WHO Cone Bioassay Test The WHO cone bioassays will be performed using the cone method (WHOPES 2005.11) on treated and non-treated bed-nets with wild caught (manually collected) sandflies at 1 month, 6 months and 12 months after intervention. Bioassays will be carried out at room temperature at 25o- 29oC and 75-85% humidity. Resting sandflies will be collected manually by aspirator during early morning and evening. In each net, 10-12 female sand flies will be introduced in each of the cones placed against the DWL / Wall for 30 minutes. The sand flies will be then transferred from each cone to a paper cup for observation. They will be observed over 24 hours to calculate the mortality. The mortality rates of sand flies will be corrected with Abbot's formula (WHOPES 2005.11).