Bacillus thuringiensis subsp. Kurstaki strain PB 54

Bacillus thuringiensis subsp. kurstaki (Btk) is a soil-dwelling bacterium that serves as a highly effective biological insecticide. Its primary mode of action is based on the production of crystalline delta-endotoxin proteins during the bacterial sporulation process.

When target pests ingest treated foliage, the alkaline environment of the insect's midgut solubilizes the crystalline proteins, releasing active toxins that cause severe damage to the gut lining.

The damage to the epithelial cells leads to a cessation of feeding, which typically occurs within hours of ingestion, effectively preventing further damage to the crop.

Following the disruption of the digestive tract, the insect suffers from paralysis and secondary infections caused by the entry of bacteria into the body cavity, leading to death within a few days.

Btk is highly specific to lepidopteran larvae, ensuring that beneficial insects, such as pollinators and natural predators, remain unharmed during application.

This biological agent is specifically designed to manage a broad spectrum of pests from the order Lepidoptera, focusing on the larval stages when they are most active.

Key targets include common vegetable pests such as cabbage loopers, cabbage worms, and various species of diamondback moths that cause significant yield loss.

In fruit production and viticulture, it is widely used to suppress populations of leafrollers, fruit worms, and various other moth species that attack ripening fruit.

Integrated Pest Management (IPM) programs prioritize Btk for its environmental safety and ability to provide control without disrupting beneficial insect populations.

• Cabbage loopers
• Diamondback moths
• Leafrollers
• Fruit worms
• Armyworms

Application rates are determined by the specific formulation of the product, crop type, and the severity of the pest infestation observed in the field.

The timing of application is critical; it is most effective when applied at the earliest signs of egg hatch, targeting young larvae before they cause extensive damage.

Thorough coverage of the foliage is essential because the insecticide must be ingested by the larvae to be effective, necessitating the use of appropriate spraying equipment.

Repeating applications every 7 to 10 days is recommended during peak periods of pest activity to provide continued protection as new larvae hatch.

Environmental conditions during application should ideally be mild, as extreme heat or intense sunlight can affect the longevity and efficacy of the biological material on the leaf surface.

The main limitation of Btk products is their susceptibility to ultraviolet (UV) radiation, which can rapidly degrade the active toxin proteins upon exposure to direct sunlight.

To maximize efficacy, it is highly recommended to perform spraying operations during the early morning or late evening to minimize UV degradation.

Because Btk lacks systemic activity, poor spray coverage on either side of the leaves can result in surviving larvae, necessitating precise and uniform application.

Avoid mixing Btk with broad-spectrum fungicides or alkaline substances in the spray tank, as these may interfere with the viability of the bacterial spores.

Long-term storage of the product should be in a cool, shaded environment to ensure that the bacterial spores retain their viability and potency over time.