Which mosquito control method is least effective for reducing larval populations?

Daily monitoring is least effective for reducing larval populations because it is primarily a method used to gather data and assess mosquito presence rather than actively diminish the population. This approach allows for the detection of mosquito breeding sites and may inform future control measures, but it does not directly eliminate larvae or prevent their development.

In contrast, source reduction involves eliminating standing water where mosquitoes breed, insecticide applications target both larvae and adult mosquitoes to reduce populations effectively, and biological control introduces natural predators or pathogens that target mosquito larvae. While monitoring is crucial for understanding mosquito habits and planning control strategies, it does not produce immediate results in larval population reduction. Thus, it serves a supportive role rather than an active one in pest management.