Characteristics of Bacillus thuringiensis isolates indigenous soil of South Sumatra (Indonesia) and their pathogenicity against oil palm pests Oryctes rhinoceros (Coleoptera: Scarabaeidae)

Abstract

Abstract. Pujiastuti Y, Arsi, Sandi S. 2020. Characteristics of Bacillus thuringiensis isolates indigenous soil of South Sumatra (Indonesia) and their pathogenicity against oil palm pests Oryctes rhinoceros (Coleoptera: Scarabaeidae). Biodiversitas 21: 1287-1294. Bacillus thuringiensis is a gram-positive, entomopathogenic bacterium that could be isolated from soil and be used to control various plant pests. Oryctes rhinoceros is an important pest in oil palm. Application of B. thuringiensis-based bioinsecticides is an alternative in controlling these pests. The purposes of this study were to isolate and identify B. thuringiensis bacteria from the soil of South Sumatra, production of B. thuringiensis-based bioinsecticides and to test their toxicity to O. rhinoceros larvae. The study was conducted in several cities/districts in the province of South Sumatra. Soil samples were taken from various habitats and B. thuringiensis isolates were grown on NGKG agar media. Among 76 soil samples (6 districts and 2 cities) B. thuringiensis colonies were obtained leading to 24 isolates of B. thuringiensis. Toxicity screening tests for armyworm Spodoptera litura were 55.79% (53 isolates) and their mortality to 25.26% O. rhinoceros larvae (24 isolates). From these isolates whose effectively killed O. rhinoceros larvae, 10 isolates were taken and propagated with Nutrient Broth (NB) and biourine enriched with 5% molasses. Number of spores produced was counted during 24, 48 and 72 hours. Furthermore, a bioassay test was carried out on O. rhinoceros larvae for 7 days. Isolate of KJ3P1 caused the highest mortality of O. rhinoceros larvae after 7 days of observation. SDS Page resulted in KJ3P1 and KJ3R5 isolates showing several bands whose content of various types of protein molecular weight. Isolation of B. thuringiensis in South Sumatra produced 2 isolates potentially to be active ingredients in production of bioinsecticides which were effective in killing O. rhinoceros larvae.

Propagation Of Entomopathogenic Bacteria Bacillus Thuringiensis In Various Agricultural Waste and Its Effectivity Against Oryctes Rinoceros (Coleoptera:Scarabaeidae)

“…1d), changing in external color of the body becomes one of the indicators of the infection process and the death of the test larvae. This was also reported by [9], [19] [20] and [21] the process of death of the test insects begins with the poisoning process in the midgut, while in the process there appears to be a change in morphology (color) on the body of the test insect.…”

Effectivity of Bacillus thuringiensis from Soil in Freshwater Swamps against Epilachna sp. Larvae

“…In the treatment with the highest density of 10 8 spores/mL (L5), the highest mortality was 40%. This was supported by Pujiastuti et al (2020b) which stated a large number of spores ingested in the larvae's midgut will cause many deaths. In the midgut, proteins present in Bt were broken down into smaller molecules, which were called toxins (Sansinenea, 2012.).…”

“…However, it appeared treatment of 10 5 spores ml showed the highest rate of change in larvae became pupa (82%) and pupae became adult (62%). This showed that a small number of sporeswill cause low mortality (Pujiastuti et al, 2020b). Low mortality in larval treatment caused a chance of larvae to live and change to pupal stage.…”

Diversity of Soil Inhabiting Arthropods in Intercropping of Chili and Chinese Mustard Green Applied With Bacillus thuringiensis Based Bio-Insecticides and Synthetic Insecticides Treatment

“…B. thuringiensis tend to be specific attacking insect pests of the Lepidoptera order [26]. In some target insects, Cry proteins merely were sufficient to intoxicate larvae by destroying enough midgut epithelial cells [27].…”