Management of onion Thrips (Thrips tabaci L.) (Thysanoptera: Thripidae) through Botanical Insecticides and Improved onion Varieties in central Tigray, Ethiopia

Abstract

A field experiment was conducted in 2024 under irrigated conditions in hadash tekli tabia to investigate the integration effect of botanical insecticides and improved onion varieties on the management of onion thrips. A randomized complete block design with two factors and three replications was used. Factor one includes onion varieties (Adama red and Bombay red) and factor two consists of four botanicals, namely, Lantana camara leaf, Jatropha curcus seed, Ricinus communis seed, and Phytolacca dodecandra seed, one synthetic insecticide (Karate 5% EC) and one control (spaying only water) three times spraying for each at the interval of 10 days. Data were recorded on Thrips incidence, mortality, leaf severity yield-related parameters, and yield of onion analyzed using GenStat software version 18. The highest mortality percentage (80.18%), lowest incidence (23.3%), lowest leaf severity scale (1.3), highest leaf number (17.17), wide bulb diameter (5.39 cm), maximum marketable yield (12991 kg ha⁻¹), highest avoidable yield loss (67.7%), and highest MRR (548808%) was recorded from the Bombay variety treated with Ricinus communis. The lowest mortality (-32.58%), and highest incidence (70%), highest leaf severity scale (4.93), minimum leave number (6.97), narrow bulb diameter (2.05 cm), and minimum marketable yield (3521 kg ha⁻¹) were recorded on untreated Adama red. Among botanical insecticides, Ricinus communis recorded the highest bulb weight (57.89 g), longest bulb length (4.24cm), and highest plant height (54.9cm) however the smallest bulb weight (25.19 g), shortest bulb length (2.3cm), and plant height (33.cm) were recorded from control plot. Between varieties Bombay red recorded the highest bulb weight (48.5 g), longest bulb length (3.93cm), and highest plant height (51.48cm) in comparison to Adama red. In conclusion, the Ricinus communis-treated Bombay red showed the highest mortality of onion thrips, lowest incidence, lowest leaf damage, highest marketable yield, and MRR. Thus, it can be recommended that farmers use the integration of botanical insecticides and improved onion varieties) to reduce the onion thrips damage thereby enhancing onion productivity and improving environmental safety.