their curricula. 2. Recommend the training of extension staff in IPM approaches. 3. Develop and use appropriate IPM training methodologies for farmers. 17 West and Central Africa working group report Topics presented Maize and Prostephanus (Togo and Ghana) Rice and Stem borers (Senegal) Oil palm and minuta (Cameroon) Cotton and biocontrol (Togo and Cameroon) General presentations on biocontrol and host plant resistance (Niger and Discussions of Prostephanus truncatus on stored maize in and Ghana Generalaspects Important insect in both West and Central Africa First found in Togo and Ghana: some results now available. Chemicalcontrol: In Ghana it was indicated that chemical control has not been fully accepted by the farmers but on the other hand the use of deltamethrin and methyl in farmers situations and phosphine in storage facilities seem to have produced encouraging results in Togo. Biological control: The predator, nigrescens (Coleoptera: Histeridae) has been introduced in Togo. (Studies were also carried out in Ghana and Although studies are still going on in Ghana, some results have been obtained in Togo where 80% predation was recorded. With the encouraging results, it is hoped that I: nigrescenswould be reared and released for the control of I? truncatus in Togo. IPM and l?truncatus: Because of the results obtained in Togo, the author thought it would be logical to control truncatusin granaries with insecticides and reinfestation be prevented by releasing I: nigrescens in nature. Results from studies in Ghana might help in interpreting factors (biotic and abiotic) affecting population dynamic in the field and in developing and validating a pest computer simulation model of these dynamics. A systems model can also help explore interaction between management and environmental factors. Integrating biological control and hostplant resistance Question and answer session: Q. Could Togolese farmers afford the recommended insecticide? A. Yes, because they are obliged to sell their produce later for financial gains. Q. Why both chemical and biocontrol of I? truncatus in Togo? A. They are complementary. A. The Ghanaian speaker advised the participant from Burundi to undertake studies on I? truncatus although it was not yet a pest. Rice and Stem borers in Senegal The author advocated the use of a combination of tolerant varieties, chemical method and planting date to control Chilo spp. which are the major stem borers in rice in Senegal. He also suggested that with this approach one insecticide application could be saved. Dr. M’boob, however, was of the opinion that insecticide treatment was not necessary because rice has the advantage of producing tillers. He also cited the Ghana experience which has produced encouraging results so far. Compensatory tillering was not translated into yield. Biological control of on oil palm in Cameroon Currently, this leaf-mining beetle is being controlled with an insecticide called EVISET 50 EC Thiocyclam hydrogenoxalete using the swing fog. Chemical control observationshave revealed the presence of four ant species and the farmers have been advised to protect and encourage the multiplication of the natural enemies. Attempts at biocontrol on cotton (Togo and Cameroon) Classical biocontrol of bollworms on cotton has not produced encouraging results. However, mixtures of some formulated microbial agents (NPV and low dosages of some pyrethrinoids (deltamethrin at active and cyperimethrin at 4 gave very encouraging results in Togo. The staggered control (TSC) appears to be more adapted to the conditions prevailing in some countries in West Africa. It has been accepted that it has the potential of conserving many predators and parasitoids of bollworms, aphids and leaf-feeding insects which have been identified so far. Dr. M’boob was of the opinion that thresholds of pests should be established by taking into account the natural enemy complex and the growth formed part of the scouting component of TSC. Another participant wanted to know under what conditions the trials were performed on farmers’ plots. General presentations on biocontrol and host plant resistance (Niger and Sahelian Agriculture: In the Sahelian Zone, subsistence agriculture is more common and pests constitute a major set-back. Because farmers do not have adequate resources, the best option for them is IPM. The author suggested that farmers, technical assistants and researchers, both national and international, should be involved in developing technological packages. Regional reports:Westand Central experience: Subsistence and plantation agriculture are common in The best way of helping the farmer to produce more is to provide him with resistant crop varieties which should be enhanced by the use of natural enemies. During the discussion session one of the participants wanted to know why biocontrol should be used whereas HPR was already present. The presenter indicated that BC was introduced as a complementary measure. General Observations Following all the presentations, it was observed that BC is not new in the region. Examples include manihoti on cassava, on mango on stored maize are worth mentioning. and It is worthwhile to note that all the main crop protection methods have been applied (chemical HPR and biocontrol). Biological control of the pests indicated earlier has been achieved through the introduction of either