Transgenic crops expressing Bacillus thuringiensis toxins and biological control

Area of Science:

• Agricultural Entomology
• Environmental Toxicology
• Biotechnology

Background:

• Transgenic crops producing Bacillus thuringiensis (Bt) insecticidal proteins are increasingly adopted globally.
• Concerns exist regarding the impact of Bt crops on non-target organisms, particularly biological control agents.
• Regulatory assessment of Bt crop effects necessitates a tiered, step-wise approach.

Purpose of the Study:

• To evaluate the impact of Bt crops on non-target biological control organisms.
• To compare the effects of Bt crops with conventional insecticide applications on natural enemies.
• To assess the compatibility of Bt crops with integrated pest management (IPM) strategies.

Main Methods:

• Laboratory and glasshouse studies using Bt-susceptible herbivores as prey/hosts for natural enemies.
• Field studies monitoring the abundance and activity of parasitoids and predators in Bt and non-Bt crop environments.
• Comparative analysis of impacts from Bt crops versus conventional insecticides on biological control agents.

Main Results:

• Laboratory studies indicated effects on natural enemies only when using sublethally damaged, Bt-susceptible herbivores, with no direct toxicity observed.
• Field studies demonstrated comparable abundance and activity of parasitoids and predators in both Bt and non-Bt crop systems.
• Conventional insecticide applications typically exhibited negative effects on biological control organisms, unlike Bt crops.

Conclusions:

• Bt crops generally pose minimal risk to non-target biological control organisms.
• Bt crop adoption can lead to reduced reliance on conventional insecticides, benefiting IPM.
• Bt-transgenic varieties can be a valuable component of sustainable agriculture and integrated pest management systems.