Insecticidal activity of supernatant and crude extract of Bacillus thuringiensis-based bio-insecticide towards oil palm pests Oryctes rhinoceros (Coleoptera: ‘/Scarabaeidae)

Abstract

Oryctes rhinoceros is an important pest in oil palm plants. Larvae and imago are stadia which attack plants. Control by using synthetic chemical insecticides often create a negative impact on non-target insects and the environment. B. thuringiensis can be used as an alternative. The aim of the study was to study the insecticidal activity of B. thuringiensis isolates from South Sumatra on the larvae of Oryctes. The study was conducted at Entomological Laboratory, Department of Plant Protection, Faculty of Agriculture, Sriwijaya University, from March to May 2019. The study was designed by a factorial complete randomized design with two factors in the form of Bt isolates (four isolates) and the presence of spores (crude extract and supernatant) with each repeated 3 times. The treatments were B. thuringiensis isolates propagated in Biourin media and applicated in the form of crude and supernatant. B. thuringiensis propagated in NB media was used as control. Tested insects were 1st instar larvae of Oryctes. The results showed application of crude solution of B. thuringiensis resulted in higher mortality compared to supernatant treatment. It was assumed in crude solution there was a mixtured of spores and proteins compared with the solution of the supernatant which only contains spores. KJ3P1 isolate was able to cause the highest mortality in crude treatment.