Study on efficacy of expired Temephose against Aedes aegypti Larva

Abstract

This experiment was carried out in March 2006 in the Laboratory of the Office of Vector Borne Disease Control Center in Chiang Rai (VBDC)/ The experiment aimed to determine the efficacy of expired Temephose against Aedes aegypti larva. Young Aedes larvae were collected from Ban Pa Yan Mon, Rob Wieng canton, Muang District, Chiangm Rai province. After identification, 200 of healthy 3-4th instar larva were used in the experiment. In addition expired 1 and 2% Temephose were obtained from VBDC and the Chiang Rai Provincial Health Office. 1ppm solution of expired Temephose were prepared by 1 and 0.5 gm per 10 liter of eater for 1% and 2% SG Tepephose. Tap water without any Temephose SG was used as a control. To each concentration, 50 aedes larva were added. Every 30 minutes the number of larva deaths were observed and counted, then the mortality rate (%) was calculated. All experiments lasted 180 minutes. The results showed that the mortality rate after 60 minutes exposed were 16%(8/50), 26%(13/50) and 10%(5/50) for 1%SG Temephose from Chiang Rai Provincial Health Office and 1% and 2% SG Temphose from VBDC respectively. The mortality rate was increased to 50% when exposed for 90 minutes. Furthermore a 100% mortality rate of Aedes aegypti larva were observed after 150 minutes exposed in 1% SG collected from VBDC and Chiang Rai Provincial Health Office, whereas it was observed at 180 minutes for the 2% SG Temephose collected from VBDC.