Larvicidal Effect of Aluminium Sulphate Concentration Againts Culex Mosquito in Mashi Local Government Area, Katsina State

ABSTRACT
This study investigates the efficacy of aluminium sulphate as a larvicide against Culex mosquito larvae, providing strong evidence for its effectiveness in mosquito control. The experiment revealed a dose-dependent mortality rate, where higher concentrations of aluminium sulphate resulted in quicker and more significant larval mortality. Concentrations of 8% and 10% achieved over 90% mortality within the first 12 hours and 100% mortality within 48 hours, while lower concentrations of 2% and 4% also resulted in complete mortality, albeit over a longer period. These findings indicate the compound's potential for both immediate and sustained mosquito control. The results support the hypothesis that aluminium sulphate disrupts the larval environment, leading to mortality. Factors such as the ionic properties of aluminium and its effect on water turbidity likely contribute to its effectiveness. The study's findings highlight aluminium sulphate as a viable option for large-scale mosquito control programs, validating its potential for use in diverse operational settings. Further analysis of lethal concentrations (LC90 and LC95) confirmed the compound's potency. The LC90 value demonstrated that even low concentrations could achieve high mortality, which is advantageous in resource-limited areas where affordability is key. Additionally, the narrow gap between LC90 and LC95 values indicates that slight increases in dosage can significantly improve larvicidal efficacy, offering flexibility in application under different environmental conditions. The time-dependent mortality trends revealed aluminium sulphate’s rapid action in reducing mosquito populations. Mortality increased substantially within the first 24 hours, especially at higher concentrations, indicating that the compound disrupts the larval life cycle swiftly. By 48 hours, all concentrations achieved complete mortality, underscoring its sustained effectiveness. These findings emphasize the importance of exposure duration, showing that even economically conservative applications can be effective if enough time is allowed. Residual susceptibility and resistance analyses indicated that aluminium sulphate has minimal risk of developing resistance. At higher concentrations, susceptibility rates exceeded 90%, while resistance remained below 10%. This is a significant advantage over conventional chemical larvicides, which often face resistance issues. The compound’s minimal likelihood of resistance makes it a sustainable option for long-term mosquito control programs, particularly in areas where resistance to other larvicides is a concern. Behavioral observations further confirmed the mode of action of aluminium sulphate. Larvae exposed to the compound exhibited significant disruptions in motor functions and feeding activities. At lower concentrations, larvae displayed erratic swimming and reduced movement, while higher concentrations caused immediate immobilization and visible physical damage, such as body segment deformation. These behavioral changes, along with the mortality data, reinforce the compound’s efficacy in disrupting larval physiology. While the study demonstrated high larvicidal efficacy, environmental considerations were also taken into account. Aluminium sulphate’s performance in natural environments may be influenced by factors like organic matter content and water pH, which can affect its solubility and bioavailability. However, its biodegradability and low environmental persistence make it a safer alternative to synthetic chemical larvicides. These findings, consistent with previous studies, suggest that aluminium sulphate can be integrated into existing mosquito control programs, potentially in combination with other methods for enhanced effectiveness and sustainability.