parasitoids or predators. Collaboration has been lacking in some of these biocontrol examples, the case of Ghana and Togo on is worth mentioning. Recommendations Mindful of the fact a number of pest have been introduced into the West and Central African sub-region, it is necessary for the member states to strengthen their respective quarantine services. Harmonisation of different research activities is necessary because it would help to redefine the roles of various national and international institutions. In future work emphasis should be laid on HPR and a thorough understanding of the conditions prevailing in farmers' fields. Funding is a very vital aspect and this should be taken into account all the time. 19 20 Eastern Africa working group report D.M. There were 5 presentations. Four countries (Ethiopia, Kenya, Uganda and Tanzania) were represented in this group. The papers described the history and current status of biocontrol and host plant resistance in the larger grain borer and water hyacinth. Observations The group discussed all presentations together and came up with the following observations: There existed past experience on classical biocontol and notable successes had by been recorded. For example Kenya There was currently limited biological control going on in the region though this has not been incorporated into government policies. Information on native natural enemies was found to be inadequate and, where it exists, it is not incorporated into biocontrol method. There was bias towards parasitoid as compared to predators and pathogens. There were variations in pest situations and status in different countries. There was inadequate information on the inter-relationship between pest, host, natural enemies, management practices and environment. Emphasis has been laid on high level resistance as opposed to partial resistance and tolerance of the crop. Recommendations There is need to quantify pests status so that they could be ranked in importance. There was need to identify the natural enemy complex and especially predators and pathogens. There is need to search for natural enemies of exotic pests in habitats where the pests originated. There was need to establish taxonomic expertise in the region. There was need to search for partial resistance or tolerance which could be combined with biocontrol. There was need to study between natural enemy, crop-cultural practices and environment. There was need to incorporate other control methods including the cultural, mechanical and even chemical in an IPM programme. The importance of indigenous knowledge on pests and control practices was advocated. Regional reports: Eastern There was need for training for researchers, extensionists, farmers and makers. There was need for a systems approach to IPM where the total pest complex is addressed, There was need for collaboration between disciplines, countries and even regions particularly in addressing pests which have a common occurrence like the larger grain borer, water hyacinth, striga, conifer aphids and migratory pests (locusts and army worms). There was need for funding to be able to carry out the activities outlined for the improvement of small-scale production. 21 22 Southern Africa working group report Kutywayo There were 5 presentations, one each from South Africa, Botswana, Malawi, Zambia and Zimbabwe. South Africa The presentation focused on available biological control programmes and cases where host plant resistance was being utilised. Prof. Nitzsche asked which plant pathologists and breeders were involved in developing the cultivars. Dr. van Rensburg replied that there was cooperation between the Plant Protection Research Institute (PPRI) and the breeders. Mr. Mingochi asked what methods were being used for diamond back moth in view of the problems of insecticide resistance experienced elsewhere. Dr. van Rensburg said there were no cases of insecticide resistance reported so far in South Africa because spraying is done occasionally and in most cases the pest is kept under natural control by parasitoids. Botswana Dr. Munthali gave an overview of the pest problems in Botswana before giving his paper on susceptibility of cassava cultivars to Bemisia and He evaluated resistance with reference to developmental period and relative growth rates. The varieties 1 were the most resistant while T21 was not the most susceptible. Dr. Dicke commented that it would have been better to use the intrinsic as indicator to avoid having to use two indicators. Q. Prof. Nitzsche asked how long the varieties had been on the market and suggested that this type of work should be done long before the varieties have been released. A. The land races have been grown for a long time in Malawi. reports: Southern Dr. Thindwa related the status of Biological Control and Host Plant Resistance in Malawi. She noted that little work was being done on both aspects at the national level. Zambia Mr. Mingochi mentioned red spider mites, diamond back moth and potato tuber moth as being important pest in vegetables and citrus white fly. Q. Prof. Nitzsche asked why the Bacillus tburingiensis gene was not being incorporated into solanaceous crops. A. Mr. Mingochi said this could have potential problems with farmers refusing to accept transgenic plants. Dr. Hill mentioned that Bacillus was specific to chewing insects and therefore could not solve the