BIODIVERSITAS ISSN: 1412-033X Volume 19, Number 1, January 2018 E-ISSN: 2085-4722 Pages: 31-36 DOI: 10.13057/biodiv/d190105 Detection of Ace-1 gene with insecticides resistance in Aedes aegypti populations from DHF-endemic areas in Padang, Indonesia HASMIWATI ♥ , SELFI RENITA RUSJDI, EKA NOFITA Department of Parasitology, Faculty of Medicine, Universitas Andalas. Jl. Perintis Kemerdekaan, Jati Baru, Padang Timur, Padang 25129, West Sumatra, Indonesia. Tel./fax.: +62-751-30706, ♥ email: hasmiwati65@gmail.com Manuscript received: 7 August 2017. Revision accepted: 17 November 2017. Abstract. Hasmiwati, Rusjdi SR, Nofita E. 2018. Detection of Ace-1 gene with insecticides resistance in Aedes aegypti populations from DHF-endemic areas in Padang, Indonesia. Biodiversitas 19: 31-36. Aedes aegypti is distributed widely in West Sumatra as a primary vector of Dengue hemorrhagic fever, especially in Padang City. Synthetic insecticide control is one currently used method to prevent mosquito-borne diseases. The extensive, long-term application of Temephos along with inappropriate dosages, have resulted in the development of resistance in Ae. aegypti populations. Mutation of the Ace-1 gene, encoding an acetyl cholinesterase, is one of the mechanisms that confer resistance to organophosphate (OP). The Temephos resistance status of Ae. aegypti in Padang city has not yet been studied. This study aimed to investigate the resistance status of Ae. aegypti and identify any possible mutation (s) of the Ace-1 gene in Padang city. Ae. aegypti samples were collected in five population in Padang city (Jati (JT), Gunung Pangilun (GP), Lubuk Minturun (LM), Korong Gadang (KG), and Bandar Buat (BB)). The larval susceptibility to Temephos was tested by larval bioassays with Temephos pestanal at 0.02 mg/L dosages. Larval susceptibility was determined by mortality percentage values. The relationship between Ace-1 genotypes and the resistant phenotype was analyzed by percentage of genotype frequency. Out of five populations, assessed by larval bioassays, JT and GP were resistant to Temephos; LM, KG, and BB were tolerant. A total of 50 individuals from larval bioassays were genotyped for Ace-1 gene. Our findings showed that Ace-1 was 495 bp in length. Mutation was not found in the G119S location but in the T506T location. Three alleles in T506T location were detected, including a wild type allele, TT (65.21%), and two mutant alleles, TA (26.08%), AA (8.69%). The use of Temephos showed that some Ae. aegypti populations were resistant, others were tolerant, but no population was vulnerable to Temephos. A novel mutation was detected as substitution in T506T location (ACT>ACA). Keywords: Aedes aegypti, insecticide resistance, Ace-1gene, susceptibility test Abbreviations: DHF: Dengue Hemorrhagic Fever, Ace-1: Acetyl cholinesterase-1, OP: Organophospate INTRODUCTION Prevention and control of Dengue Hemorrhagic Fever (DHF) depends on controlling the mosquito vector, Aedes aegypti. Since the Second World War, chemical insecticides have been used widely for controlling vector populations and reducing disease transmission, but their efficacy is now threatened by resistance mechanisms developed by mosquitoes. Resistance to insecticides by Ae. aegypti is extensive including most of the currently utilized vector control insecticides (Ranson et al. 2010). The extensive and long-term application of OP (Organophosphate) at inappropriate dosages (1x3 months OP is applied, but furthermore application do not follow the instructions), has resulted in increasing levels of resistance in Ae. aegypti populations. Resistance to OP specifically has been linked to mutations in the Ace gene, where mutations at specific sites have resulted in decreased sensitivity to insecticides (Poupardin et al. 2014). Organophosphate is one insecticide commonly used to control Ae. aegypti, Temephos or abate are OP used against larvae, and Malathion for adult mosquitoes. Temephos has been utilized worldwide about for 40 years, and resistance to Temephos has been reported in many countries, including Thailand (Saelim et al. 2005), Mexico (Deming et al. 2016), Brazil (Lima et al. 2003), Peru (Rodriguez et al. 2007), Columbia (Ronald MS ), El Salvador (Lazcano et al. 2009), Argentina (Llinas et al. 2010), Bolivia (Biber et al. 2010), Venezuela (Rodriguez et al. 2001), Malaysia (Dhang et al. 2008), India (Singh et al. 2014), and Indonesia (Mulyatno et al. 2012). Previous studies have demonstrated resistance to Temephos by Ae. aegypti, but the underlying molecular mechanisms of this resistance remain unclear. Hence, monitoring of Ae. aegypti resistance is very important to successfully control Ae. aegypti populations. The molecular characterization of Ae. aegypti underlying resistance mechanism to OP is crucial for tracking down resistance alleles and improving management strategies to OP resistance (Corbel et al. 2013). More than 760 candidate genes were captured and deep sequenced in several populations of the dengue mosquito Ae. aegypti displaying distinct genetic backgrounds and various resistance levels to the insecticide (Faucon et al. 2015). Resistance to OP is determined to two mechanisms, the first is an increase in detoxification enzymes (such as, acetylcholinesterase, glutationtransferase, esterase), and secondly, mutation of Ace-1 gene encoding acetyl-