Pest management in horticultural crops: progress and prospects

This paper reviews the status of entomological research on horticultural crops (citrus, vegetables, roots and tubers) in Ethiopia. Concerted research efforts on horticultural crop entomology in this country started in the early 1980s. Initial efforts concentrated on pest survey, identification, economic importance and their geographical distribution. Scale insects, aphids (as virus vectors), and citrus psyllid on citrus; fruit worms on tomato; onion thrips on onions; and potato tuber worm on potato have been identified as the major pests that inflict heavy damage and cause considerable yield losses. Significant progress has been made in establishing and implementing IPM programmes against the major pests. Use of mineral oil sprays timed to coincide with the peak breeding period of the red scale (Aonidiella aurantii) has enabled to reduce the frequency of pesticide application from about a dozen to 2-3 sprays per year, thus conserving natural enemies that play a significant rold in the IPM of this insect; some progress has also been made in understanding the significance of the natural enemy fauna in the natural biological control of important pests. Parasitoids introduced from abroad and released against scle insects on cirus did not get established. Seasonal changes in the population of fruit worms on tomato have been studied, and sources of host plant resistance have been identified; the critical period of damage has also been deremined. Studies on the population dynamics of onion thrips have been carried out and peak periods of damage have been identified; the rate and frequency of insecticide application have been determined. Promising results have been identified; the rate and frequency of insecticide application have been determined. Promising results have been obtained with botanical control of onion thrips. Future research will focus on an IPM approach with more emphasis on conservation of natural enemies, use of host plant resistance and natural products, wherever applicable.