What has been known to help counter resistance in mosquito treatment?

• A. Using higher chemical concentrations alone.
• B. Combining Bti & Bsph.
• C. Using a single product repeatedly.
• D. Ignoring resistance issues.

Answer: (B)

Combining two larvicides with different modes of action helps counter resistance because it makes it much harder for mosquito populations to adapt. Bti and Bsph are bacterial products that kill larvae through distinct toxins, so using them together broadens the attack and reduces the chance that a population has or develops resistance to both. This approach spreads selection pressure across different mechanisms, slowing or preventing resistance from taking hold. Relying on higher chemical concentrations alone can increase environmental harm and quickly selects for resistant individuals, using a single product repeatedly pushes resistance forward, and ignoring resistance issues leaves the problem unaddressed. So, using both Bti and Bsph together is a known, effective strategy to manage resistance in mosquito control.