The effect of corn oil concentrations on the activity of bacillus thuringiensis strain kurstaki and aizawai against the fall armyworm

Abstract

Spodoptera frugiperda, also known as Fall Armyworm (FAW), is a migratory insect pest that infests several crops, especially cereals such as maize, which is one of the major food crops in Uganda. The pest has caused significant economic losses and food insecurity in Uganda and many other parts of the World. One of the conventional methods of managing this pest has been through using chemical pesticides, but this poses serious risks and negative impacts on human health and the environment. The use of entomopathogenic bacteria, such as Bacillus thuringiensis (Bt), has proven to be a safer and more eco-friendly alternative for controlling FAW. Previous studies have examined the effect of different corn oil concentrations on various entomopathogens such as fungi and some other Bacteria strains. This study aimed to investigate the efficacy of combined Bt strains of aizawia and Bt strain kurstaki in different corn oil concentrations. The data collected was analyzed using Kruskal Wallis rank sum tests from R Studio statistical package. At p-value =0.0015, it shows that the activity of the combined strains of B.thuringiensis attains optimum activity at the corn oil concentration of 15-20%. The results indicated that the combined B.thuringiensis strains Kurstaki and Bt strains aizawia were more effective in causing mortality of 3rd instar larvae in the oil-based emulsion. The findings also suggested that moderate concentrations of oil in suspension with combined Bt strains were more effective against FAW.