Response of new insecticides against major insect pests of tomato in West Shoa, Ethiopia

Abstract

The tomato (Lycopersicon esculentum Mill.) is cultivated in different parts of Ethiopia in the field as well as in the glasshouse for consumption and processing. Helicoverpa armigera, Tuta absoluta and Liriomyza spp. are damaging insect pests, specifically the tomato crop. In the present study, the laboratory and glasshouse studies were carried out at the Ambo University laboratory, whereas the field experiments were carried out in 2 districts of West Shoa of Ethiopia. The experiments were conducted to evaluate the efficacy of new insecticides against T. absoluta, H. armigera and Liriomyza spp. on tomato crops. The laboratory results showed that the tested insecticides were significantly (p £ 0.05) different after 72 hr of treatment application. The mean mortality was obtained by Benezer Plus 38.5 % E.C and Delta 2.5 % E.C at maximum rate which proved the most effective and gave ((84.03 ± 1.57; 84.42 ± 1.46 %), (85.03 ± 1.48; 84.02 ± 1.59 %) and (78.27 ± 1.27; 68.03 ± 1.18 %)) against T. absoluta, H. armigera and Liriomyza spp. respectively. The glasshouse and field results also revealed that there was a significant reduction in the larval population of T. absoluta, H. armigera and Liriomyza spp. in protected plots as compared to unprotected plots after spraying of insecticides, which ultimately increased the % of marketable yield in sprayed plots. Therefore, the combination of Phenthoate and Emamectin benzoate (Benezer plus 38.5 % E.C) and Deltamethrin (Delta 2.5 % E.C) was found more effective at the maximum rate against T. absoluta, H. armigera and Liriomyza spp. on tomato crops in the glasshouse as well as under open farmers' field conditions. Therefore, these findings could guide farmers and policymakers in selecting cost-effective insecticide regimes.