Yulia Pujiastuti et al, 2022 | Abstract 145 BIOVALENTIA: BIOLOGICAL RESEARCH JOURNAL e-ISSN: 2477-1392 Vol. 8 No. 2, Nov 2022 Study of Effectivity Bacillus thuringiensis Based Bio-Insecticide Against Oryctes rhinoceros Larvae at Shade House Yulia Pujiastuti 1* , M. Ridwan 1 , H. Saputra 1 , M. Agusrafil 1 , A. Nurnabila 1 , Henny Hendarjanti 2 1 Plant Protection Department, Faculty of Agriculture, Sriwijaya University, South Sumatera, Indonesia 2 PT. Astra Agro Lestari. Kawasan Industri Pulo Gadung, Blok OR 1-2, Jatinegara, Jakarta Timur 13920, Jakarta, Indone- sia *Corresponding author E-mail address: ypujiastuti@unsri.ac.id (Yulia Pujiastuti). Peer review under responsibility of Biology Department Sriwijaya University Abstract Oryctes rhinoceros is an important pest in oil palm plantations. Adult stage of the beetle causes damage, however larval stage is very important to be controlled to break the cycle of life. An entomopathogenic bacterium Bacillus thuringiensis is one of biological agents to control these insects. Its toxic protein content provides specific insect targets as stomach poison. Objective of the research was to study the impact of B. thuringiensis propagated in bio-urine enriched with 5 per cent molasses towards Oryctes larvae. The research was carried out in the shade house of Plant Protection Study Program, Faculty of Agriculture, Sriwijaya University from August to No- vember 2021. Experiment was designed in a randomized complete block design with 7 treatments and 4 replications. A total of 20 ml of bio-insecticide was dissolved in 280 ml of water, sprayed evenly on the soil mixed with male palm flowers as feed of larvae. The treat- ments were 6 isolates of B. thuringiensis isolated from soil in oilpalm plantation, namely with codes: C14, C15, A15, OJ, BK, and LK as well. The results showed density of B. thuringiensis spores in bio-urine media was different in each isolate. The highest spore density in isolate code LK was 4.83 x 10 10 spores/ml and the lowest (in isolate A15) was at 3.5 x 10 10 spores/ml. Mortality rates were signifi- cantly different between isolate treatments starting from day 3 to day 12 of observation. C15 isolate lead the highest mortality rate of 100% on day 12 while other isolates showed mortality data below 100% (88-98%). Body weight and length showed significantly differ- ences on days 0, 6 and 12 after application. Symptoms of infection begin with a change in skin color from white to brown, dark brown and black. Death is characterized by a soft body texture and wet rot. Keywords : Bacillus thuringiensis, Bio-insecticide, oil palm, mortality, Oryctes rhinoceros Received: June 18, 2022, Accepted: July 23, 2022 1. Introduction Bacillus thuringiensis is an entompathogenic bac- terium and has been used to control various species of insect pests. This bacterium is characterized by the pres- ence of spores and proteins causing mortality in target insects. Proteins content of each isolate show different molecular weights and posses different toxicity in differ- ent insect species [1]. Because of its uniqueness, the usage of B. thuringiensis as a biological agent is increasing. Propagation of B. thuringiensis in waste media produces spores and proteins. Waste media contains sufficient or- ganic matter to multiply B. thuringiensis. Several re- searchers have used industrial waste [2], [3], food waste [4] and other agricultural waste [5] as a medium for B. thu- ringiensis propagation. When it was tested to target insects and resulted high mortality of insects [6]. Oryctes beetle as one of important pests in oil palm plantations must be controlled [7]. These pests induce damage to oil palm plants by eating young leaves or coco- nut leaves causing the death of young plants [8]. Life cycle of oryctes beetle ranges from 6-9 months and adult live up to a year [9]. In the field, it is often found overlapping of generations, which means all life stages of oryctes are found in nature [10]. Thus, controlling larvae is very im- portant. Therefore, the aim of research was to study the impact of B. thuringiensis-based bio-insecticide application