Evaluation of botanicals for onion thrips, <i>Thrips tabaci</i> Lindeman, (Thysanoptera: Thripidae) control at Gum Selassa, South Tigray, Ethiopia

Abstract

Field studies were conducted for two consecutive years (2013 and 2014) to determine the effectiveness of different plant extracts and synthetic chemical insecticides for the control of onion thrips (Thrips tabaci) at Adigudom, Southern Tigray, Ethiopia. Two chemical insecticides including dimethoate 40% E.C and Lambda-cyhalothrin (Karate 5 EC), and five botanical extracts obtained from neem (Azadirachta indica A. Juss), Mexican marigold (Tagetus minuta L.), tree tobacco (Nicotiana glauca Graham) and Jimson weed (Datura stramonium L.) were tested for their controlling effect on onion thrips. The population dynamics of the thrips was monitored and population counts were made before and after the application of each of the treatments. The two years combined analysis indicated that there was a significant difference (p<0.05) in onion bulb yield where dimethoate, Tree tobacco, Karate, and Mexican marigold recorded significantly higher onion bulb yield than the control. Thirty and 37% more bulb yield was obtained in the Tree tobacco and dimethoate treated plots than in the control. Karate has had the highest effect in reducing thrips pest population in year one, though was on par with that of dimethoate, did well in the second year contributing to significant yield improvement against the control. There was no statistically significant difference among treatments in plant height, leaf number and bulb weight. From among the botanicals tested, tree tobacco had the best performance in controlling onion thrips and was comparable to those of dimethoate and Karate.

Management of Onion Thrips (Thrips tabaci) in Organic Onion Production Using Multiple IPM Tactics

“…Onions sprayed with spinosad + neem oil had fewer T. tabaci and produced higher yields than onions that were unsprayed, regardless of mulch type or onion cultivar. Previous studies in onion production regions of the United States and Pakistan have shown that biopesticides are effective for reducing T. tabaci densities in onion [ 47 , 57 , 58 , 59 , 60 ]. However, efficacy depends on the biopesticide applied.…”

“…Several botanical extracts also have been evaluated for T. tabaci control in onions. Azadirachtin, derived from the neem tree seeds or leaves ( Azadirachta indica Juss), provided moderate reductions in T. tabaci densities in studies conducted in the Pakistan [ 58 , 60 ] and feeding damage in studies conducted in New York, United States [ 48 ], but improvements in yield were inconsistent. In studies conducted in Ethiopia and Pakistan, Fitiwy et al [ 60 ] and Khaliq et al [ 58 ], respectively, reported reductions in thrips densities of 17.2% and >60% using extracts of Datura spp., respectively.…”

“…Azadirachtin, derived from the neem tree seeds or leaves ( Azadirachta indica Juss), provided moderate reductions in T. tabaci densities in studies conducted in the Pakistan [ 58 , 60 ] and feeding damage in studies conducted in New York, United States [ 48 ], but improvements in yield were inconsistent. In studies conducted in Ethiopia and Pakistan, Fitiwy et al [ 60 ] and Khaliq et al [ 58 ], respectively, reported reductions in thrips densities of 17.2% and >60% using extracts of Datura spp., respectively. Khaliq et al [ 58 ] also found a significant reduction of T. tabaci using tree tobacco ( Nicotinia glauca Graham), as well as a similar yield to the pyrethroid synthetic insecticide lambda-cyhalothrin.…”

“…Khaliq et al [ 58 ] also found a significant reduction of T. tabaci using tree tobacco ( Nicotinia glauca Graham), as well as a similar yield to the pyrethroid synthetic insecticide lambda-cyhalothrin. Additionally, some of the botanical extracts may be more available and affordable in parts of the world where onions are grown, such as the United States and Canada [ 60 ]. Regardless of onion production region, future research should focus on identifying effective rotations of biopesticide products and using action thresholds to reduce potential insecticide resistance.…”

The Major Biological Approaches in the Integrated Pest Management of Onion Thrips, Thrips Tabaci (Thysanoptera: Thripidae)

“…There have been trials to establish aromatic insecticides from various plant species to control onion thrips at field and greenhouse conditions and the following have been recommended: Artemisia arborescens, Azadirachta indica L., Chrysanthemum cinerariifolium, Datura stramonium, Dodonaea angustifolia L., Dianthus caryophyllus, Melaleuca alternifolia, Nicotiana glauca, Origanum majorana, Ocimum gratissimum, Rosmarinus officinalis, and Tagetes minuta (Fitiwy et al 2015;Omosa et al 2016;Prabhu et al 2011;Shiberu & Negeri 2014;van Tol et al 2007).…”