COMPARATIVE ANALYSIS ON TWO CLASSES OF AEROSOLS IN THE CONTROL OF AEDES AEGYPTI AND CULEX PIPIENS MOSQUITO

Mosquitoes are two winged flies belonging to the order Diptera, and family Culicidae. They are important to public health because of their blood sucking and disease transmitting habit. Globally, vector control programs, use insecticides available as aerosol sprays, insecticide-treated nets (ITNs), to control mosquito populations. This study aimed to compare two classes of insecticides—Pyrethroids and organophosphates—formulated as aerosols on two mosquito genera: Aedes and Culex. The insecticide susceptibility (WHO standard) test was conducted on 2 to 5 days old, glucose-fed, non-blood fed mosquitoes. The mosquitoes were exposed to the insecticides in a controlled room, with knockdown and mortality recorded after 60 minutes and again after 24 hours. Three replicates of 20 mosquitoes were tested for each insecticide along with a control group bringing the total number of mosquitoes used to three hundred and sixty (360), and any control mortality over 20% was rejected, while mortality between 5% and 20% was corrected using Abbott’s formula. Results were analyzed using probit analysis to determine the knockdown times for 30% of the mosquitoes. The knockdown results for Aedes aegypti mosquitoes showed that Pyrethroid aerosols had the lowest KDT30 (time to knock down 30% of mosquitoes) at 7.94 minutes, while organophosphates exhibited a higher KDT30 of 15.85 minutes. In contrast, Culex pipiens showed a higher KDT30 of 15.85 minutes for Pyrethroids compared to a much lower KDT30of 1.99minutes for organophosphates. The 24-hour mortality assessment revealed resistance in both mosquito species to both insecticide classes. Aedes aegypti had a mortality rate of 96% for Pyrethroids and 89% for organophosphates, while Culex pipiens recorded mortality rates of 93% and 94% for Pyrethroids and organophosphates, respectively. The results showed a high recovery rate for the exposed mosquitoes given the high KDT30 values and low mortality which indicates resistance to insecticide according to WHO guidelines; where 98-100% mortality range indicates susceptible mosquito population, and 90-97% mortality suggest that the presence of resistant genes in the vector population must be confirmed. The widespread resistance observed in both species in this study, underscores the urgent need for innovative and integrated mosquito control approaches to effectively manage resistant populations.