Resistance to Temephos of Aedes aegypti Linnaeus Larvae (Diptera: Culicidae) - ความต้านของลูกน้ำยุงลาย Aedes aegypti Linnaeus (Diptera: Culicidae) ต่อสารที่มีฟอส

Abstract

        This study was conducted to measure the resistance to temephos of Aedes aegypti Linnaeus larvae in the northeast of Thailand. Ae. aegypti larvae were collected from urban of 7 provinces in the northeast of Thailand namely Ubon Ratchathani, Si Sa Ket, Yasothon, Amnat Charoen, Mukdahan, Nakhon Panom, Kalasin and Sakon Nakhon provinces during April-June 2006. The fourth larval stage were tested in 0.02 mg/l temephos solution as recommended by the World Health Organization as a standard method. The results demonstrated that Ubon Ratchathani, Si Sa Ket, Yasothon, Amnat Charoen, and Kalasin Ae. aegypti strains had mortality indicating susceptibility. When the fourth larval stage, were selected for bioassay test, the LC50 and LC95 of Mukdahan Ae. Aegypti larvae strains were the highest, with values of 0.01154 and 0.0296 mg/l respectively. However, when compared with the WHO standard susceptible strain, the resistance of the Mukdahan strain were 12.68 and 11.93 fold for the LC50 and LC95 respectively. The conclusion of this study is that Mukdahan Ae. aegypti larvae strain can develop higher levels of resistance to temephos than other strains. The results obtained from this research study can be applied to other regions with the same problem with control of Ae. aegypti larvae as an important part of a Dengue Hemorrhagic Fever control program.

Key words: resistance, temephos, Aedes aegypti