A comprehensive review of the major investigations on the biology and ecology of ticks of Africa reported in scientific journals in the decade 1980–1989 is undertaken. While there have been remarkable advances within the decade on research on feeding habits and patterns of ticks as well as diurnal and seasonal activities, many important areas of research were neglected. These include tick embryogenesis, development and survival under natural conditions, tick modelling, the phenomenon of host's natural resistance to tick infestation, pheromone and biochemical studies and field sampling of ticks. The review also shows that laboratory studies on tick biological systems are scanty in East Africa and the need for greater tick ecological research in West Africa is stressed.

The review shows that in the decade 1980–1989, exotic Bos taurus breeds were predominantly used for experimentation on African ticks and the need to change focus to indigenous B. indicus cattle breeds for experimentation is highlighted. Attention is also drawn to the importance of researchers on African ticks to undertake long term sustainable research with clearly defined goals which can have quantifiable impact on tick control in Africa.

Selected studies in chemical ecology are described that have led to the identification of semiochemicals playing key roles in pest behaviour. In some instances, these compounds can provide alternatives to insecticides, but novel integrated control programmes including use of semiochemicals are described which have greater potential for the future. Thus, semiochemicals can be used to increase the efficacy of entomophagous fungi and to manipulate populations of beneficial insects. New strategies are being developed which use both antifeedant and attractant semiochemicals to deter insects from crops and aggregate them in areas where they can be destroyed. For the long term, strategies are described that employ genetic manipulation of crop plants so that pests are controlled by semiochemicals produced directly in the plants.

Different modes of immune reactions of insect vectors of human and animal diseases to nematode and protozoan parasites, fungi, bacteria, viruses and to other biological materials e.g. xenografts are discussed in this paper. Since most of the insect vectors of diseases are adult dipterans with low numbers of circulating haemocytes, their mode of defence against metazoan parasites and fungal pathogens is primarily by means of humoral encapsulation, with little haemocyte participation. Although earlier workers reported that humoral capsules in dipterans were formed without direct participation by haemocytes, this paper reveals increasing evidence of cellular involvement in the formation of humoral capsules, both at the initial and terminal stages of the encapsulation process. The role of phenoloxidase system in non-self recognition and in the process of melanization of haemolymph and capsules formed around parasites and fungal pathogens is also discussed. Immune defence of insect vectors against bacterial invasion by means of haemocytic reactions e.g. phagocytosis and nodule formation and by synthesis and release of humoral antibacterial factors e.g. lysozyme, attacins and cecropins is described and compared with similar reactions reported to occur in other insects. The role of lectins in defence of insect vectors against the parasites they transmit e.g. sandflies against Leishmania, blackflies against Onchocerca and tsetse against Trypanosomes is discussed and the possible mechanisms by which some parasites evade recognition and attack by the vector immune systems are also briefly discussed.

This paper is based on experiences obtained during a joint enterprise between the Social Science Interface Research Unit, of the Crop Pests Research Programme, and the Livestock Ticks Research Programme at ICIPE. Topics bearing on technology design and development are emphasized.

The resource-poor farmer as conceptualized within ICIPE and reinforced by research experience, is by definition a person who operates a diversified system of production in which food security concerns and cash income intakes are crucial.

The family/household provides most of the labour required in production in African farming communities. For this reason, their labour investment into the adoption of novel activities or technological innovation and their assessment of the value of such innovations requiring changes in their normative practice, is appraised primarily in terms of the returns they would get for the additional labour input.

It is noteworthy that much of the so-called family labour is, in fact, female labour. It is therefore arguable that the perception of the women of technological inputs and innovations as profitable, is crucial for the successful adoption and social acceptance of novel technology.

Although agricultural land is in increasingly short supply, it would appear that the crucial limiting factor in production is not a shortage of land per se, since a good number of households do not fully exploit all the agricultural land at their disposal. Labour, and/or cash income to secure additional labour, appears to be the most important constraint to production. This tends to suggest that for future technological interventions in agricultural systems of the rural poor, consideration will have to be given to inputs which optimize the use of family/household labour.

The escalating population growth suggests that focus on women's health and incomes could significantly and qualitatively improve the prospects for the adoption of new and improved technology in areas such as pest and vector control.

Crop Protection Training Department activities contribute to one of the primary objectives of the Permanent Interstate Committee Against Drought in the Sahel (CILSS), that is, agricultural self-sufficiency. Thus, since 1982, the Crop Protection Training Department has been in charge of implementing this objective, by the increased protection of crops and agricultural products against pests, diseases, and noxious weeds, using methods which can readily be incorporated into traditional farming practices.

