Management of Onion Thrips [Thrips tabaci Lind. (Thysanoptera: Thripidae)] on Onion Using Eco-Friendly Cultural Practices and Varieties of Onion in Central Zone of Tigray, Ethiopia

Onion thrips, Thrips tabaci (Thysanoptera: Thripidae) is a major insect pest constraining onion production in the Central Zone of Tigray. Therefore, field experiment was conducted at Axum Agricultural Research from November 2015 to April 2016 to manage onion thrips using multiple techniques. The experiment was laid out in a randomized complete block design (RCBD) with split plot arrangement and replicated three times. Onion varieties Bombay Red and Nasik Red were used as main plot treatments and intercropping onion with one or two other vegetables including, cabbage, carrot and lettuce, as subplot treatments. Treating onion with the insecticide lambda-cyhalothrin (Karate) 5% EC and untreated sole onion were included as standard and control checks. Results showed that intercropping onion with cabbage, onion with cabbage + carrot and onion with cabbage + lettuce significantly reduced T. tabaci population by 58.47, 63.81 and 50.51%, respectively at higher infestations. Similarly, intercropping onion with cabbage, onion with cabbage + carrot and onion with lettuce + carrot showed a better effect in reducing thrips damage severity by 23.37, 23.09 and 17.66%, respectively, at higher infestations. Predatory thrips were observed on onion intercrops except the Karate 5% EC treated check. The highest marketable onion yield (35.52 t/ha) was obtained from onion intercropped with carrot and lettuce, though not significantly different from the untreated check. The lowest (23.54 t/ha) was obtained from onion intercropped with cabbage + lettuce. However, onion intercropped with lettuce gave the highest gross income (307344 ETB/ha). The lowest gross income was recorded from the insecticide treated plot (194583 ETB/ha). The study clearly showed that intercropping onion with other vegetables reduced the number of onion thrips and their damage on onion in the central zone of Tigray and hence can form an integral component in the integrated management of thrips on onion.