Transgenic Drosophila to Functionally Validate Fall Armyworm ABCC2 Mutations Conferring Bt Resistance

Area of Science:

• Entomology
• Molecular Biology
• Pest Management

Background:

• The fall armyworm (FAW) is a major invasive agricultural pest causing significant crop losses globally.
• Current control methods, including chemical insecticides and Bacillus thuringiensis (Bt) toxins, face challenges due to pest resistance.
• The ABCC2 transporter is implicated in Bt toxin action, and mutations in its SfABCC2 gene are linked to FAW resistance.

Purpose of the Study:

• To investigate the role of the SfABCC2 gene in Bt toxin susceptibility and resistance in the fall armyworm.
• To validate the function of specific SfABCC2 mutations associated with Bt resistance using a heterologous expression system.
• To assess the potential for cross-resistance between different Bt toxins targeting the ABCC2 transporter.

Main Methods:

• Expression of the wildtype and mutated SfABCC2 gene in Drosophila melanogaster.
• Tissue-specific expression of SfABCC2 to confer Bt toxin susceptibility in Drosophila.
• Functional validation of FAW ABCC2 mutations through toxicity bioassays using a Bt-based insecticide (Xentari).

Main Results:

• Ectopic expression of wildtype SfABCC2 in Drosophila rendered the flies susceptible to Bt toxins.
• Introduced mutations in the extracellular loop 4 (ECL4) of SfABCC2 conferred resistance to Bt toxins.
• Transgenic Drosophila models effectively validated the role of specific SfABCC2 mutations in FAW Bt resistance.

Conclusions:

• Transgenic Drosophila serves as a robust model for studying Bt resistance mechanisms in the fall armyworm.
• Mutations in the SfABCC2 gene, particularly in ECL4, are key drivers of Bt resistance in FAW.
• This research provides insights into potential cross-resistance issues, aiding in the development of sustainable pest management strategies.