A randomized test was conducted to verify the quality and efficacy of newly supplied ‘Malathion’ insecticide before field use for adult mosquito control by the Dhaka North City Corporation (DNCC).
The DNCC conducted this mosquito medicine testing activity on Wednesday (16 September) afternoon at the Gabtoli kitchen market premises in the capital. To ensure the quality of the new insecticide supplied by the contractor for adult mosquito control, the field test was held in the presence of officials from the Department of Agricultural Extension, IEDCR, and DNCC.
A completely randomized method was followed to maintain neutrality in the drum selection process. Attending officials threw pieces of brick aiming at the drums, and samples were collected for testing from whichever drums were hit. Subsequently, samples collected from three separate drums were loaded into fogging machines.
As part of the efficacy test, 50 Culex mosquitoes were placed in each of nine net cages (450 mosquitoes in total), and smoke was applied normally from a distance of four feet. During the ‘knockdown’ test conducted 20 minutes after applying the medicine, it was observed that all mosquitoes in eight cages were lying unconscious, while only two mosquitoes were flying in one cage. The mosquitoes used in this test were collected in their larval stage from outside the capital so that there was no risk of prior exposure to pesticides.
However, experts stated that the 20-minute knockdown test is not final. A 24-hour wait is required to confirm the actual mortality rate of the mosquitoes under the insecticide’s effect. For this purpose, the cages treated with the samples are being monitored after providing glucose-mixed food. Additionally, to compare the natural lifespan of mosquitoes in a normal environment, monitoring is also being conducted by placing mosquitoes in three separate untreated control cages, the final results of which will be known on Thursday afternoon.
Speaking about the overall testing process, DNCC Chief Health Officer Brigadier General Imrul Kayes Chowdhury said, “This test was conducted following World Health Organization standards. After the field-level testing, one sample will be sent to the IEDCR laboratory for a bio-efficacy test, and another sample will go to the Plant Protection Wing of the Department of Agricultural Extension to verify its chemical composition. Clearance for using the medicine will only be given after passing the three-tier testing process.”
DNCC Chief Store and Purchase Officer Md. Kamruzzaman informed that a work order was issued to the contractor to supply a total of 600,000 liters of Malathion. Under the first phase of the agreement, the DNCC has received 200,000 liters of medicine packed in 1,000 drums of 200-liter capacity each, the quality verification of which is currently underway.
