BIOCONTROL AGAINST INSECT PESTS BY Bacillus thuringiensis ISOLATED FROM ORGANIC AGRICULTURAL FARM

Abstract

Insects are a significant factor in the destruction of agricultural crops. The management must be done in such a way that is free of potentially dangerous chemicals and that remains environmentally benign. Bacillus thuringiensis is a soil bacterium whose main characteristic is the development of parasporal crystalline inclusions that contain the crystal protein which possesses insecticidal effects. The study’s primary objective is to evaluate the insecticidal activity of Bt as a biocontrol agent against insects pests. A total of 60 soil samples were randomly taken from four organic farms in Dharan, Tarahara, Itahari and Jhumka, Nepal. The bacteria were isolated using sodium acetate selection method and were conventionally identified to determine whether the isolates were Bt. Four isolates namely SR1, SI7, ST9 and SJ11 displayed the characteristics of Bt which were bioassayed against two insect pests, Spodoptera frugiperda and Myzus persicae. Bioassay was carried out by preparing crystal/spore mixture (1mg/ml) and feeding it to the insects which were grown in the laboratory by placing them in the disposable plastic glass and directly dipping maize and bean leaves before being given to the appropriate insect. All the four isolates showed insecticidal activity against the insect pest and gave positive result with great potentiality to infect and manage S. frugiperda and M. persicae. The mean difference between treatment and control was statistically significant (p>0.05). The findings showed that the use of living organisms to control pests by implementing bioactive agents or microorganisms that are entomopathogenic to insect pests is an appealing course of action and a sustainable approach for crop protection because they degrade quickly, resulting in fewer exposures and primarily preventing pollution issues brought on by synthetic pesticides.