Biocontrol competence of Beauveria bassiana, Metarhizium anisopliae and Bacillus thuringiensis against tomato leaf miner, Tuta absoluta Meyrick 1917 under greenhouse and field conditions

Abstract

Tomato is one of the most important crops grown under both greenhouse and field conditions throughout the world. Its production is highly challenged by infestation of leaf miner insect, Tuta absoluta Meyrick regardless of excessive insecticide application. The chemical insecticides results insect resistance, environmental pollution, and health problems and there is urgent need for management options such as integrated pest management (IPM) to obviate these problems. Thus, the present study aims to evaluate the effectiveness of single and combination treatments of entomopathogens; Beauveria bassiana, Metarhizium anisopliae, Bacillus thuringeinsis, and an insecticide against T. absoluta under greenhouse and field conditions. Two varieties (Awash and Venes) of tomato for greenhouse experiment and one (Gellila) variety for field experiment were used with Tutan36%SC (insecticide with active ingredient of Chlorphenapyr 36%SC) and untreated plots as positive and negative controls, respectively. The results showed significant leaf and fruit damage reduction in all the treatments. B. bassiana-AAUB03, M. anisopliae-AAUM78, and B. thuringiensis-AAUF6 showed the highest (93.4%, 89.7% and 90.1%) leaf and (93.5%, 94.4% and 95%) fruit protection under greenhouse condition. The combined treatments improved leaf protection efficacy up to 95.3% under field condition. When the entomopathogens were combined with half or quarter reduced concentrations of Tutan36% SC, it showed 94.4% of pest protection. In all the treatments, 72–96% of marketable fruit was obtained as par insecticide treatment scored 85–93%. All the entomopathogens did not cause any adverse effect on the growth of tomato rather improved shoot length, shoot branching, leaf and fruit numbers. Therefore, application of entomopathogens in single, consortium or in combination reduced the recommended concentration of Tutan36%SC to control T. absoluta.