Bacillus thuringiensis propagated in bio-urine media as a biological control of termite Coptotermes curvignathus and armyworm Spodoptera litura

Abstract

Biological control using entomopathogenic bacteria Bacillus thuringiensis is in increasing demand because of its specific target toxicity, safe for natural enemies as well as pollinating insects. Propagation media for B. thuringiensis greatly determines the success of spores number produced and toxicity level to insect pests. This study aimed to record the spore density of indigenous isolates of South Sumatera propagated in bio-urine and 5% molasses media and their toxicity level against termites Coptotermes curvignathus and armyworm Spodoptera litura. The research was conducted at Biological Control Laboratory, Plant Protection Study Program, Faculty of Agriculture, UNSRI, from March to June 2019. The study was designed with Factorial Completely Randomized Design, using isolates as many as 3 isolates with 3 media treatments (bio-urine, bio-urine + 5% molasses, and Nutrient Broth) and 5 replications. The bio-assay used worker caste termites and 3rd instar armyworms. The results showed that a mixture of bio-urine and 5% molasses produced higher number of spores compared to bio-urine media only. The use of NB as a control showed higher spore production compared to the 2 other treatments. The mortality rate of Coptotermes termite was higher than the mortality rate of armyworms. Death symptoms of insect pests were indicated by the presence of wet rot and color change (blackish).