Which mosquito life stage does Bti specifically target?

Bti, or Bacillus thuringiensis israelensis, is a naturally occurring bacterium that is specifically effective against the larval stage of mosquitoes. When ingested by mosquito larvae, Bti produces toxins that disrupt the larvae's digestive system, leading to their death. This specificity makes Bti particularly valuable in mosquito control programs, as it targets only the larval stage without affecting other life stages or non-target organisms, such as beneficial insects or aquatic animals.

In contrast, other life stages of mosquitoes—eggs, pupae, and adults—are not directly affected by Bti treatment. Eggs are laid in water but resist treatment as they are not actively feeding, and pupae are a non-feeding life stage floating just below the water's surface. Adult mosquitoes are fully developed and have moved out of the water, which further prevents any efficacy of Bti. Thus, the focus on the larval stage highlights the importance of targeted interventions in mosquito management, emphasizing the role that larvicides like Bti play in disrupting the mosquito life cycle effectively.