Insecticide resistance management against thrips (Thysanoptera: Thripidae) on onion in the central Rift Valley of Ethiop
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ORIGINAL RESEARCH ARTICLE
Insecticide resistance management against thrips (Thysanoptera: Thripidae) on onion in the central Rift Valley of Ethiopia Belete Negash 1 & Ferdu Azerefegn 1 & Gashawbeza Ayalew 2 Received: 17 April 2019 / Accepted: 18 February 2020 # The Author(s) 2020
Abstract Two field experiments were conducted in the Central Rift Valley of Ethiopia in the hot and cool dry seasons of 2016/2017 with the objective to develop an insecticide resistance management program on thrips infesting onion. The first experiment dealt with the evaluation of four different insecticides namely profenofos, λ–cyhalothrin, imidacloprid, and spinetoram in different sequences on thrips population and their effect on yield. The second experiment examined the effect of admixing the surfactant organosilicone with imidacloprid, spinetoram and dimethoate. A Randomized Complete Block Design with three replications was used for both experiments. Data on number of thrips, bulb yield and economic returns were collected. The insecticide imidacloprid and spinetoram resulted in fewer numbers of thrips and higher yields than profenofos and λ –cyhalothrin. Application of the more effective insecticides when the thrips population was high followed by less effective insecticides resulted in better control and higher economic return. Surfactant added insecticides gave a fewer numbers of thrips and higher yields than the corresponding insecticides applied without surfactant. The sequential application of spinetoram and imidacloprid with less effective λ-cyhalothrin and profenofos by mixing with adjuvant are recommended for thrips control as an integral component of thrips management in the Central Rift Valley of Ethiopia. Keywords Thrips . Resistance . Management . Insecticides . Rotation . Surfactant
Introduction Onion (Allium cepa L.) is a widely grown vegetable by small and large-scale farmers in Ethiopia covering an area of 48,443.36 ha with the total production of 374,704 tons (CSA 2016). The national average productivity of onion in Ethiopia is 7.734 t ha−1(CSA 2016) which is low compared to the world average of 19.49 t ha−1(FAOSTAT 2012). This low productivity could be attributed to poor agronomic practices and pests damage (Tadele and Amin 2014). Onion thrips, * Belete Negash [email protected] Ferdu Azerefegn [email protected] Gashawbeza Ayalew [email protected] 1
College of Agriculture, Hawassa University, Hawassa, Ethiopia
2
Ethiopian Institute of Agricultural Research, Melkassa Research Center, Adama, Ethiopia
Thrips tabaci Lind. (Thysanoptera: Thripidae) is considered as the most economically important pests of onion worldwide (Gachu et al. 2012). Thrips are major pests in all oniongrowing areas of Ethiopia and can routinely reduce bulb yields by 23–85% (Tadele and Mulugeta 2014). Bekele et al. (2006) reported 10 to 85% onion bulb yield losses due to onion thrips at Upper Awash Agro Industry areas in Central Ethiopia. The use of insecticides is the most common management tactic for onion thrips infestations in Ethiopia
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