Preliminary electrophysiological tests on certain tarsal and ovipositor sensilla of stem-borers, Chilo partellus and Eldana saccharina, show that the sensilla are innervated by mechano- and contact chemoreceptor cells. Tarsal receptors are sensitive to sucrose, whereas the ovipositor sensilla are not and responses of the ovipositor mechanoreceptor units can be related to the oviposition behaviour of the moths.

Polycultural farming is widely practised in East Africa and has the advantage of ensuring a steady supply of food for the family throughout seasons of adequate rainfall. The food crops interplanted are cereals, root and oil crops with at least one legume species. There is a large pest complex associated with the system, but the severity of attack has only been quantified for a few. Pest management is largely indirect relying on natural enemies, weather conditions and removal and destruction of damaged plants. Wood ash is probably the only direct control applied. Crop yield losses are on the average minimal. Among pest management strategies proposed for the future are: introduction and propagation of pest resistant high-yield crop varieties, compatibility between food crops interplanted, suitability of soil types for a given combination, augmentation of beneficial insects and the use of nematode-suppressor plants either as interplants or during crop rotation and fallowing.

The concept and practice of IPM has emerged over the past two decades or more. The primary impetus for its development has come from developed countries. IPM technology transfer to developing countries has followed the earlier pattern of the ‘green revolution’. The technology being proposed requires high energy inputs and an intensive infrastructure to support it. These conditions simply do not exist in most developing countries. IPM programs for developing countries must be based on their own socioeconomic situation rather than on simple technology transfer. Better understanding of cropping systems must be the keystone to development of IPM programs. Chemical control should play a secondary role. Cultural and bioligical control and plant resistance adapted to subsistence farming holds the greatest promise. Little attention has been given to the reciprocal feature of studies of traditional agriculture. These practices embrace a wealth of time-honoured ecological wisdom which if unravelled could provide useful leads for modern agriculture. The sequence of steps contributing to this process are proposed.

Use of synthetic organic chemical pesticides introduced after World War II has resulted in a number of health, environmental, and socioeconomic problems discussed here. Both developed and developing countries have been affected. The problems in the developing countries of the tropics came about largely because of an error in transfer of technology. Pesticide technology developed by and for use in the developed countries was exported to countries with cultures and social structures that were not prepared to absorb this technology. Integrated pest management (IPM), an approach that reduces pest damage to tolerable levels through a variety of techniques, including natural enemies, genetically resistant crops, environmental modifications, and, when necessary and appropriate, chemical pesticides, represents an important trend toward rational management of crop pests in the developing countries. However, simply exporting IPM ‘packages’ from developed to developing countries would also be an error in transfer of technology. Each situation must be evaluated individually under actual farming conditions, and the IPM program must be tailored for the particular group of intended beneficiaries. Some of the interrelated social, attitudinal and institutional factors that should be evaluated are discussed.

There are several stem-borer species recorded on important cereals such as rice, maize and sorghum as well as on grain legumes like cowpea. Those of considerable economic importance are: Chilo partellus, Sesamia infer ens, Sesamia eretica, Busseola fusca and Eldana saccharina on maize and sorghum; Sesamia infer ens. Chilo spp., Maliarpha separatella and Tryporyza incertulas on rice; and Maruca testu-lalis on cowpea.

Chemical control of insect pests will continue to be a major component of integrated pest management. However, control of tissue borers with insecticides is relatively more difficult than control of the insect pests feeding externally on foliage, shoots and stems. The foliar application of dust and spray formulation of most of the available insecticides has generally proved to be unsatisfactory as these cannot penetrate deep inside the tissues in sufficient quantities to kill the borers.

The recent advances in pest control technology, placing greater emphasis on use of various pest management components as well as insecticide selectively based on improved application methods has now made the control of stem-borers more effective and economical. Advantage can now be taken of the knowledge of the specific habits of the pests, period of peak activity of the most vulnerable stage and the economic thresholds for determining the appropriate time of application to control these pests. The development of new systemic insecticides and their granular formulation has further contributed towards the effective control of these borers. The recent research findings and recommendations for the control of cereal stem-borers are reviewed and discussed.

