Figure 2.

Original World Health Organization (WHO) tube method as outlined in the “8th Report of the Expert Committee on Insecticides” [24], reproduced with permission of Rajpal Singh Yadav, WHO. (A) Collect test mosquitoes using a mouth aspirator. (B) Mosquitoes should be collected in batches of no more than 10. (C) Test mosquitoes are gently transferred to the holding-tubes until they number 20–25 per tube. (D) The exposure tube is attached, and the slide is opened. Mosquitoes are then gently blown from the holding-tube to the exposure tube. The holding-tube is detached and set aside (E) The exposure tubes are left standing upright for 1 h during the exposure. (F) Mosquitoes are transferred back to the holding-tube by reversing the process described in C. The holding-tube is set upright, and a pad of wet cotton wool is placed on top. Tubes are held for 24 h, at which point mortality counts are made.