problem of sucking insect pests. He also disclosed that most African counties had not developed protocols for dealing with transgenic plants. Zimbabwe A presentation on the potential of biological control of important insects pests of coffee was given. It was noted that leaf miner, white borer, were the most important pests. bug and giant Dr. van Rensburg said that in Africa white borer infestations were associated with stressed plants. Mr. Kutywayo agreed and explained that the recent drought of 1992 had stressed the trees hence the rise in white borer populations. Q. Dr. Munthali asked if termites were also a problem on coffee in Zimbabwe as was the case in Malawi. A. Termites were a secondary problem where coffee had been attacked by white stem borer in the smallholder sector. The list of main pests in the region was drawn up and summarised together with ongoing projects on Host Plant Resistance and Biological Control. The sweet potato weevil was considered to be an important pest in the region. Non-specific pests such as storage pests, termites and migratory pest were common to all countries of the region. 23 24 Integrating biological control and host plant resistance Recommendations There was a need to set up collaborative on: Biosystmatics Phytosanitary Services Information Exchange Training (Biological Control and Evaluation of IPM) Strengthening of regional programmes of migratory pests e.g. IRLCO-CSA Collaborative regional research on IPM and Biological Control in conjunction with appropriate international centres such as IIBC Long-term partnerships between NARS, universities and other research centres to be encouraged e.g. partnership on stalk borers in cereals Regional projects to address common problems such as vegetable pests should be initiated. 25 Cowpea, cotton, coffee working group report Three papers were presented covering coffee, cotton and cowpea. They outlined the major pests and methods currently used to control them. Coffee Pests Control Options Coffee berry borer - Hypothenemus hampei Ferrari Antestia - Antestiopsis spp Leaf miner - Leucoptera spp L. and L. caffeine Coffee Scale Coccus Aspidiotus sp. patterson kenyae insects Host plant resistance Cultural methods D' vastatrix van Hall Cotton Control options Pests Major pest is armigera Other major pests - sucking pests 22% (white fly, aphids, sucking bugs) yield loss HPR Resistance to jassids Okra-leaved varieties resistant to white fly Cultural methods Trap crops for H. armigera tasseling maize groundnuts Distribution of trash H. armigera Early planting - aphids Chemicals Main control measure for armigera; white and spider mites are probably induced pests 26 Integrating biological control and hostplant resistance Cowpea Control options Pests Aphids -Aphis craccivora Pod bugs (Thrips) HPR Single gene (Aphids) Natural enemies Parasitoids predators and pathogen Aphid problem in irrigated cowpea but less than in inter-cropped situations Observations and recommendations High resistance sometimes not durable, may also be antagonistic to natural enemies. Host plant resistance programmes should consider a wide spectrum of pests. Pesticide use may be unavoidable in the short term. However, consideration should be given to compatibility with IPM. IPM issues in larger-scale agriculture should not be neglected. There is need to consider the pest situation in other crops such as groundnut, beans and chick peas which were not covered by crop working groups. 27 Cereals group report Presentation covered activities on biological control, host plant resistance and botanical control of insect pests. Although many crops are grown in Eastern Africa, in the group discussion we gave priority to maize, sorghum and wheat. Below is a brief report on pest problem, past and present status of biological control and host plant various resistance studies, future prospect and various constraints encountered activities crop by crop. Wheat Wheat is one of the major cereal crop grown in Africa. Its productivity, however, is affected by several production constraints among which insect pests are the most important. They cause considerable damage and losses. The most important insect pests attacking wheat crop are various aphid species, including Russian wheat aphid, the green bug, the red-chemy-oat aphid, maize aphid and other species. Aphid also transmit important virus diseases such as BYDV. Termites, bush crickets, chafer grubs, army worm and locust are also considered a major pest in the region. Several attempts have been made to establish a classical biological control (i.e. using parasitoids) for the control of Russian wheat aphid in South Africa. The occurrence of natural, indigenous control have been also reported in the region. Work on the development of plant resistance is still going on in South Africa and the Sudan. However, so far, there has been no tangible and recommended biological control and HPR for this crop. The work on other pests is still very limited in the region. Collaboration between disciplines is suggested for the development HPR and biological control strategies. Integration of host plant resistance (HPR), biological control and other possible control strategies should be taken into account for the development of IPM system. Several constraints could be mentioned but the most important ones are: Resistance in most pest problems does not last for a long time because of the development of virulent biotypes. An examples being the case of graminum biotypes in Sudan. To overcome this problem strategies of variety mixing, gene pyramiding and gene rotation is suggested by the group. However, we have to consider the effect on the host plant of the natural enemies while employing these methods. The wheat programme should concern itself with aphids but also indirectly with disease transition (BYDV). 