Integrated effect of insecticide and sex pheromone on the tomato leafminer, Tuta absoluta (Lepidoptera: Gelechiidae)

Abstract

The tomato leafminer, Tuta absoluta (Meyrick), is currently a major threat to tomato globally. Growers in Ethiopia rely on insecticides to control the pest, which is not sustainable because of the insect's ability to develop resistance fast. The rational use of pesticides is useful to delay pesticide resistance. The integrated effect of sex pheromone and insecticide in the population of the tomato leafminer and its damage on tomato was investigated for two seasons between 2020 and 2021 at Melkassa center of the Ethiopian Institute of Agricultural Research (EIAR). Treatments consisted of trapping using sex pheromone alone, insecticide use alone and a combination of trapping using sex pheromone and insecticide (integrated treatment) along with the untreated control. Four fields, each with three replicates of plots for each treatment were used by keeping each field wide apart to minimize the movement of adult population of the insect. Treatment effects were assessed by counting the immature stages of the insect and damage both on the leaves and tomato fruits. Treatments differed significantly for mining larvae but not for the number of eggs. Leaf damage was significantly higher in the untreated control than in the rest of the treatments. In both years, similar trends of results for the percentage of damaged fruits were observed, which was lowest in the integrated treatment followed by insecticide alone, pheromone trap alone and untreated control. Results from this study suggest the need to integrate pheromone traps with insecticides to achieve better protection from Tuta absoluta damage on tomato.