Bacterial Larvicide,Bacillus thuringiensis israelensis Strain AM 65-52 Water Dispersible Granule Formulation Impacts Both Dengue Vector,Aedes aegypti (L.) Population Density and Disease Transmission in Cambodia

A multi-phased study was conducted in cambodia from 2005–2011 to measure the impact of larviciding with the bacterial larvicide,bacillus thuringiensis israelensis (bti),a water dispersible granule (wg) formulation on the vector,aedes aegypti (l.) and the epidemiology. in our studies,all in-use containers were treated at 8 g/1000 l,including smaller containers and animal feeders which were found to contribute 23% of ae aegypti pupae. the treated waters were subjected to routine water exchange activities. pupal production was suppressed by an average 91% for 8 weeks. pupal numbers continued to remain significantly lower than the untreated commune (utc) for 13 weeks post treatment in the peak dengue vector season (p<0.05). suppression of pupal production was supported by very low adult numbers in the treated commune. an average 70% of the household harbored 0–5 ae aegypti mosquitoes per home for 8 weeks post treatment,but in the same period of time >50% of the household in the utc harbored ≥11 mosquitoes per home. the adult population continued to remain at significantly much lower numbers in the bti treated commune than in the utc for 10–12 weeks post treatment (p<0.05). in 2011,a pilot operational program was evaluated in kandal province,a temephos resistant site. it was concluded that 2 cycles of bti treatment in the 6 months monsoon season with complete coverage of the target districts achieved an overall dengue case reduction of 48% in the 6 treated districts compared to the previous year,2010. five untreated districts in the same province had an overwhelming increase of 352% of dengue cases during the same period of time. the larvicide efficacy,treatment of all in-use containers at the start of the monsoon season,together with treatment coverage of entire districts interrupted disease transmission in the temephos resistant province. © 2016 setha et al.