INTEGRATION OF ENTOMOLOGICAL RESEARCH IN HORTICULTURAL INVESTIGATIONS IN EAST AFRICA

A joint approach to the investigation of scientific problems in developing countries is the type of research offering the best opportunities for crop improvement and food production but this approach has yet to find its place in East African horticultural science. The loss of quality and value in horticultural crops due to pest injury and the presence of chemical residues at harvest or marketing is often great and problems of this nature call for the active participation of the entomologist in horticultural investigations.

Horticultural research in East Africa has not been matched by entomological investigations on the control of important pests on horticultural crops. Of the 48 topics discussed at the Specialist Entomological and Insecticide Committee (1969), only two papers were directly devoted to insect problems on horticultural crops: 'The Control of Onion Thrips (Thripstabaci)' and 'Insect Pests on Beans'.

Although horticultural crops, with the exception of coffee and tea, are still considered as minor crops in East Africa, the demand for horticultural products can be expected to rise as the economies of the East African States develop. Because of the high nutritive value of horticultural crops generally and due to the excellent market potential which exists for many vegetable, fruit and ornamental crops, it is likely that the production of many of these crops will increase. With more intensive and more concentrated production, pest and disease problems are likely to become more serious. Crops of high cash value are particularly subject to severe pest losses since even slight damage can result in a major loss in terms of quality and cash return. Furthermore, only high value crops can justify the expenditure necessary to control pests by spraying.

With intensive crop production, there is often a complex of pests to be considered at any given time, each calling for special methods of control. Even when resistant cultivars can be produced by the plant breeder, they will usually resist or tolerate only one major group of insects or perhaps only single species of the pest. Furthermore, resistance in horticultural crops may be associated with undesirable characteristics which may not be commercially acceptable. Kearns (1965) stated that 'each crop produces its own special problems which can only be solved with the joint knowledge of the horticulturist, the entomologist, the mycologist, the weed control expert, the spray chemist and the engineer, although the horticulturist is the final judge of the success of the operation'.