Which statement correctly describes the timing and form for applying Bti to control larvae?

Which statement correctly describes the timing and form for applying Bti to control larvae?

• A. Applied as a liquid poured into moving water.
• B. Sprayed as a fog over land
• C. Applied as a powder on the water surface
• D. Injected into the water at depth

Answer: (A)

Bti works by producing toxins in the gut of aquatic larvae after they ingest the bacteria, so it must be applied directly to the water where larvae are developing and feeding. The timing should coincide with the presence of larvae, i.e., during their active feeding stages, so the larvae actually ingest the Bti. The form matters because you want the product to reach the larvae in the water column. A liquid formulation poured into moving water spreads with the current, distributing the active material throughout the habitat where larvae reside and increasing the chance that feeding larvae ingest it. Other approaches don’t deliver the product to the larval habitat effectively: spraying a fog over land misses aquatic sites; applying a powder on the water surface is less reliable for distribution and may wash away or settle quickly; injecting into the water at depth places it away from where most larvae feed. So, applying a liquid formulation into moving water, timed to when larvae are present, is the best way to ensure Bti reaches and is ingested by the larvae.

Bti works by producing toxins in the gut of aquatic larvae after they ingest the bacteria, so it must be applied directly to the water where larvae are developing and feeding. The timing should coincide with the presence of larvae, i.e., during their active feeding stages, so the larvae actually ingest the Bti.

The form matters because you want the product to reach the larvae in the water column. A liquid formulation poured into moving water spreads with the current, distributing the active material throughout the habitat where larvae reside and increasing the chance that feeding larvae ingest it. Other approaches don’t deliver the product to the larval habitat effectively: spraying a fog over land misses aquatic sites; applying a powder on the water surface is less reliable for distribution and may wash away or settle quickly; injecting into the water at depth places it away from where most larvae feed.

So, applying a liquid formulation into moving water, timed to when larvae are present, is the best way to ensure Bti reaches and is ingested by the larvae.