Study on Bacillus thuringiensis Indigenous Highland of South Sumatera–Based Bioinsecticide Towards Lepidopteran Insect Pests

The objectives of research were 1) to explore the presence of Bacillus thuringiensis from highland soil of South Sumatera; 2) to investigate crystal proteins and their toxicity against diamondback moth Plutella xylostella and armyworm Spodoptera litura; and 3) to produce B. thuringiensis – based product of the most promising B. thuringiensis isolate. Exploration of soil resulted 33 B. thuringiensis isolates in which 21 isolates were toxic against P. xylostella and 15 isolates were toxic towards S.litura. Two isolates, namely SASU and KATB, were very toxic to both insects. Developing of those isolates as bio-insecticide was done in three main growth media i.e. coconut water, soybean soaking water, tofu liquid waste, mixtures of coconut water and soybean soaking water (1:1. v/v), mixtures of coconut water and tofu liquid waste (1:1. v/v), and Nutrient Broth, as control. Total Viable Spore Count (TVSC) showed spore product was ranged from 2.22 x 106 until 8.98 x 108spores/ml resulted in high mortality of P. xylostella and of S. litura, indicating the presence of toxic crystal protein