Evaluation of shallot cultivars against onion thrips, Thrips tabaci Lindeman (Thysanoptera: Thripidae) in Bishoftu, Ethiopia

Abstract

Onion thrips, Thrips tabaci Lindeman (Thysanoptera: Thripidae), is a worldwide pest of allium crops that can reduce shallot yield by more than 50% and even more problematic when it transmits iris yellow spot virus (Family Bunyaviridae, Genus Tospovirus, iysv). Because of its cryptic nature, it is difficult to control thrips merely with insecticides. Thus, a field experiment was conducted to investigate the effect of shallot cultivars against T. tabaci. The study was conducted between June 2017 and March, 2018 in two locations at Debre Zeit Agricultural Research Center (dzarc), Ethiopia. Ten shallot cultivars were evaluated in a complete randomized design with three replications, by counting the number of thrips larvae at weekly interval and recording leaf damage percentage. Most of the cultivars had shown a significant difference (P<0.05) for all recorded evaluation parameters. Five out of the 10 tested cultivars scored low thrips population had very little leaf damage and were considered resistant to T. tabaci. Visual assessment to shallot plant canopy indicated that all the cultivars has shown low damage symptom. Moreover, the result revealed that the registered shallot varieties namely Huruta and Minjar were superior in bulb yield and resistant level to thrips damage. Our findings indicate that the presence of thrips resistant/tolerant shallot cultivars in the germplasm collections at dzarc and the potential for developing T. tabaci resistance shallot cultivars as part of an overall integrated pest management strategy. Therefore, these cultivars could be used by complementing them with insecticides and cultural practices to manage onion thrips populations.