Potency of Bacillus thuringiensis in liquid formulation as a biological agent in controlling larvae of Oryctes rhinoceros (Coleoptera:Scarabaeidae)

Abstract

Propagation of B. thuringiensis in agricultural liquid waste media can be done because the waste still contains nutritional components which contain carbon and nitrogen. The aim of research was to study B. thuringiensis in a liquid formulation with high toxicity against Oryctes larvae. Parameters of observation were spore density, larval mortality and symptoms of both infection or death larvae. Experimental was designed as a completely randomized design with 6 treatments and 4 replications. Oryctes larvae used were 3rd-instar. The treatments were 1). Tofu liquid waste; 2) Tofu Liquid Waste + Bio-urine (1:2); 3) Tofu Liquid Waste + Bio-urine (1:1); 4) Tofu Liquid Waste + Bio-urine (2:1); 5) Bio-urine and 6) NB media (as control). The results showed the highest spore density was found in tofu liquid waste propagation media and biourine (1:2). The highest larval mortality was shown in treatment of Tofu Liquid Waste + Bio-urine (1:2), which was 91.67%. Observations on the symptoms of infection and death in tested larvae were indicated by changes in color of integument and fragility of the larva's body. Bio-insecticide with active ingredient of B. thuringiensis in liquid formulation has potency to be used as biological agent for controlling O. rhinoceros larvae.