Insecticides for the management of tef epilachna (<i>Chnootriba similis</i> Thunberg, coleoptera: coccinellidae) in barley in Wolaita Zone, Southern Ethiopia

Abstract

Tef epilachna, Chnootriba similis, is an important pest of cereal crops in Ethiopia. It causes significant yield loss on barley under heavy infestation. The efficacy and application time of five foliar insecticides were evaluated to control C. similis on barley in two districts of Wolaita, southern Ethiopia during the short “Belg” and the main “Meher” rainy seasons of 2020. The trial was factorial in a randomized complete block design with three replications. The treatments were combinations of five insecticides (carbaryl, diazinon, imidacloprid, λ-cyhalothrin, malathion) and two application times (early and late). Early applications (tillering stage) of insecticides were either better or on par with the late applications (booting stage) in the two seasons and locations in terms of mortality of larvae, leaf damage and grain yield. Higher larval mortalities were recorded for the insecticides λ-cyhalothin (87 - 100%), carbaryl (84 – 100%), diazinon (78 – 99%), malathion (86 – 100%), and imidacloprid (71 – 97%). Barley protected with insecticides against C. similis had lower leaf damage and resulted in significantly higher yield. The insecticides carbaryl, λ-cyhalothrin, malathion, diazinon, and imidacloprid, applied at the early tillering stage of barley can effectively control C. similis on barley. The insecticide λ-cyhalothrin that consistently provided higher protection and gave the highest return is the best choice for the control of C. similis.