EFFECT OF INTERCROPPING AND BOTANICAL EXTRACT ON POPULATION ABUNDANCE OF INSECT PESTS AND THEIR ASSOCIATED NATURAL ENEMIES ON TOMATO (Lycopersicon Esculentum (MILL.) IN EASTERN ETHIOPIA

Abstract

Tomato is one of the most important vegetable crops grown in Ethiopia. Its production is constrained by arthropod pests and diseases. Fruit borer (Helicoverpa armigera), Whiteflies (Bemisia tabaci), Aphids (Aphis spp), leafminer (Tuta absoluta), Serpentine leafminer (Liriomyza sp), Thrips sp and two spotted spidemites (Tetranchus urticae Koch) are the major economic pests recorded in the study area. The research was initiated to evaluate the potential of intercropping and plant extract to reduce pests on tomato and their associated natural enemies using irrigation systems from January to May 2021 at Haramaya University, Rare research station. The treatments, tomato - onion (Allium cepa L.), tomato - head cabbage (Brassica Oleracea), tomato - common bean (Phaseolus vulgaris) intercropping and sole tomato(control), tobacco (Nicotiana tabacum) leaf extract, and Karate 5% EC (Standard check) were used. The experiment was laid out in a randomized complete block design (RCBD) with four replications. Tobacco leaf extract was applied weekly for eight times whereas karate 5%EC was applied at ten days interval for six (6) times until the first fruit harvest. The data on the population of the insect pests were recorded weekly starting on the 21st day after transplanting for eight (8) weeks. The parasitoids population was recorded from samples in the laboratory after their emergence from the host. The over all result indicated that all intercropping systems and tobacco leaf extract significantly (P < 0.05) reduced the population of these insect pests compared to sole tomato. The highest population reduction was recorded on tobacco leaf extract followed by tomato – onion. The companion crops harbored the parasitoids of diverse species in the highest level, but tobacco extract was comparable to untreated control. Tomato onion intercropping and tobacco leaf extract raised the best economic performances upon high net benefits and benefit cost ratio. Therefore, tomato onion intercrops and tobacco leaf extract can be used as the first options in boosting tomato production as an alternative to karate 5%EC. Further study on the mechanisms of the effectiveness of botanical extracts with rate and frequency and also intercropping and detailed morphological and molecular-based parasitoid species identification and their ecological host ranges are of utmost importance in the sustainable IPM strategies in tomatoes