28 biological control and host plant resistance Maize and sorghum The major pests of maize and sorghum are listed below: Field Pest Stem borers, Head bugs, Aphids, Midges, Shoot fly, Termite, Cricket, Bollworm, Army worm, Grass hoppers and Locust. Storage Pest Several storage pests have been listed but the most important one are larger grain borer weevils and various moths. Status of biological control and host plant resistance Considerable effort has been made to use classical biological pathogens and HPR on stem borers. But success has been very limited so far. Biotechnical work is in progress to solve borer problems. Prospects Developments of single technology solutions are negligible in the region. Solution should also come from integration and interaction of HPR and biological control and other control strategies within the IPM context. Development and use of bio-pesticides and botanical control should be considered as alternatives. Breeding in tritrophic context should be considered. New association in classical biological control should also be practised. Constraints Lack of early awareness of pest problems. Genetic diversity and plasticity over the existing pest population. Lack of interdisciplinary approach in pest management system. Lack of funding to find novel methods of pest management systems and to train researchers, extension agents and farmers. 29 written on the basis of seminar recommendations The idea that the effects of parasites and predators in regulating insect pest populations can be modified by the plant itself is relatively old. Rabb and Bradley, for instance, wrote on the influence of the host plant on the parasitism of eggs of the tobacco horn worm, as early as 1968. Much work has been carried out in this field, as can be seen from the book by Boethel and Eikenbary (1968) on the interactions of plant resistance and parasitoids - predators of phytophagous insects, and the more recent (1994) update by Thomas and Waage on the same subject. Despite changes in research that increasingly favours the integration of plant protection methods (cropping methods, varietal selection and breeding, controls, etc.), using different types of integrated management of the plant health risks, there can be no denying that as far as development-oriented research in plant protection is concerned, "breeders have tried to create varieties that are resistant to certain insects while the entomologists are concentrating on bio-controls using predator and parasitic species." (Spore, May-June 1996). Building on this observation, the organisers of the seminar CTA held in Addis Ababa from 9 to 14 October 1995 on Integrated Pest Control on Small Agricultural Holdings: Integration of Biological Control and Varietal Resistance recommended making the participants from sub-Saharan African countries more aware of this original approach. The input from numerous representatives of the world of plant protection have made it possible to hold a round table, in order to hear from, or sound out, the other countries and assess the state of the art in the field. - West and Central (Presentation of papers grouped according to Africa, East Africa, Southern Africa, or per cultivated plant such as cowpea, cereals, or cassava). There were also productive discussions organised as part of these work groups (Spore, December 1995). A review of the presentations concurs with the statement made above concerning the ever-growing separation between varietal breeding and biological control. A systematic look at the problem of pest and plants in the region shows that, depending on the case, preference was given either to varietal selection or to biological control. Entomologists are especially up to date on progress in biological controls since they have been following research conducted on pests accidentally brought in from other continents or regions: the green acarians, the cassava bug, the larger grain borer, fruit tree bugs, the Russian "puceron" and the aleurodes. 30 Integrating biological control and host plant resistance Chemical methods and farming techniques play an important role as far as the endemic pests that periodically swarm are concerned. Varietal selection is constantly being used through campaigns to identify resistant cultivars and through varietal deletion per se. In certain cases the problem was solved by adopting one of the two methods. But in many other cases, the problem was only partly solved or not solved at all. In situations marked by total failure, the participants recognised that the integrated approach, which had been largely neglected, should now be adopted. Since the situations encountered by plant protection specialists in the field are very varied, it would be irresponsible to proclaim integrated control measures as the solution to all the problems: the participants were extremely clear on this question. But the presentations and the ensuing discussions seen from the angle