Training courses are variable in length, and are designed for persons in middle to high positions, who will be able to immediately apply and use the training. The training course for Technicians in Crop Protection is the longest, lasting 2 years, and may be taken by those having achieved the level of Technical Agent in Agriculture. Shorter courses (4 months), are aimed at the more highly trained, particularly crop protection instructors at schools of agriculture, who can disseminate the information to the various participating states, and who can train high-level technicians and agricultural engineers to assist and educate the local farmers more efficiently. Short courses of 3 weeks are organized by member states to address specific problems (i.e. locusts, borers) or to counter an organizational problem (i.e. phytosanitary control). Training courses generally do not directly involve local peasant farmers, but do so indirectly through the mediation of trained personnel.

As regards dissemination of information on plant protection these are the same categories of personnel who are in contact with the research workers in the Sahel.

As a background to an IPM project, this paper describes pesticide treatment of cotton in Sudan Gezira, starting in 1945/46. Until the end of the 1950's, one treatment per season was sufficient to control the only important pest, the jassid, Empoasca lybica, but the number of treatments increased during the 1960's (from 3 to 5) and has since the early 1970's been 6–9.

The continuous use of pesticides has resulted in changes of the pest complex, ultimately creating “hyper” pests such as the whitefly (Bemisia tabaci), cotton bollworm (Heliothis armigera) and aphids (Aphis gossypii). The increase in number of applications of pesticide is coupled with the rising costs of pest control and a stagnant yield. The stickiness problem created by the honey dew of whitefly and aphids increased with the rising number of sprays. The exclusive use of chemical control not only failed to improve the quality or quantity of the yield, but put a great strain on the national economy as well.

The Sudan therefore requested the FAO to initiate an IPM project starting in 1979, with financial support from the Netherlands. During the past 2 years support has also been given by the World Bank. The IPM approach has given very valuable results during the last two seasons when large (more than 100 acres) plots in the Gezira and Rahad Schemes were left unsprayed with the objective of investigating the potential of the natural enemies in the absence of pesticides, and to compare findings with population trends of pest and beneficial organisms in the fields subjected to conventional chemical control.

The first significant finding was that Bemisia tabaci and Aphis gossypii can be managed at desirable levels by their indigenous natural enemies, and that their outbreaks are attributed to the decimation of these natural enemies by chemical treatment. Populations of beneficial arthropods were consistently much lower in the fields which received regular pesticide applications.

The result of the large-scale experiments indicate that Empoasca lybica is the only really damaging pest (“key pest”) in the Gezira because of the absence of natural enemies to regulate its population. Control of E. lybica in the 1940's and 1950's resulted in the creation of Heliothis armigera as a major pest. This situation necessitated early season applications of pesticides to suppress H. armigera, which further reduced the role of the natural enemies of B. tabaci and A. gossypii. Both have developed into major pests of regular occurrence.

Cotton farmers in Gezira are now faced with a complex of very serious pests. In order to solve this problem, we will have to make drastic changes in pest control strategies and to adopt an IPM approach as soon as possible. The biological control H. armigera is considered as first priority in order to avoid the early season application of pesticides. Trichogramma pretiosum was introduced from the USA and released in the Rahad Scheme in 1988/89. The preliminary results are very promising.

Cultural and biological control of E. lybica will be attempted in order to further reduce pesticide applications. The control of this pest by the use of “milder” pesticides is also included in the programme.

The presently used threshold levels for all major pests are very low, and are under revision through properly conducted large-scale experiments.

FAO's role in integrated pest management (IPM) in Africa has many components. Broadly speaking, it is the promotion of IPM in member countries, done within the context of strengthening plant protection in general and under the guidance of the FAO/UNEP Panel of Experts on Integrated Pest Control.

Activity areas undertaken by FAO which have links with IPM, include:

Awareness, creation and promotion of IPM

Organizes meetings, seminars, workshops, etc. to discuss and present results obtained in field projects; participates in meetings organized by other organizations; prepares publications on IPM in general, or on specific components of IPM, and on results obtained in field projects; and prepares teaching and training materials on improved plant protection and IPM.

Infrastructure

Sets up or strengthens plant protection services or plant research institutes to make them functional, giving due consideration to regulatory functions; gives training in improved plant protection at all levels within the framework of the field programme.

Development

Develops appropriate pest control measures in line with the IPM strategy.

Implementation

Conducts field projects to strengthen capabilities in plant protection at the national level; conducts IPM implementation projects and plant production/protection projects.

Policy development

Convenes regular meetings of statutory bodies (various panel meetings); convenes meetings or expert consultations on special topics; advises member countries on strategies to increase capabilities in plant protection.

