en بیوشیمی Biochemistry مقالات اصلی Original Article <div style="text-align: justify;"><em><strong>Background:</strong></em> Dengue hemorrhagic fever (DHF) is a significant health problem. The high number of cases&nbsp;requires preventions, including controlling the dengue vector, Aedes aegypti mosquito. One of the control&nbsp;methods is the use of insecticides containing organophosphate. This study aims to detect organophosphate&nbsp;resistance in Aedes aegypti from DHF endemic subdistrict, Riau, Indonesia by a sensitivity test of&nbsp;temephos and 5% malathion and measuring the activity of non-specific alpha and beta esterase enzymes.<br> <br> <strong><em>Methods: </em></strong>This observational study determined Aedes aegypti resistance from larvae to adult in one DHF&nbsp;endemic subdistrict in Riau, Indonesia. The bioassay was used for temephos sensitivity of Aedes aegypti&nbsp;larvae. The LC99 value was analyzed using probit and compared with the diagnostic value from WHO.&nbsp;The WHO susceptibility test was conducted to determine 5% malathion resistance from adult mosquitoes.&nbsp;The mortality of less than 90% was declared as resistant. Measurement of alpha and beta esterase levels&nbsp;used Lee&#39;s microplate assay technique based on visual identification and absorbance value (AV).<br> <br> <em><strong>Results:</strong></em> The results showed that Aedes aegypti were resistant to temephos. It also showed that adult&nbsp;mosquitoes were resistant to 5% malathion. Based on the alpha esterase activity test, it was found that&nbsp;most of the mosquitoes showed very sensitive meanwhile, based on the beta esterase activity test, most of&nbsp;the mosquitoes were moderate resistance.<br> <br> <strong><em>Conclusions:</em></strong> This study suggests that Aedes aegypti population from DHF endemic subdistrict in Riau,&nbsp;Indonesia are indicated to develop resistance to organophosphate.</div> Aedes aegypti, Dengue Hemorrhagic fever, Organophosphate, Resistance. 589 596 http://rbmb.net/browse.php?a_code=A-10-709-1&slc_lang=en&sid=1 Suri Dwi Lesmana suri.dwi@lecturer.unri.ac.id 100319475328460012430 100319475328460012430 Yes Department of Parasitology, Faculty of Medicine, Universitas Riau, Pekanbaru, Indonesia. Esy Maryanti 100319475328460012431 100319475328460012431 No Department of Parasitology, Faculty of Medicine, Universitas Riau, Pekanbaru, Indonesia. Elva Susanty 100319475328460012432 100319475328460012432 No Department of Parasitology, Faculty of Medicine, Universitas Riau, Pekanbaru, Indonesia. Dedi Afandi 100319475328460012433 100319475328460012433 No Department of Forensic and Medicolegal, Faculty of Medicine, Universitas Riau, Pekanbaru, Indonesia. Wida Harmas 100319475328460012434 100319475328460012434 No Faculty of Medicine, Universitas Riau, Pekanbaru, Indonesia. Delly Noer Octaviani 100319475328460012435 100319475328460012435 No Faculty of Medicine, Universitas Riau, Pekanbaru, Indonesia. Iskandar Zulkarnain 100319475328460012436 100319475328460012436 No Faculty of Medicine, Universitas Riau, Pekanbaru, Indonesia. Muhammad Agung Bariq Pratama 100319475328460012437 100319475328460012437 No Faculty of Medicine, Universitas Riau, Pekanbaru, Indonesia. Mislindawati Mislindawati 100319475328460012438 100319475328460012438 No Department of Parasitology, Faculty of Medicine, Universitas Riau, Pekanbaru, Indonesia.