This paper reviews progress made in the identification of the sex pheromones of lepidop-terous stem-borers and the use of these pheromones in crop protection. These uses include population monitoring with pheromone traps and control by mass trapping and mating disruption, and case histories for Ostrinia nubilalis and Chilo suppressalis are considered in detail to illustrate the problems encountered in applying these techniques. The pheromone blend, trap design, trap siting and pest biology are important factors in any monitoring system, and so far little progress has been made in correlating pheromone trap catches with subsequent larval infestations and crop damage by stem-borers. Control by mass trapping using pheromone traps has been little explored and is thought unlikely to provide a satisfactory control technique for many stem-borers. Control by mating disruption has been more extensively examined with encouraging results. The main potential of this technique would seem to lie in controlling pests of rice, maize and sugar-cane grown under plantation conditions.

Control of cowpea insect pests has been almost entirely achieved through the use of chemicals by progressive farmers. However, the peasant farmer has traditionally tended to rely on chance and has often been unable to obtain yields that would be profitable. This paper examines the farmer's dilemma and the jrossibility of using host plant resistance (HPR) as an adjunct to other control methods in developing a sound integrated pest management of cowpea pests. The status of HPR in cowpea is reviewed with a view to identifying the areas where progress has been made with respect to the measurement and identification of resistance to formulate an effective integrated pest control program. The difficulties in achieving this are discussed in the light of our present data bank and the diversity of cowpea pests.

Graminaceous crops are attacked by lepidopterous stem-borers all over the world causing severe crop loss. Chemical control of stem-borers is difficult and biological control is preferable for peasant farming systems. The most important genera are Diatraea, Chilo, Eldana, Sesamia and Busseola. Their natural enemies include egg, larval and pupal parasites and predators. The parasites are cued by different stimuli, some to host plant, others to borer tunnels or frass. Biocontrol was first attempted against Diatraea spp. in the New World where D. saccharalis is now under fair control in several countries. In the Old World attempts have been made to control C. sacchariphagus and E. saccharina without much success. In East Africa releases of exotic parasites against B. fusca, S. calamistis, C. partellus and E. saccharina have not been very successful and further work is suggested. Leguminous crops suffer from attacks of lepidopterous pod-borers. The most damaging species are Etiella zinckenelia, Maruca testulalis, Cydia spp. and Lampides hoeticus. There are relatively few records of important parasites and fewer still of predators, however, large parts of the world are still unsurveyed for natural enemies. Successful control using introduced parasites has been reported from Canada against C. nigricana and Mauritius against E. zinckenelia and M. testulalis. There appears to be scope for introductions of Caribbean parasites into Africa.

Field surveys along the Lake Basin and the Coastal regions of Kenya were carried out to assess the natural incidence of pathogenic microorganisms associated with the legume pod-borer, Maruca testulalis Geyer on the cowpea crop. A regular sampling regime was maintained on plots planted with four varieties of cowpea: T VX 66–2H, Vita 3 (TVU 1190), Ex-Luanda and Nyar-Milambo. Larvae of M. testulalis were recovered from the flowers and pods of the crop, and subjected to routine laboratory disease diagnosis including: tissue examination, culture incubation, microscopy and pathogen identification. The main groups of pathogenic microorganisms found to act as natural mortality factors to M. testulalis larvae include: protozoa, bacteria, fungi and a virus. A higher level of disease incidence and diversity on M. testulalis larvae occurred in the lake basin region of Kenya than the coastal part.

The current status of the cereal stem-borer problem on various crops in The Gambia is discussed. Various control strategies that can be properly selected and integrated are identified. These strategies offer promise for an effective and more economical control of stem-borer infestations and their implementation, it is envisaged, would go a long way in reducing losses due to these pests. The implementation of these strategies would not, also, be free of constraints. These constraints are discussed and ways of solving them suggested.

This paper highlights the current status of knowledge of the ecology and control of the maize stalk-borer, Busseoia fusca (Fuller). Migration has been shown to be an important parameter in the proliferation of the pest. Control measures advocated to the farmers consists of a combination of stover disposal and the application of chemicals. Synthetic pheromones have a place in the integrated pest management of B. fusca in Zimbabwe. Since most of this information is based on work carried out in the commercial sector, future investigations will aim at defining the extent of B. fusca infestations and magnitude of losses in yields incurred in the communal areas.