Co-ordination

Convenes donor meetings; co-ordinates donor activities and inputs; conducts regional or global activities on specific topics such as quarantine, pesticide residues, etc.

There are 43 identified insect pests of sugar-cane in Mauritius, of which several are important enough to warrant control measures. However, insecticides are not used for this purpose. All the insect pests of sugar-cane are controlled biologically. This includes traditional biological control using parasites or predators, as well as more recent biology-based methods like the use of resistant cane varieties, sex pheromones, etc.

Mauritius has the distinction of being the first country on record to have successfully introduced a natural enemy, namely the Minah bird, specifically to combat a pest—the Red Locust, Nomadacris septemfasciata, in 1792.

Very few of the insect pests in Mauritius are indigenous; most of them are exotic, having been accidentally introduced into the country, one way or the other. Some of the important ones include: spotted stem borer (Chilo sacchariphagus), armoured scale (Aulacaspis tegalensis), white grub (Clemora smithi), white grub (Heteronychus licas), soft scale (Pulvinaria iceyi), armyworm (Leucania loreyi) and pink borer (Sesamia calamistis).

The introduction of various natural enemies from different parts of the world has been made over the years with different degrees of success. In all, there are presently a total of 102 species of parasites and predators controlling 43 species of sugar-cane insect pests.

With sugar-cane spread out over most of the island and representing 90% of all cultivated land, close vigilance over the important pest populations, and swift counter measures as appropriate, is required. This task is being performed efficiently and successfully by the Mauritius Sugar Industry Research Institute.

There is a large knowledge base available worldwide for growing many crops according to the principles of integrated pest management (IPM). CIBA-GEIGY is active in much IPM related research. Several biological control projects are being carried out at present and include studies of Trichogramma minutum against the spruce budworm in Canada; Encarsia sp. against glasshouse white-flies in Spain; the fungus Beauveria brongniartii against cockchafers in fruit gardens and forests of Switzerland and Italy; and the protozoan (Nosema) preparations against the African desert locust. In cotton, CIBA-GEIGY is concentrating on testing pesticides for the selectivity of beneficial arthropods under practical field conditions.

Some of the most important pests in cotton, rice and vegetables are monitored regularly for the occurrence of resistance, and strategies are being developed to overcome it. A computer model has been developed for American cotton, which is now under practical evaluation and which should allow for appropriate treatment decisions based on plant phenology and regular pest scouting.

General recommendations are given as to the implementation of IPM programmes in cotton, which are based on methodologically sound monitoring of cotton arthropods, establishment of economic thresholds, use of selective compounds or the selective use of broad spectrum pesticides, rotation of pesticides of different chemical classes to avoid the build-up of resistance, and a strengthened search for biological control alternatives such as more potent strains of Bacillus thuringiensis.

Insect pests and plant diseases are among the main factors limiting bean production in Tanzania. A survey of methods of pest and disease management in small-scale bean production systems was carried out in Mgeta Division.

The results revealed that small-scale farmers are well informed of the major insect pests limiting bean production. The farmers know the type of damage caused by most insect species and the time of their occurrence. Although farmers are not aware of the pathogens affecting their crops, they can distinguish damage caused by insects from those due to diseases. Farmers are also aware that diseases are associated with environmental factors which influence disease development.

Farmers use both deliberate practices and incidental practices to manage insect pests and diseases.

The most frequently used deliberate practice is avoidance. Choice of growing season and date of planting are observed closely as a means of avoiding diseases. Although beans are cultivated in both growing seasons (September–December and February–May), the first season is the best for growing beans. Rains are not very heavy, but reliable and well distributed, and the season does not end up with low temperatures and high humidity which favour development of fungal diseases. Planting commences as soon as the rains start because early planted crops suffer less from pests. Farmers do not use purchased inputs in the form of fertilizer and pesticides. Larger insects are killed mechanically.

Incidental control takes place in the form of a number of cultural practices. Intercropping with maize, potatoes, cowpeas, pigeon peas, cassava or sorghum is normal and reduces the risk of crop failure. Terracing, where crop residues and weeds are buried under soil, reduces the amount of initial inoculum of certain pathogens. Farmers use a mixture of seeds of different cultivars deliberately, some high yielding and early maturing; and some late maturing, thus ensuring the farmer of food early in the season and beans as a cash crop later. Such variety mixtures appear to provide a buffer against pests and diseases.

A breeding strategy should be developed for variety mixtures instead of pure line varieties as the productivity of pure varieties in most cases is associated with the use of purchased inputs such as fertilizers and pesticides which are beyond the reach of small-scale farmers. Variety mixtures have a greater efficiency in using environmental resources, and are less affected by pests and diseases, and thus give higher yields than pure varieties.