of integrated biological control methods, and varietal selection, increased awareness of the originality of this approach and prompted all the groups to make recommendations along these lines. This preliminary awareness effort was useful in developing a constructive approach to the work done by the different groups: Need for research to study the mechanism that govern the interaction between varietal resistance and biological control (Group 1); Protocols and methods for integrating the two approaches in research (Group 2); Sensitisation farmers to this approach, and their contribution (Group 3). Group 1: The concept of varietal integration covers many complex situations stemming from the diversity of plant matter to that of parasite relations and the variability of the ecological situations in which the tritrophic system develops. This integration is not systematically beneficial, and all types of cases may have to be faced, which explains the extreme importance of prior knowledge about the organisms on the site and the interaction between them. Research in this field should not be organised as the juxtaposition of approaches based on genetics and on bio-control; it needs to be more specific and be conducted as an investigation designed to understand the relations between the plant and its genetic diversity, the plant eaters, the parasites-predators, all the while recognising that the plant has significant influences, either directly or indirectly, on the auxiliary parts, and vice versa. The group strove to develop a methodology to identify the knowledge needed for this approach as far as the organisms which are to be found; the relationship between the plant and the phytophagous elements; and between the latter and the auxiliary parts and plant resistance. Also how tritophic influences work. This procedure proved appropriate for elucidating past knowledge and, further, the fields that require investigation. Joint efforts using a tangible model, regardless of system, brought out the needs and diversity of integrated research and conceptual unity. Summary Group 2: This work group started by reviewing the current situation and work done previously by both the national (NARCs) and the international (IARCs) agricultural research centres. The review generally showed that the integrated holistic approach had seldom been used for the various components of plant protection work and in particular how rarely efforts had been made to integrate bio-controls and varietal selection. Too much is being done on varietal improvement alone (especially at the IARCs) or on traditional biological control work without giving heed to local auxiliaries and studying their environment. These observations led to recommendations that fall in two fields: one concerns the scientific methods and protocols for integrating the two approaches, and the other concerns the strategy to be developed in order to promote this integrating approach. The scientific level involves promoting applied research to ensure the integration of varietal resistance and bio-controls, ensuring the participation of geneticists and ecologists specialised in population dynamics, devoting research to biology and ecology and to the various activities of the local auxiliaries at the eco-regional level. Operational type recommendations mainly refer to the relation between the IARCs and the NARCs and to ways and means of maximising cooperation through a) programmes that are defined jointly with effective participation of scientists and representatives from the national centres, in various ways and taking into account local level knowledge and experience, and b) joint efforts to obtain funding for this type of approach either as part of the IARC budget or through international funding agencies. Group 3: Using integrated management comes naturally to the African farmer, but he does not perceive the significance from a methodological point of view. This explains the importance of training the farmers, and maintaining constant contact with technical services and with scientists. At another level of responsibility, an unfortunate absence of a markedly integrated protection-oriented policy has led to inadequate public information, and inadequate resources and coordination within the technical services and with scientists. Governments and politicians must be made keenly aware of the need to promote integrated plant protection. Similar awareness should be created at the international level among selected agencies and at the national level in ad hoc committees. This would make it possible to improve the mechanisms involved in joint activities, coordination, training and sensitisation and, thereby, improve the farmer's uptake of the integrated approach to plant protection. 31 32 biological control and host plant resistance References Anonyme, 1995. Interactions entre la plante Spore, ennemis dans la lutte Anonyme, 1996. Plantes et Spore, les insectes ravageurs et leurs pour la protection des cultures, Boethel, D.J. and R.D. Eikenbary, 1986. Interactions of plant resistance and parasitoids and predators of insects, Wiley and Sons, Chichester, England. Rabb, R.L. J.R. Bradley, 1968. The influence of host plants on of the tobacco horn worm. Journal 61: eggs Thomas, M.B. J.K. 1994. Integration of biological control and host plant resistance breeding, a scientific review. CTA, Wageningen, 99 pp.