AGRIVITA Journal of Agricultural Science. 2022. 44(3): 419-430 AGRIVITA Journal of Agricultural Science www.agrivita.ub.ac.id 419 INTRODUCTION Spodoptera litura (F.) is harmful for plant and can cause economic loss for farmers. According to Tengkano & Suharsono (2005), the agriculture crops located at 22 provinces in Indonesia, like west java, east java, south Sumatra etc., were attacked by S. litura with an area of 11,163 ha/year. This research was carried out at Garut and West Bandung districts, well known as the production centres of vegetables in West Java (BPS, 2016). Control of armyworm on farm level are generally still using synthetic insecticides (Laoh, Puspita, & Hendra, 2003; Razak, Santhakumar, Mageswari, & Santhi, 2014) which is in long intensive use, it may trigger the occurance of S. litura resistance in both regions. ARTICLE INFO Keywords: Acetylcholinesterase Armyworm Botanical insecticide Esterase Glutathione s-transferase Article History: Received: March 14, 2022 Accepted: August 25, 2022 * ) Corresponding author: E-mail: danar.dono@unpad.ac.id ABSTRACT This study aimed to obtain resistance information of S. litura from Karangpawitan and Lembang districts (West Java, Indonesia) against chlorpyrifos insecticides (200 g/l) and their sensitivity to oil mixture of A. indica and C. nardus (1:1) using feeding and topical assay. The activity of acetylcholinesterase, esterase, and glutathione s-transferase from S. litura larvae in both populations were tested to determine their role in insect resistance. Results showed that S. litura population from Lembang had a higher level of resistance to chlorpyrifos compared to Karangpawitan. The sensitivity of the two S. litura populations had a relatively similar resistance ratio (RR) value of less than 1 to botanical insecticide. These indicated that resistant population could be controlled by a mixture of this botanicals insecticide. Enzyme activity test indicated that chlorpyrifos at a concentration of 0.26% could inhibit the acetylcholinesterase activity of insect population from Karangpawitan by 98.66% while those from Lembang, it was only 35.31%. Specifc activity of esterase from Karangpawitan was 13.37 units/mg while Lembang population was 119.65 units/ mg. The specifc activity of the Glutathione S-Transferase (GST) of Karangpawitan population was 1140.82 units/mg while Lembang population was 793.73 units/mg. The high activity of the three enzymes could be responsible for resistance of S. litura larvae to chlorpyrifos. ISSN: 0126-0537 Accredited First Grade by Ministry of Research, Technology and Higher Education of The Republic of Indonesia, Decree No: 30/E/KPT/2018 Cite this as: Ramadhan, R. A. M., Widayani, N. S., Dono, D., Hidayat, Y., & Ishmayana, S. (2022). Resistance level and enzyme activity of Spodoptera litura F. to chlorpyrifos and their sensitivity to the oil formulation of Azadirachta indica Juss. and Cymbopogon nardus (L.) Rendl.. AGRIVITA Journal of Agricultural Science, 44(3), 419-430. http://doi. org/10.17503/agrivita.v41i0.3729 Resistance Level and Enzyme Activity of Spodoptera litura F. to Chlorpyrifos and Their Sensitivity to the Oil Formulation of Azadirachta indica Juss. and Cymbopogon nardus (L.) Rendl. R. Arif Malik Ramadhan 1,2) , Neneng Sri Widayani 2) , Danar Dono 3*) , Yusup Hidayat 3) and Safri Ishmayana 4) 1) Agrotechnology Study Program, Universitas Perjuangan, Tasikmalaya, West Java, Indonesia 2) Agronomy Study Program, Faculty of Agriculture, Universitas Padjadjaran, Bandung, West Java, Indonesia 3) Department of Plant Pests and Diseases, Faculty of Agriculture, Universitas Padjadjaran, Bandung, West Java, Indonesia 4) Department of Chemistry, Faculty of Mathematics and Natural Sciences, Universitas Padjadjaran, Bandung, West Java, Indonesia