The mosquitoes are nuisance pests to humans and represent a global health challenge. The larvicidal activities of Commiphora molmol resin, mirazid, and formulated and crystalline acetylsalicylic acid (F-ASA and C-ASA, respectively) were evaluated against the 2nd and 4th instar larvae of Culex pipiens at 27°C, after 48 hours post-treatment in different water qualities. Water samples were collected from the tap, canal, and pool. The water pH, nitrate, salinity, and dissolved oxygen were measured. The results showed that the larvicidal activity of the tested compounds was increased by increasing their concentrations. The mortality reached 100% and 98.4% for the 2nd instar larvae at 160 ppm, 100% and 90.4% for the 4th instar larvae at 320 ppm of mirazid and C. molmol, respectively. The mortality induced by F-ASA and C-ASA reached 99.2% and 75.2% for the 2nd instar larvae at 1200 ppm, 100% and 92.0% for the 4th instar larvae at 2000 ppm, respectively. The efficiency of the tested materials against the 4th instar larvae was affected by the water quality; whereas their LC50 values were 38.3-1045.9 ppm in tap water; while at canal and pool water the LC50 values were 44.5-1073 and 49.8-1126.0 ppm, respectively, at 27°C and 48 hours post-treatment. The correlation coefficient between the susceptibility of Cx. pipiens larvae to the tested compounds and each physicochemical factor showed a positive correlation with water nitrate and dissolved oxygen. In conclusion, mirazid, C. molmol, F-ASA, and C-ASA can be good alternative agents for controlling mosquitos’ larvae in different water qualities. |
